How large was the Pararhabdodon?
Pararhabdodon
"Pararhabdodon" most likely was a bipedal-quadrupedal herbivore, in the neighborhood of 6 m (19.7 ft) long, fully grown. The dorsal and sacral neural spines were elongate, so the animal would have had a tall back, like other hadrosaurids. Because the material is sparse, more specific conclusions cannot be reached.
Mastodon
Modern reconstructions based on partial and skeletal remains reveal that mastodons were very similar in appearance to elephants and, to a lesser degree, mammoths, though not closely related to either one. Compared to mammoths, mastodons had shorter legs, a longer body and were more heavily muscled, a build similar to that of the current Asian elephants. The average body size of the species "M. americanum" was around in height at the shoulders, corresponding to a large female or a small male; large males were up to in height. Among the largest male specimens, the 35-year-old AMNH 9950 was tall and weighed , while another was tall and weighed .
Brasilodon
Brasilodon ("Brazil tooth") is an extinct genus of cynodonts that lived during the Norian age of the Late Triassic Period, about 228 to 208.5 million years ago. The average length of "Brasilodon" is approximately 12 cm and weighed about 20 grams.The average size of this cynodont species is about the size of extant mice. Brasilodontids are most likely insectivores due to their teeth. The two species in this genus are "B. tetragonus and B. quadrangularis," two very small cynodonts belonging to the family Brasilodontidae.
Hypsilophodon
The first remains of "Hypsilophodon" were found in 1849; the type species, "Hypsilophodon foxii", was named in 1869. Abundant fossil discoveries were made on the Isle of Wight, giving a good impression of the build of the species. It was a small bipedal animal with an herbivorous or possibly omnivorous diet. "Hypsilophodon" reached up to in length, weighed about 20 kg (45 lbs), and was an agile runner. It had a pointed head equipped with a sharp beak used to bite off plant material, much like modern day parrots.
Dinosaur Walk Museum
Parasaurolophus: The Parasaurolophus, like the T-Rex, lived during the Cretaceous Period 76-66 million years ago. It grew to be long, high, and weighed almost 7,700 pounds. The Parasauolophus was an herbivore. The large crest was thought to be used for communication amongst males and females.
Pararhabdodon
Near the village Abella de la Conca, in the 1990s, palaeontologist Marc Boada discovered a new site in the Tremp Formation, bearing dinosaur fossils. From this site, later named Les Llaus (LL), a right dentary, specimen designation IPS SRA 27, was excavated. In 1997, Casanovas-Cladellas and colleagues stated this dentary was discovered from SRA, the site where the original "Pararhabdodon" remains were found. The following year, they described the specimen and referred it to "P. isonensis", and again stated it was from the same stratigraphic level. In 2006, the stratigraphy of the region was re-evaluated, and the dentary's location was corrected to the LL locality, away from and below the SRA locality.
Elaltitan
The holotype of "Elaltitan" was originally attributed to "Antarctosaurus sp." by Bonaparte & Gasparini (1979), and later tentatively referred to "Argyrosaurus" by Jaime Powell (1986, 2003). Philip D. Mannion and Alejandro Otero (2012), who named the genus, diagnosed "Elaltitan" by a unique combination of characters, as well as one autapomorphy. The autapomorphy (unique trait) is the presence of dorsoventrally tall neural arch restricted to anterior half of centrum (excluding condylar ball) in anterior-most caudal vertebrae. Other unusual characters include a spinopostzygapophyseal laminae in middle–posterior dorsal vertebrae bifurcate into medial and lateral branches, an astragalar ascending process that does not extend to the posterior margin of the astragalus and the presence of a calcaneum. Other potentially unusual features were also listed. These traits distinguish "Elaltitan" from all other titanosauriforms, including "Antarctosaurus" and "Argyrosaurus", as well as other sauropods from the lower member of the Bajo Barreal Formation, such as "Drusilasaura" and "Epachthosaurus". Based on comparisons with the morphologically similar femur of "Antarctosaurus"" giganteus", which was measured as in length, the complete femur of "Elaltitan" would be approximately the same size. This makes it one of the largest known sauropods ever to have existed. Mannion & Otero (2012) also pointed out that there are currently 39 Cretaceous South American titanosauriform genera considered to be valid, the majority of which (31) are from Argentina. Its weight has been estimated at in 2014, and at in 2018.
1946 Walraven
According to the survey carried out by NASA's Wide-field Infrared Survey Explorer with its subsequent NEOWISE mission, "Walraven" measures 9.2 kilometers in diameter and its surface has an albedo of 0.362, while the "Collaborative Asteroid Lightcurve Link" assumes a standard albedo for stony asteroids of 0.20, and calculates a diameter of 11.8 kilometers with an absolute magnitude of 12.0.
Paradoxides
The exoskeleton of "Paradoxides" is large to very large, relatively flat, oval to inverted egg-shaped, and about one and a half times longer than wide, with the greatest width across the genal spines. The headshield (or cephalon) is close to semicircular with long spines developing from the corners of the cephalon. As usual in trilobites, the dorsal suture runs along the top of the eye. As in all Redlichiina, this suture runs from the back of the eye slightly outward to the rear margin of the cephalon (a state called opisthoparian) opposite the base of the pleural spines. From the front of the eye the suture describes a slight S-curve forward cutting the front margin in front of the eye. The central raised area of the cephalon (or glabella) is divided in the occipital ring furthest to the back, followed by the first lobe that is, like the occipital ring, defined by a furrow across the midline and two more lobes that have furrows that do not connect across the midline. The frontal lobe is the widest and shaped like a segment of a circular band. It almost reaches the frontal edge of the cephalon. The eyelobe is short, opposite the first to third glabelar lobes. "Paradoxides" has a palate (or hypostome) with its front aligned with the front of the glabella and connected to the doublure (a condition science calls conterminant). Exceptionally, the hypostome is even fused with the frontal part of the doublure (called rostral plate), a character that distinguishes it from all other trilobites, except some Cambrian Corynexochida such as "Oryctocephalus", and "Fieldaspis".
Paratomarctus
"Paratomarctus" was one of the last of the Borophaginae and shared its North American habitat with other canidae: "Borophagus" (23.3—3.6 Mya), "Epicyon" (20.6—5.330 Ma), "Carpocyon" (20.4—3.9 Ma), Aelurodon (23.03—4.9 Ma), and the first emerging wolf, "Canis lepophagus" appearing 10.3 Ma.
Paramysis
There are 23 species classified into 8 subgenera. Body length ranges from . The largest species, like "P. eurylepis", "P. inflata", are found only in the Caspian Sea. Generic characters: subrostral plate; large eyes on short stalk; antennal scale with smooth outer margin, ended by strong spine, and distal segment rudimentary with five setae; four segments of pereiopod 1–4 carpopropodus; five segments in pleopod 4 of male. Consumed by fishes; particularly important for juvenile sturgeons and zander.
Procoptodon
"Procoptodon goliah" were unable to hop as a mode of transportation, and would have been unable to accelerate sufficiently due to their mass. Broad hips and ankle joints adapted to resist torsion or twisting, point to an upright posture where weight is supported by one leg at a time. Their broad hips also allowed for another important modification: large buttocks - a feature shared with other walking species. However, there is some ambiguity surrounding the possible locomotion of the "P. goliah". Some research suggests that this species was perhaps the largest hopping mammal to have ever existed. Research suggests that the most optimal weight for a large hopping marsupial is approximately 50–60 kg. Larger animals, especially the massive "P. goliah", would be substantially more at risk of tendon breakage while hopping. If "P. goliah" were to have travelled by hopping, the highest possible balance between size and speed would have been peaked because their bodies would surely have been the largest possible to be carried by this method of locomotion A more likely suggestion, based on the apparent anatomy allowed by the bone structure of "P. goliah", is that unlike modern kangaroos, which are plantigrade hoppers at high speeds and use their tails in pentapedal locomotion at slower speeds, "Procoptodon" was an unguligrade biped, walking in a fashion similar to hominids. Locomotion mechanics and physiology have been investigated through the examination of muscleoskeleton scaling patterns. The largest, "P. goliah", was tall and weighed up to . For "Procoptodon goliah", tendon stress was identified, which indicates limited locomotor capabilities, exposing a correlation between body mass and locomotion abilities. Ruptures in tendons demonstrate strain in elasticity of muscles in the limbs which provides evidence that perhaps the hypothesised ability for the "Procoptodon goliah" to hop may have been unlikely. Due to their locomotive performance, the species may have been vulnerable to human predation. Fossils of giant short-faced kangaroos have been found at the Naracoorte World Heritage fossil deposits in South Australia, Lake Menindee in New South Wales, Darling Downs in Queensland, and at many other sites. A full-size, lifelike replica is on permanent display with other ancient native Australian animals at the Australian Museum.
Perdikas Palaeontological Museum
Though the entire skeleton was found, the bones were not in their proper place, evidently because the beast had been killed here by hunters, who had then dismembered it in order to eat it. The mammoth must have been 5m long and 4m tall. All that is missing is the tusks, which must have been taken away. The skeleton was accompanied by some 30 tools, mostly of quartz, which were used to cut the mammoth up and which came from other parts of the province of Eordaia.
Trirachodon
The skull of "Trirachodon" had a short, narrow snout with a wide orbital region. The zygomatic arches were relatively slender. "Trirachodon" was quite small for a cynodont, growing no larger than 50 cm in length. It had noticeably less molariform teeth than its closely related contemporary "Diademodon". These teeth tended to be transversely broader than "Diademodon" as well. A bony secondary palate and precise postcanine tooth occlusion are seen as derived characteristics in "Trirachodon" that are similar to those of mammals.
Boaz mastodon and Anderson Mills mastodon
Following a heavy rainfall on July 10, 1897, the sons (Harry, Chris, Verne, Clyde) of farmer John Dosch were checking for flood damage along the eastern branch of Mill Creek near the village of Boaz when they discovered some unusual bones sticking out of the creek bank where it had been partially washed away. The boys excavated the bones and displayed them by a hitching post near the road. The local mailman spread the word about the find and the following week stories about it appeared in the "Republican Observer", the "Richland Democrat", and the "Viola Observer". What was described as an arrowhead was found in clay near a rib. The bones were moved to the basement of the Dosch farmhouse. Later, Frank Burnham, a Richland Center, Wisconsin, attorney and member of the state legislature, negotiated the sale of the bones to the State of Wisconsin for fifty dollars. The skeleton, which is about two-thirds complete and missing its tusks, was reconstructed in 1915 by M. G. Mehl and G. M. Schwartz and is housed in the Geology Museum of the University of Wisconsin. It is estimated that the Boaz mastodon was eighteen feet long, stood nine and a quarter feet high, and weighed six to eight tons.
Paralititan
From the formation another sauropod had already been known, "Aegyptosaurus". "Paralititan" differs from "Aegyptosaurus" in its larger size, the latter genus weighing only fifteen tons, possibly in not having pleurocoels in its front tail vertebrae, and in possessing a relatively longer deltopectoral crest on its humerus.
Parabrontopodus
Farlow, in 1992, had given a criterion for classifying sauropod tracks. Traces are distinguished wide as "Brontopodus" (Farlow "et al"., 1989) and the narrow track related to "Breviparopus" (Dutuit "et al"., 1980 "cf". Farlow, 1992). As the "Parabrontopodus" track ratio is 1:5, it is considered narrow by Lockley.These are probably ornithopods. The remains that were attributed to "Parabrontopodus" because they have similar tracks. The size is 45–50 cm.
Pararhabdodon
The proposal that "P. isonensis" was the first known European lambeosaurine was soon challenged, however. In 2001, Jason Head, in a study re-evaluating the status of another species, "Eolambia caroljonesa", as a primitive lambeosaur. Both were determined to instead be more primitive hadrosauroids more basal than the split between Lambeosaurinae and "Hadrosaurinae" (later renamed to Saurolophinae). In regards to "Pararhabdodon", this was based on rebuttal of arguments put forward in the 1999 study; the present anatomy maxilla-jugal articulation was not considered a synapomorphy in Lambeosaurinae, merely the presence of this in the jugal itself, unknown in the species, and the angular deltopectoral crest is a trait present even in primitive iguanodontians. Additionally, its tooth count was lower than those of known lambeosaurs. In the 2006 re-evaluation of the genus by Albert Prieto-Márquez and colleagues, it was included in a phylogenetic analysis for the first time. This found it to be a non-hadrosaurid hadrosauroid, a similar position as had been argued by Head. The cladogram of Prieto-Márquez "et al." (2006) is seen below on the left:
Parahughmilleria
Like other adelophthalmid eurypterids, "Parahughmilleria" was a small-sized eurypterid. The largest species, "P. major", only reached 12.5 cm (5 in), and the smallest species, "P. hefteri", measured only 6 cm (2.4 in), although it has been suggested that these species form different ontogenetic stages (different developmental stages of the same animal throughout its life) of each other. If so, the smallest species would be "P. maria" and "P. bellistriata", both at 7 cm (2.8 in).
Pararhabdodon
In 2013, a maxilla, specimen designation MCD 4919, was referred to "P. isonensis". It possessed synapomorphies of the tsintaosaurin tribe to which "Pararhabdodon" was by that point assigned to, and was referable to "Pararhabdodon" in particular due to rostrocaudally broad rostrocaudal region of the maxilla, a trait unique to "P. isonensis" relative to "Tsintaosaurus", the other named tsintaosaurin taxon. The specimen was discovered at the Serrat del Rostiar 1 locality, part of the "lower red unit" of the Tremp formation just like the type locality, SRA, but in a lower section of the strata, making it older. This extended the range of species further within the upper Maastrichtian. The Serrat del Rostiar 1 locality is near the village of Basturns. In 2019, the new genus and species "Adynomosaurus arcanus" was described, and in the paper describing the referral of MCD 4919 to "P. isonensis" was questioned. The specimen was found to have a differing to the maxilla of the SRA "Pararhabdodon", which would conflict with their identity as belonging to the same species. As the specimen was still recognized as having tsintaosaurin characteristics, the authors still considered it to likely belong to a close relative of "P. isonensis".
Paraphysornis
Its height to the head was approximately and the skull had a length of . The terror bird was slightly smaller than "Brontornis burmeisteri", but larger than "Phorusrhacos longissimus". It lived around 23 million years ago and its fossils were recovered from the Tremembé Formation of the Taubaté Basin. In the Museum of Natural History of Taubaté is exposed the almost complete skeleton of "Paraphysornis" found in 1982 by Herculano Alvarenga.
Hypsilophodon
"Hypsilophodon" was a relatively small dinosaur, though not quite so small as, for example, "Compsognathus". For "Hypsilophodon" often a maximum length of 2.3 metres is stated. This has its origin in a study of 1974 by Galton, in which he extrapolated a length of 2.28 metres based on specimen BMNH R 167, a thigh bone. However, in 2009, Galton concluded that this femur in fact belonged to "Valdosaurus" and downsized "Hypsilophodon" to a maximum known length of 1.8 metres, the largest specimen being NHM R5829 with a femur length of 202 millimetres. Typical specimens are about 1.5 metres long. "Hypsilophodon" would have reached up to half a metre in height. In 2010, Gregory S. Paul estimated a weight of for an animal two metres in length.
Megaraptora
Megaraptorans were medium to large-sized theropods, ranging from "Fukuiraptor", which was about 4.2 meters (14 feet) in length, to the 9 meter (30 feet)-long "Aerosteon", and the 42 foot long "Bahariasaurus", if it is a member. Most megaraptorans are known from very fragmentary remains, although certain characteristics can be identified in multiple members of the clade. At least some megaraptorans, such as "Murusraptor" and "Aerosteon", had extensively pneumatic bones (most noticeably the ilia and ribs), which likely housed sinuses connected to the lungs, similar to modern birds.The slender leg bones and long metatarsals of several species indicate that members of this group likely had cursorial habits. Most megaraptorans are part of the family Megaraptoridae, which was named by Fernando Novas and his colleagues in 2013. This family is united by several adaptations of the ulna and claws which are not present in the basal megaraptoran "Fukuiraptor".
Parasaurolophus
Like most dinosaurs, the skeleton of "Parasaurolophus" is incompletely known. The length of the type specimen of "P. walkeri" is estimated at , and its weight is estimated at . Its skull is about long, including the crest, whereas the type skull of "P. tubicen" is over long, indicating a larger animal. Its single known forelimb was relatively short for a hadrosaurid, with a short but wide shoulder blade. The thighbone measures long in "P. walkeri" and is robust for its length when compared to other hadrosaurids. The upper arm and pelvic bones were also heavily built.
Parabuthus transvaalicus
"Parabuthus transvaalicus" grows to a length of , and is dark brown or black in colour, so it is also known as the Black Thick-Tailed scorpion. Its pincers are thin, but its tail is thickened, with the sting segment being as wide as the rest of the tail. It is nocturnal, resting in a shallow burrow under rocks during the day. It resembles its congener "P. villosus", which is less strictly nocturnal, hairier and has a more westerly distribution. The species is the largest (measuring up to 18 cm) and only diurnal Buthid in the world.
Paranthodon
The holotype of "Paranthodon", BMNH 47338, was found in a layer of the Kirkwood Formation that has been dated between the Berriasian and early Valanginian ages. It consists of the back of the snout, containing the maxilla with teeth, the posterior caudodorsal ramus of the premaxilla, part of the nasals, and some isolated teeth probably from the lower jaw. One additional specimen was assigned to it based on the dentition, BMNH (now NHMUK) R4992, including only isolated teeth sharing the same morphology as those from the holotype. Some bones that were unidentified by Galton & Coombs (1981) were described as a fragment of a vertebrae in 2018 by Raven & Maidment. However, the teeth do not bear any autapomorphies of "Paranthodon", and were referred to an indeterminate stegosaurid in 2008. The teeth were identified in 2018 as also lacking any distinct stegosaurian features, and were thus designated as Thyreophora indeterminate.
Pararhabdodon
Casanovas-Cladellas "et al." revised their position for a final time in 1999, when they published a paper arguing for a position as a primitive member of the hadrosaur subfamily Lambeosaurinae - this made it the first such species known from the continent of Europe. Characters of the skeleton supporting this viewpoint were the truncated and rounded anatomy of the articulation of the maxilla to the jugal, the truncated nature of the back of the maxilla itself, the ventral deflection of the front of the dentary (thought the only known dentary was later referred to a new species, "Koutalisaurus", and later declared that of indeterminate lambeosaurine), its tall neural spines, and of the humerus being distally projected.
Vulcanodon
"Vulcanodon" was a small sauropod. In 2010, Gregory S. Paul estimated its length at eleven metres, its weight at 3.5 tonnes. Some books mention lower estimates of approximately . The thighbone was 110 centimeters long.
Morelladon
"Morelladon" is a medium-sized euornithopod. Its body length has been estimated at six metres, its weight at two tonnes.
Angistorhinus
"Angistorhinus" was another of the early phytosaur genera. It was similar to "Parasuchus" but differed in having the nostrils located further back, towards and above the eyes. This was a more specialized condition that characterized all late phytosaurs. "Angisthorhinus" was a huge animal by any standards; the skull length was generally about 120 cm; estimated overall length to 8 meters, more in "A. megalodon", a very large, short and heavy-muzzled form sometimes given its own genus ("Brachysuchus"), and which far exceeded in size any living crocodile.
Paranthropus robustus
The teeth of these primates were larger and thicker than any gracile australopithecine found, due to the morphology differences Broom originally designated his find as "Australopithecus robustus". On the skull, a bony ridge is located above from the front to back indicating where the jaw muscles joined. "P. robustus" males may have stood only 1.2m (4 feet) tall and weighed 54 kg (120 lb) while females stood just under 1 meter (3 feet 2 inches) tall and weighed only 40 kg (90 lb), indicating a large sexual dimorphism. The teeth found on "P. robustus" are almost as large as those of "P. boisei".
Austroraptor
Considered large for a dromaeosaur, "Austroraptor cabazai" measured about in length from head to tail. In 2010, Gregory S. Paul estimated its length at 6 metres, its weight at 661.387 pounds or 300 kilograms. It is the largest dromaeosaur to be discovered in the Southern Hemisphere. The type specimen, labeled MML-195, consisted of a fragmentary skeleton including parts of the dinosaur's skull, the lower jaws, a few neck and torso vertebrae, some ribs, a humerus, and assorted bones from both legs. However little of the entire skeleton was found, what bones were available for analysis expressed some distinct characteristics that differentiate "Austroraptor" from other dromaeosaurs. "A. cabazai"'s 80 centimeter-long skull was low and elongated, much more so than that of other dromaeosaurs. Several of its skull bones bore some resemblance to that of the smaller troodontid deinonychosaurs. The front limbs of this taxon were short for a dromaeosaur, with its humerus less than half the length of its femur. Among the Dromaeodauridae, only this genus, "Tianyuraptor", "Zhenyuanlong" and "Mahakala" have similarly reduced forelimbs. The relative length of its arms has caused "Austroraptor" to be compared to another, more famous short-armed dinosaur, "Tyrannosaurus".
Matheronodon
Like other rhabodontids, "Matheronodon" would have been a bipedal herbivore. The length of the genus has been estimated at by its lead describer Pascal Godefroit.
Megapiranha
Megapiranha is an extinct serrasalmid characin fish from the Late Miocene (8–10 million years ago) Ituzaingó Formation of Argentina, described in 2009. The type species is "M. paranensis". It is thought to have been about in length. The holotype consists only of premaxillae and a zigzag tooth row; the rest of its body is unknown. This dentition is reminiscent of both the double-row seen in pacus, and the single row seen in the teeth of modern piranhas, suggesting that "M. paranensis" is a transitional form. Its bite force is estimated between .
Paralititan
Paralititan (meaning "tidal giant") was a giant titanosaurian sauropod dinosaur genus discovered in coastal deposits in the Upper Cretaceous Bahariya Formation of Egypt. It lived between 99.6 and 93.5 million years ago.
Albertosaurus
The massive skull of "Albertosaurus", which was perched on a short, S-shaped neck, was about long in the largest adults. Wide openings in the skull (fenestrae) reduced the weight of the head while also providing space for muscle attachment and sensory organs. Its long jaws contained, both sides combined, 58 or more banana-shaped teeth; larger tyrannosaurids possessed fewer teeth, "Gorgosaurus" at least 62. Unlike most theropods, "Albertosaurus" and other tyrannosaurids were heterodont, with teeth of different forms depending on their position in the mouth. The premaxillary teeth at the tip of the upper jaw, four per side, were much smaller than the rest, more closely packed, and D-shaped in cross section. Like with "Tyrannosaurus", the maxillary (cheek) teeth of "Albertosaurus" were adapted in general form to resist lateral forces exerted by a struggling prey. The bite force of "Albertosaurus" was less formidable, however, with the maximum force, by the hind teeth, reaching 3,413 Newtons. Above the eyes were short bony crests that may have been brightly coloured in life and used in courtship to attract a mate.
Parapropalaehoplophorus
Parapropalaehoplophorus septentrionalis was a comparatively small (compared to "Glyptodon") species of glyptodont, extinct relatives of the modern armadillo. The mammal, identified in 2007 from the fossilized remains of a specimen found in 2004, weighed approximately 200 pounds and had a shell covered by tiny circular bumps. It lumbered around northern Chile in the Chucal Formation, an area now dominated by the Andes mountain range, some 18 million years ago. Fossils of the glyptodont also have been found in Peru (Ipururo and Pebas Formations).
Largest prehistoric animals
The largest-known-ever gruiform and largest phorusrhacid or "terror bird" (highly predatory, flightless birds of South America) was "Brontornis", which was about tall at the shoulder, could raise its head above the ground and could have weighed as much as . The immense phorusrhacid "Kelenken" stood tall with a skull long ( of which was beak), had the largest head of any known bird. The largest North American phorusrhacid is "Titanis", which is about tall, as tall as a forest elephant.
Creodonta
During the Central Asia Expedition of 1930 by the American Museum of Natural History, the largest creodont ever discovered was collected: "Sarkastodon mongoliensis". Its dimensions were described as 50% greater than the "Patriofelis" to which it bore many similarities. It has been estimated that "Sarkastodon" attained the body mass of twice the largest American lion.
Sauropoda
Although in general, sauropods were large, a gigantic size ( or more) was reached independently at multiple times in their evolution. Many gigantic forms existed in the Late Jurassic (specifically Kimmeridgian and Turonian), such as the turiasaur "Turiasaurus" and the diplodocoids "Amphicoelias", "Diplodocus" and "Supersaurus". Through the Early to Late Cretaceous, the giants "Sauroposeidon", "Paralititan", "Argentinosaurus", "Puertasaurus", "Antarctosaurus giganteus", "Dreadnoughtus schrani", "Notocolossus" and "Futalognkosaurus" lived, the earliest being a brachiosaurid, with all latter being titanosaurs. One sparsely known possible giant is "Huanghetitan ruyangensis", only known from long ribs. All of the giant genera and species lived in the Late Jurassic to the Late Cretaceous, over a time span of 85 million years, and are independently evolved neosauropods.
Megalodon
Due to fragmentary remains, there have been many contradictory size estimates for megalodon, as they can only be drawn from fossil teeth and vertebrae. Also because of this, the great white shark is the basis of its reconstruction and size estimation, as it is regarded as the best analogue to megalodon. Various size estimates exist for megalodon; in 1973, Hawaiian ichthyologist John E. Randall estimated that the maximum length attained by "C. megalodon" was about , while in the 1990s, marine biologists Patrick J. Schembri and Stephen Papson opined that "C. megalodon" may have approached a maximum of around in total length; Gottfried and colleagues asserted that "C. megalodon" could have reached a maximum of in total length. Nowadays, the commonly acknowledged maximum total length of "C. megalodon" is about , with the average size being , compared to the maximum recorded sizes of the great white shark at and the whale shark (the largest living fish) at . It is possible that different populations of megalodon around the globe had different body sizes and behaviors due to different ecological pressures. If it did attain a size of over , it would have been the largest known fish that has ever lived, surpassing the Jurassic fish "Leedsichthys".
Nigersaurus
Like all sauropods, "Nigersaurus" was a megafaunal quadruped with a small head, thick hind legs, and a prominent tail. Among that clade, "Nigersaurus" was fairly small, with a body length of only and a femur reaching only . It may have weighed around four tonnes, comparable to a modern elephant. It had a short neck for a sauropod, with thirteen cervical vertebrae. Nearly all rebbachisaurids had relatively short necks and a length of or less. The only member of the family that reached the size of larger sauropods was "Rebbachisaurus".
Ornithopod
The early ornithopods were only about 1 metre (3 feet) long, but probably very fast. They had a stiff tail, like the theropods, to help them balance as they ran on their hind legs. Later ornithopods became more adapted to grazing on all fours; their spines curved, and came to resemble the spines of modern ground-feeders such as the bison. As they became more adapted to eating while bent over, they became facultative quadrupeds; still running on two legs, and comfortable reaching up into trees; but spending most of their time walking or grazing while on all fours. The taxonomy of dinosaurs previously ascribed to the Hypsilophodontidae is problematic. The group previously consisted of all non-iguanodontian bipedal ornithischians, but a phylogenetic reappraisal has shown such species to be paraphyletic. As such, the hypsilophodont family is currently represented only by "Hypsilophodon".
Megalodon
Scientists suggest that megalodon looked like a stockier version of the great white shark, though it may have looked similar to the basking shark ("Cetorhinus maximus") or the sand tiger shark ("Carcharias taurus"). Regarded as one of the largest and most powerful predators to have ever lived, fossil remains of megalodon suggest that this giant shark reached a maximum length of with the average size being . Their large jaws could exert a bite force of up to . Their teeth were thick and robust, built for grabbing prey and breaking bone.
Great American Interchange
Metatherians (and a few xenarthran armadillos like "Macroeuphractus") were the only South American mammals to specialize as carnivores; their relative inefficiency created openings for nonmammalian predators to play more prominent roles than usual (similar to the ). Sparassodonts and giant opossums shared the ecological niches for large predators with fearsome flightless "terror birds" (phorusrhacids), whose closest extant relatives are the seriemas. (Similar large terrestrial predatory birds, the bathornithids, were found in North America during the early Cenozoic, but they died out in the Early Miocene, about 20 million years ago.) Through the skies over late Miocene South America (6 Ma ago) soared the largest flying bird known, the teratorn "Argentavis", with a wing span of 6 m or more, which may have subsisted in part on the leftovers of "Thylacosmilus" kills. Terrestrial ziphodont sebecid (metasuchian) crocodyliforms were also present at least through the middle Miocene and maybe to the Miocene-Pliocene boundary. Some of South America's aquatic crocodilians, such as "Gryposuchus", "Mourasuchus" and "Purussaurus", reached monstrous sizes, with lengths up to 12 m (comparable to the largest Mesozoic crocodyliforms). They shared their habitat with one of the largest turtles of all time, the 3.3 m (11 ft) "Stupendemys".
Rhinoceros
Hyracodontidae, also known as "running rhinos", showed adaptations for speed, and would have looked more like horses than modern rhinos. The smallest hyracodontids were dog-sized; the largest was "Paraceratherium", one of the largest known land mammals that ever existed. The hornless "Paraceratherium" was almost seven metres high, ten metres long, and weighed as much as 15 tons. Like a giraffe, it ate leaves from trees. Hyracodontids spread across Eurasia from the mid-Eocene to early Miocene.
JBL Paragon
The original 2-way design consisted of two 150-4C bass drivers with 4-inch coils, and two H5038P-100 elliptical horns. The 5038s are essentially midrange drivers that start rolling off at 15 kHz. In 1960, after feedback from foreign distributors, the Paragon was made into a 3-way loudspeaker by adding two 075 ring radiators (tweeters) mounted in the back of the cabinet and aimed at the central 'sweet spot'. Bass–mid crossover was at 500 Hz and mid–treble frequencies crossed over at 7 kHz.
The Paragon much resembles a sideboard, measures , and weighs according to the product brochure. Standard finishes include korina, birch, mahogany and ebony; premium wood finishes included light and dark walnut, oak, teak, rosewood; a piano lacquer finish would cost extra. A team of six worked on each unit, spending an estimated 112 to 125-man-hours to complete a single unit, most of it spent on finishing of the woodwork. After assembly, eight hours would be needed just for sanding down the entire enclosure. Then, several coats of varnish are applied by hand, allowed to dry, and then smoothed down by further rubbing.
The components used in the Paragon went through numerous changes over the years.
Metriacanthosaurus
"Metriacanthosaurus" was a medium-sized theropod with a femur length of . Gregory S. Paul in 1988 estimated its weight at . "Metriacanthosaurus" was named for the height of its neural spines, which are actually not overly tall for theropods. They are similar to other theropods such as "Megalosaurus", "Sinraptor", and "Ceratosaurus" in being 1.5 times the height of the centrum.
Megaraptor
"Megaraptor" was initially described as a giant dromaeosaur, known primarily from a single claw (about 30 cm long) that resembled the sickle-shaped foot claw of dromaeosaurids. The discovery of a complete front limb, however, showed that this giant claw actually came from the first finger of the hand. In 2010, Gregory S. Paul estimated its length at , its weight at . The hands were unusually elongated, bearing sickle-shaped claws even more recurved than those of spinosaurids.
Orkoraptor
"Orkoraptor" was a medium-sized theropod. In 2010, Gregory S. Paul estimated its length as and mass as 500 kilograms. The holotype, MPM-Pv 3457 was excavated in 2001 and consists of a right postorbital, a right quadratojugal, a probable right coronoid, eight isolated teeth, the intercentrum of the atlas and its right neurapophysis, two proximal caudal vertebrae, the proximal half of the right tibia, eight fragmentary ribs, and three incomplete chevrons. It was initially believed to be a coelurosaur due to the upturned anterior process of the postorbital as well as specialized teeth which are unserrated on the mesial (front) side and have an 8-shaped cross section, similar to those of dromaeosaurids and compsognathids. However, many other features contradict those of these families and other coelurosaurs, so its original describers were unable to conclusively assign it to any specific family. They did note its similarity to a then-undescribed Patagonian theropod now known as "Murusraptor". More recent analyses have explained that these coelurosaur-like traits are also present in some megaraptorans. For example, "Orkoraptor"'s postorbital is almost identical to that of "Aerosteon" and the juvenile "Megaraptor" described in 2014 has teeth similar to those of "Orkoraptor".
Pararhabdodon
The same 2006 study, by Albert Prieto-Márquez and colleagues, noted that no dentary had been found at the SRA locality to compare to the LL specimen, and so they restricted "P. isonensis" to material known from its original locality. Additionally, they named a genus and species for IPS SRA 27, "Koutalisaurus kohlerorum". The generic name is derived from the Greek word "koutali", meaning spoon, in reference to the shape the jaw of the animal would've had, and the specific name honours Terry and Mary Kohler, for their support of vertebrate paleontology. One autapomorphy (unique trait) was used to diagnose the taxon as a new species: a very elongated edentulous section on the dentary, which was medially (inwardly) extended. No teeth were preserved, but there are 35 tooth positions. Several other European hadrosaur dentaries were compared based on published data, and the specimen was found to be unique compared to all of them. Though the specimen proved too fragmentary to be used for phylogenetic analysis, it was determined to be a hadrosaurid of some kind, more derived than "Pararhabdodon", considered the sister taxon to Hadrosauridae. The authors noted the possibility future discoveries could lead to synonymization of their taxon with "P. isonensis"
Paradoxides
Paradoxides is a genus of large to very large trilobites found throughout the world during the Mid Cambrian period. One record-breaking specimen of "Paradoxides davidis" is . It has a semicircular head, free cheeks each ending with a long, narrow, recurved spine, and sickle-shaped eyes, providing almost 360° view, but only in the horizontal plane. Its elongated trunk was composed of 19-21 segments and was adorned with longish, recurved lateral spines. Its pygidium (caudal shield) was comparatively small. "Paradoxides" is a characteristic Middle Cambrian trilobite of the 'Atlantic' (Avalonian) fauna. Avalonian rocks were deposited near a small continent called Avalonia in the Paleozoic Iapetus Ocean. Avalonian beds are now in a narrow strip along the East Coast of North America, and in Europe.
Albertosaurus
As a tyrannosaurid, "Albertosaurus" was a bipedal predator with tiny, two-fingered hands and a massive head that had dozens of large, sharp teeth. It may have been at the top of the food chain in its local ecosystem. While "Albertosaurus" was large for a theropod, it was much smaller than its larger and more famous relative "Tyrannosaurus rex", growing nine to ten meters long and possibly weighing less than 2 metric tons.
Megalodon
The dental formula of megalodon is: . As evident from the formula, megalodon had four kinds of teeth in its jaws: anterior, intermediate, lateral, and posterior. Megalodon's intermediate tooth technically appears to be an upper anterior and is termed as "A3" because it is fairly symmetrical and does not point mesially (side of the tooth toward the midline of the jaws where the left and right jaws meet). Megalodon had a very robust dentition, and had over 250 teeth in its jaws, spanning 5 rows. It is possible that large megalodon individuals had jaws spanning roughly across. The teeth were also serrated, which would have improved efficiency in cutting through flesh or bone. The shark may have been able to open its mouth to a 75° angle, though a reconstruction at the USNM approximates a 100° angle.
In 2008, a team of scientists led by S. Wroe conducted an experiment to determine the bite force of the great white shark, using a long specimen, and then isometrically scaled the results for its maximum size and the conservative minimum and maximum body mass of megalodon. They placed the bite force of the latter between in a posterior bite, compared to the bite force for the largest confirmed great white shark, and for the placoderm fish "Dunkleosteus". In addition, Wroe and colleagues pointed out that sharks shake sideways while feeding, amplifying the force generated, which would probably have caused the total force experienced by prey to be higher than the estimate.
Xenoposeidon
Like other sauropods, "Xenoposeidon" would have been a large quadrupedal herbivore. It was relatively small for a sauropod. Extrapolating from the vertebra suggests that the type individual of "Xenoposeidon" could have been about 15 metres (50 ft) long and weighed approximately 7.6 tonnes (8.4 short tons), if it resembled "Brachiosaurus", to 20 m (65 ft) long and 2.8 tonnes (3.1 short tons), if it was built like the longer, lighter "Diplodocus".
Sauroposeidon
The original "Sauroposeidon" find was composed of four articulated, mid-cervical vertebrae (numbers 5 to 8), with the cervical ribs in place. The vertebrae are extremely elongated, with the largest one having an overall length of , making it the longest sauropod neck vertebra on record. Examination of the bones revealed that they are honeycombed with tiny air cells, and are very thin, like the bones of a chicken or an ostrich, making the neck lighter and easier to lift. The cervical ribs were remarkably long as well, with the longest measurable rib (on vertebra 6) measuring – about 18% longer than the longest rib reported for "Giraffatitan", but exceeded in length by the cervical ribs of "Mamenchisaurus".
Estimates of "Sauroposeidon"'s size are based on a comparison between the four "Sauroposeidon" vertebrae and the vertebrae of the HM SII specimen of "Giraffatitan brancai", located in the Berlin's Natural History Museum. The HM SII is the most complete brachiosaur known, though since it is composed of pieces from different individuals its proportions may not be totally accurate. Comparisons to the other relatives of "Sauroposeidon" are difficult due to limited remains.
The neck length of "Sauroposeidon" is estimated at , compared to a neck length of for the HM SII "Giraffatitan". This is based on the assumption that the rest of the neck has the same proportions as "Giraffatitan", which is a reasonably good conjecture.
Machairodus
"Machairodus" was similar in size to a modern lion, standing about at the shoulder. The species once referred to "Machairodus coloradensis" was apparently significantly larger, about at the shoulder, according to skeletal and life reconstructions. If accurate, this would have made "M. coloradensis" one of the largest felids. However "M. coloradensis", along with "M. kurteni" and "M. giganteus", has been reassigned to the genus "Amphimachairodus" and by extent, the Homotherini based on both morphology and its time of appearance in North America. "Nimravides catacopsis" also has been separated from "Machairodus", as the two are too different in regards to autapomorphies to be synonymous. However, the species "Machairodus horribilis", which stands as the largest known species of the genus, is comparable in size to the much later "Smilodon populator", weighing in at around . Its skull, measuring upwards of in length, is the largest known skull for any machairodont.
Austroposeidon
"Austroposeidon" was a large sauropod, with the only known specimen, an adult, having a length of about - in fact, it is the largest dinosaur discovered in Brazil to date.
Paragodon
Paragodon paragoides is a small (4–5 mm) hoverfly which differs from other hoverflies by its simple male genitalia, and was accordingly considered the most primitive microdontine species. It is the sole member of the genus Paragodon, as the other known species was removed to a separate genus, "Surimyia".
Paracentropogon longispinis
The size of this fish is up to . Its body is compressed laterally and is endowed with a dorsal fin starting from the top of the head until joining practically the superior base of the caudal fin. When the dorsal fin is spread, it looks like a toothed crest. The 12 to 15 spines of the dorsal fin are venomous, and it has seven or eight soft rays. It remains in the substratum and moves using its pectoral fins. Its body color is mainly red-brown with one or two bright white spots above the lateral line and it "wears" a bright white mask starting from the top of its head to the inferior lip. Individuals from Thailand have large dark blotches over the body, while those from Indonesia and Australia are usually more mottled. It is able to change its color from lighter to darker to a certain extent. In appearance, it is somewhat similar to the cockatoo waspfish, "Ablabys taenianotus".
Sauropoda
The best evidence indicates that the most massive were "Argentinosaurus" (120 metric tons), "Puertasaurus" (80 to 100 metric tons ), "Alamosaurus", "Paralititan", "Antarctosaurus" (69 metric tons). There was poor (and now missing) evidence that so-called "Bruhathkayosaurus", might have weighed over 175 metric tons but this has been questioned. The weight of "Amphicoelias fragillimus" was estimated at 122.4 metric tons but 2015 research argued that these estimates may have been highly exaggerated. The largest land animal alive today, the Savannah elephant, weighs no more than .
Spinosauridae
Although reliable size and weight estimates for most taxa are hindered by the lack of good material, all known spinosaurids were large animals. The smallest, "Irritator", was between 6 and 8 meters in length and 1 tonne (1.1 short tons) in weight. While "Ichthyovenator", "Baryonyx", and "Suchomimus" ranged from 7.5 to 11 meters long, and weighing between 1 and 5.2 tonnes (1.2 and 5.7 short tons). "Spinosaurus" was the largest, capable of reaching lengths over 15 meters (49 ft) and weighing between 7 and 20.9 tonnes (7.7 and 23.0 short tons),even though the latest estimates suggest a weight of 6.4–7.2 tonnes (7.1–7.9 short tons). This consistency in large body size among spinosaurids could have evolved as a byproduct of their preference for semiaquatic lifestyles, as without the need to compete with other large theropods for food, they would have been able to grow to tremendous lengths.
Paranthodon
"Paranthodon" was a small relative of larger stegosaurids such as "Stegosaurus". Thomas R. Holtz Jr. estimated that the animal was long and weighed between . The snout is elongated, though not extremely so, and convex on top. The back of the premaxilla is long and broad, and the external nares are large. The teeth have a prominent primary ridge. The fossilized nasal and maxillary bones are relatively complete, and an incomplete premaxilla is also preserved. The partial snout resembles "Stegosaurus" in its large posterior premaxillary process and the extension of the palate. However, "Stegosaurus" was the only stegosaurid known from adequate cranial material to compare with "Paranthodon" during the 1981 review of the taxon, and even though their resemblance is great, tooth morphology is very distinguishing among the stegosaurians. For example, cranial material is known from "Stegosaurus", "Paranthodon", "Kentrosaurus", and "Tuojiangosaurus", and the tooth morphology differs in all of them.
Sturgeon
Sturgeon is the common name for the 27 species of fish belonging to the family Acipenseridae. Their evolution dates back to the Triassic some 245 to 208 million years ago. The family is grouped into four genera: "Acipenser", "Huso", "Scaphirhynchus" and "Pseudoscaphirhynchus". Four species may now be extinct. Two closely related species, "Polyodon spathula" (American paddlefish) and "Psephurus gladius" (Chinese paddlefish, possibly extinct) are of the same order, Acipenseriformes, but are in the family Polyodontidae and are not considered to be "true" sturgeons. Both sturgeons and paddlefish have been referred to as "primitive fishes" because their morphological characteristics have remained relatively unchanged since the earliest fossil record. Sturgeons are native to subtropical, temperate and sub-Arctic rivers, lakes and coastlines of Eurasia and North America. 
Sturgeons are long-lived, late-maturing fishes with distinctive characteristics, such as a heterocercal caudal fin similar to that of sharks, and an elongated spindle-like body that is smooth-skinned, scaleless and armored with 5 lateral rows of bony plates called scutes. Several species can grow quite large, typically ranging 7–12 feet (2-3½ m) in length. The largest sturgeon on record was a Beluga female captured in the Volga estuary in 1827, weighing and long. Most sturgeons are anadromous bottom-feeders which migrate upstream to spawn but spend most of their lives feeding in river deltas and estuaries. Some species inhabit freshwater environments exclusively while others primarily inhabit marine environments near coastal areas, and are known to venture into open ocean.
Giganotosaurus
In 1996, the palaeontologist Paul Sereno and colleagues described a new skull of the related genus "Carcharodontosaurus" from Morocco, a theropod described in 1927 but previously known only from fragmentary remains (the original fossils were destroyed in World War II). They estimated the skull to have been long, similar to "Giganotosaurus", but perhaps exceeding that of the "Tyrannosaurus" "Sue", with a 1.53 m (5 ft) long skull. They also pointed out that carcharodontosaurs appear to have had the proportionally largest skulls, but that "Tyrannosaurus" appears to have had longer hind limbs. In a 1995 interview for a "Science News" article entitled "New Beast Usurps "T. Rex" as King Carnivore", Sereno noted that these newly discovered theropods from South America and Africa competed with "Tyrannosaurus" as the largest predators, and would help in the understanding of Late Cretaceous dinosaur faunas, which had otherwise been very "North America-centric". In the same issue of "Science" in which "Carcharodontosaurus" was described, the palaeontologist Philip J. Currie cautioned that it was yet to be determined which of the two animals were larger, and that the size of an animal is less interesting to palaeontologists than, for example, adaptations, relationships, and distribution. He also found it remarkable that the two animals were found within a year of each other, and were closely related, in spite of being found on different continents. 
In a 1997 "Science News" interview, Coria estimated "Giganotosaurus" to have been 13.7 (45 ft) to 14.3 (47 ft) m long and weighing based on new material, larger than "Carcharodontosaurus". Sereno countered that it would be difficult to determine a size range for a species based on few, incomplete specimens, and both palaeontologists agreed that other aspects of these dinosaurs were more important than settling the "size contest". In 1998, the palaeontologist Jorge O. Calvo and Coria referred a partial left dentary containing some teeth (MUCPv-95) to "Giganotosaurus". It had been collected by Calvo near Los Candeleros in 1988 (found in 1987), who described it briefly in 1989, while noting it may have belonged to a new theropod taxon. Calvo and Coria found the dentary to be identical to that of the holotype, though 8% larger at 62 cm (24 in). Though the rear part of it is incomplete, they proposed that the skull of the holotype specimen would have been long, and estimated the skull of the larger specimen to have been long, the longest skull of any theropod.
Hyracodon
It was a lightly built, pony-like mammal of about 1.5 m (5 ft) long. "Hyracodon"'s skull was large in comparison to the rest of the body. "Hyracodon's" dentition resembled that of later rhinoceroses, but it was a much smaller animal and differed very little in appearance from the primitive horses of which it was a contemporary (32–26 million years ago). It had a short, broad snout and its long, slender limbs had three digits.
Like the primitive horses, hyracodonts inhabited open forests and wooded steppes and turned from browsing foliage to grazing grass. They died out without leaving any descendants and they mark the end of the phylogenetic branch of hornless, running rhinoceroses.
Ernanodon
It was a relatively small animal about 50 cm in length, not including the tail. When it was first discovered and examined, it was thought to be a primitive anteater. "E. antelios" and "Eurotamandua" of Eocene Germany helped to support a now-abandoned hypothesis that there was movement between the faunas of South America (the homeland of anteaters and other Xenarthrans), and the faunas of Europe and Asia, by way of North America. This was further supported by the alleged European Phorusrhacid "Strigogyps", also of Eocene Germany.
Eilenodon
"Eilenodon robustus" is the type species of Eilenodontinae, a subfamily of Opisthodontia. It and other eilenodonts had very wide and strongly packed teeth as well as a deep jaw for chewing and shredding plant material. It is primarily known from an incomplete pair of lower jaws approximately 5 centimeters (2 inches) long. If the jaws were complete, they would have been about 10 centimeters (4 inches) long, signifying that "Eilenodon robustus" was among the largest species of rhynchocephalians known, surpassed only by its fellow eilenodont "Priosphenodon avelasi". Among all other sphenodonts, "Eilenodon" is most similar to "Toxolophosaurus", another eilenodont which was redescribed the same year as "Eilenodon's" description. Even so, there are some differences between the two taxa.
Pararhabdodon
Initially, the material was thought to belong to a rhabdodontid dinosaur, or some other similar type of primitive iguanodontian. Later discoveries of additional material revealed its true nature as a hadrosaur. Its placement within the group remained controversial - in 1999 it was proposed it belonged to the subfamily Lambeosaurinae, making it the first known from the continent of Europe. Later studies questioned this, instead classifying it as a more primitive hadrosauroid. In 2009 evidence was put forward that it was indeed a lambeosaurine, and more specifically a close relative of "Tsintaosaurus", a genus from China. This position has been consistently found since, and the group containing them was later named Tsintaosaurini.
Megalohyrax
This animal was very different from the current hyraxes and much larger, generally reaching the size of a tapir and sometimes exceeding 1.5 meters in length. The legs were strong and the body very massive. The skull was long and low, unlike that of today's hyraxes, and could reach 40 centimeters in length. The dental formula of "Megalohyrax" was composed of three incisors, one canine, four premolars and three molars.
Parabathymyrus brachyrhynchus
Parabathymyrus brachyrhynchus is an eel in the family Congridae (conger/garden eels). It was described by Henry Weed Fowler in 1934, originally under the genus "Ariosoma". It is a marine, deep water-dwelling eel which is known from the western central Pacific Ocean. It dwells at a maximum depth of 289 metres. Males can reach a maximum total length of 33 centimetres.
Saltriovenator
Because of the fragmentary nature of the remains, it was impossible to directly measure the size of the animal. The describing authors therefore compared the fossils with those of two theropods of a roughly similar volume. Comparing with the skeletal elements of MOR 693, a "Allosaurus fragilis" specimen, they conservatively concluded that the "Saltriovenator" holotype individual was at least seven to eight metres long. This would make "Saltriovenator" the largest known theropod living before the Aalenian stage, 25% longer than "Ceratosaurus" from the late Jurassic. Comparing with "Ceratosaurus" itself, resulted in a body length of 730 centimetres, a hip height of 220 centimetres and a skull length of eighty centimetres. The thighbone length would then have been about eighty to eighty-seven centimetres, which indicates a body weight of 1160 to 1524 kilogrammes. Another method consisted in extrapolating from the known length of the forelimb. Applying the usual limb ratio indicated a hindlimb length of 198 centimetres. The thighbone would then have been 822 to 887 millimetres long, indicating a weight of 1269 to 1622 kilogrammes.
Valdosaurus
In 2009 however, Galton critically reviewed the "Valdosaurus" material. He concluded that no fossils from outside England could be reliably referred to the genus. He thus gave "V. nigeriensis" its own genus: "Elrhazosaurus". Even of many of the English specimens it was uncertain whether they belonged to "Valdosaurus", including all cranial elements and teeth. Some hindlimb and pelvis bones from the Upper Wealden Clay Formation (late Barremian) were referable to "V. canaliculatus". Some material from the earlier Hastings Beds (Valanginian) were referred to a "Valdosaurus" sp. Galton established that Richard Owen had in 1842 been the first to describe "Valdosaurus" thighbones, specimens BMB 004297-004300, assigning them to "Iguanodon". Galton emphasized that though the type femora were very small, fourteen centimetres long (which has led to estimates of a length of 1.2 metres and a weight of ten kilograms), these were from a juvenile individual and that an adult would have been a "medium-sized euornithopod", with some thighbones reaching a length of half a metre.
Largest prehistoric animals
The largest-known ichthyosaur was "Shastasaurus sikanniensis" at in length. In April 2018, paleontologists announced the discovery of a previously unknown ichthyosaur that may have reached lengths of 26 m (85 ft)- 30 m (100 feet long) making it one of the largest animals known, rivaling the Blue Whale in size. Another giant Ichthyosaur was found as well and it was larger than Lilstock Monster, possibly surpassing Blue Whale in size.The heavy built "Moradisaurus grandis", with a length of , is the largest known captorhinid.
Pteranodon
Methods used to estimate the mass of large male "Pteranodon" specimens (those with wingspans of about 7 meters) have been notoriously unreliable, producing a wide range of estimates from as low as to as high as . In a review of pterosaur size estimates published in 2010, researchers Mark Witton and Mike Habib demonstrated that the latter, largest estimates are almost certainly incorrect given the total volume of a "Pteranodon" body, and could only be correct if the animal "was principally aluminium". Witton and Habib considered the methods used by researchers who obtained smaller mass estimates equally flawed. Most have been produced by scaling modern animals such as bats and birds up to "Pteranodon" size, despite the fact that pterosaurs have vastly different body proportions and soft tissue anatomy from any living animal.
Paraplacodus
Like all known Placodonts, "Paraplacodus" was an aquatic reptile that fed almost exclusively on shellfish. Most known Placodont species can be divided into two groups - the unarmored placodontoids, which would resemble a large, scaly, tooth-filled newt, or the armored cyamodontids, which would resemble a heavily armored turtle; "Paraplacodus" belonged to the former family. It grew to a length of .
Evolution of dinosaurs
These evolved into the sauropods which became gigantic quadrupedal herbivores, some of which reached lengths of at least 26 m (85 ft). Features defining this clade include a ratio of forelimb length to hindlimb length greater than 0.6. Most sauropods still had hindlimbs larger than forelimbs; one notable exception is "Brachiosaurus" whose long forelimbs suggest that it had evolved to feed from tall trees like a modern-day giraffe.
Bruhathkayosaurus
By comparison, the titanosaur "Argentinosaurus" is estimated to have reached in length, and to have weighed 80–100 tons. Another huge titanosaurid, "Paralititan", was probably long, and weighed 59–80 tons. All of these sauropods are known only from partial or fragmentary remains, so the size estimates are uncertain. Length is calculated by comparing existing bones to the bones of similar dinosaurs, which are known from more complete skeletons and scaling them up isometrically. However, such extrapolation can never be more than an educated guess and the length of the tail, in particular, is often hard to judge. Determining mass is even more difficult, because little evidence of soft tissues survives in the fossil record. In addition, isometric scaling is based on the assumption that body proportions remain the same, which is not necessarily the case. In particular, the proportions of the titanosaurs are not well known, due to a limited number of relatively complete specimens.
Hypsilophodon
Modern research of "Hypsilophodon" began with the studies of Peter Malcolm Galton, starting with his thesis of 1967.
Although new finds continue to be made, most known "Hypsilophodon" specimens were discovered between 1849 and 1921 and are in the possession of the Natural History Museum that acquired the collections of Mantell, Fox, Hulke and Hooley. These represent about twenty individual animals. Apart from the holotype and paratype, the most significant specimens are: NHM R5829, the skeleton of a large animal; NHM R5830 and NHM R196/196a, both skeletons of juvenile animals; and NHM R2477, a block with a skull together with two separate vertebral columns. Fossils from other locations, especially from the mainland of southern Great Britain, Portugal and Spain, have once been referred to "Hypsilophodon". However, in 2009 Galton concluded that the specimens from Great Britain proper were either indeterminable or belonged to "Valdosaurus", and that the fossils from the rest of Europe were those of related but different species. This leaves the finds on Isle of Wight, off the south coast of England, as the only known authentic "Hypsilophodon" fossils. The fossils have been found in the "Hypsilophodon Bed", a one metre thick marl layer surfacing in a 1200 metre long strip along the Cowleaze Chine parallel to the southwest coast of Wight, part of the upper Wessex Formation and dating to the late Barremian, about 126 million years old. Reports that "Hypsilophodon" would be present in the later Vectis Formation, Galton in 2009 considered as unsubstantiated.
Megalosaurus
Since the first finds, many other "Megalosaurus" bones have been recovered; however, no complete skeleton has yet been found. Therefore, the details of its physical appearance cannot be certain. However, a full osteology of all known material was published in 2010 by Benson.
Traditionally, most texts, following Owen's estimate of 1841, give a body length of thirty feet or nine metres for "Megalosaurus". The lack of an articulated dorsal vertebral series makes it difficult to determine an exact size. David Bruce Norman in 1984 thought "Megalosaurus" was seven to eight metres long. Gregory S. Paul in 1988 estimated the weight tentatively at 1.1 tonnes, given a thighbone seventy-six centimetres long. The trend in the early twenty-first century to limit the material to the lectotype inspired even lower estimates, disregarding outliers of uncertain identity. Paul in 2010 stated "Megalosaurus" was six metres long and seven hundred kilogrammes heavy. However, the same year Benson claimed that "Megalosaurus", though medium-sized, was still among the largest of Middle Jurassic theropods. Specimen BMNH 31806, a thighbone 803 millimetres long, would indicate a body weight of 943 kilogrammes, using the extrapolation method of J.F. Anderson — which method, optimised for mammals, tends to underestimate theropod masses by at least a third. Furthermore, thighbone specimen OUM J13561 has a length of about eighty-six centimetres.
Pararhabdodon
In their 1997 paper, Laurent and colleagues referred additional remains (jaw material, vertebrae, and limb bones of multiple individuals of different ages) from the Le Bexen site of the uppermost Cretaceous of Aude, southern France, to the genus. Prieto-Márquez and colleagues commented on this referral in a 2006 paper, though noting they had not examined the material themselves. They concluded all of the specimens, excepting one fragmentary humerus, were too poorly preserved to allow proper comparison with the Spanish "Pararhabdodon" material, and so disagreed with the referral. Of the humerus, they found it was distinguishable from "P. isonensis", and so also not referable to the species. A group composed of some of the same authors as the 2006 study, including Prieto-Márquez, investigated the material first hand for a 2013 re-evaluation of all European lambeosaurine material, and supported their previous conclusions. Laurent had, in a 2003 dissertation, referred more French lambeosaurine material to "Pararhabdodon"; in this case, material held at the Musée des Dinosaures d’Espéraza. The referral was made as the genus was, at that point, the only lambeosaurine named from the continent. Prieto-Márquez "et al." (2013) used this material to establish their new taxon, "Canardia garonnensis".
1857 Parchomenko
According to the survey carried out by NASA's Wide-field Infrared Survey Explorer with its subsequent NEOWISE mission, "Parchomenko" measures 7.99 and 9.84 kilometers in diameter, and its surface has an albedo of 0.295 and 0.333, respectively. The "Collaborative Asteroid Lightcurve Link" assumes a standard albedo for stony asteroids of 0.20 and calculates a diameter of 8.5 kilometers, based on an absolute magnitude of 12.4.
Metriorhynchus
Even though "Metriorhynchus" was an effective predator, it was vulnerable to predation from apex predators such as "Liopleurodon" which could grow to 6.39 meters (21 feet) in length. Since "Metriorhynchus" had lost its osteoderms, "armour scutes", to become more efficient swimmers it would have had little defense against larger marine predators.
Corythosaurus
Benson "et al." (2012) estimated that "Corythosaurus" has an average length of . Richard Swann Lull's earlier length estimate, published in 1942, found a slightly longer total length of , a size similar to "Lambeosaurus lambei", another Canadian lambeosaurine. In 1962, Edwin H. Colbert used models of specific dinosaurs, including "Corythosaurus", to estimate their weight. The "Corythosaurus" model used, was modelled by Vincent Fusco after a mounted skeleton, and supervised by Barnum Brown. After testing, it was concluded that the average weight of "Corythosaurus" was . More recent size estimates of "Corythosaurus", published in 2001, find the genus to be among the largest hadrosaurids, only smaller than "Shantungosaurus" and "Parasaurolophus". The total length of "Corythosaurus" specimen AMNH 5240 was found to be , with a weight of .
Paralititan
Little of "Paralititan" is known, so its exact size is difficult to estimate. However, the limited material, especially the long humeri, suggested that it is one of the most massive dinosaurs ever discovered, with an estimated weight of . The complete right humerus measured 1.69 meters (5.54 ft) long which at the time of discovery was the longest known in a Cretaceous sauropod; this was surpassed in 2016 with the discovery of "Notocolossus" which had a 1.76 m (5 ft 9 in) humerus. Using "Saltasaurus" as a guide, Carpenter estimated its length at around . Scott Hartman estimates an animal that is massive, but still smaller than the biggest titanosaurs such as "Puertasaurus", "Alamosaurus", and "Argentinosaurus". In 2010, Gregory S. Paul estimated the length at twenty metres, the weight at twenty tonnes.
Sauropoda
Among the smallest sauropods were the primitive "Ohmdenosaurus" (4 m, or 13 ft long), the dwarf titanosaur "Magyarosaurus" (6 m or 20 ft long), and the dwarf brachiosaurid "Europasaurus", which was 6.2 meters long as a fully-grown adult. Its small stature was probably the result of insular dwarfism occurring in a population of sauropods isolated on an island of the late Jurassic in what is now the Langenberg area of northern Germany. The diplodocoid sauropod "Brachytrachelopan" was the shortest member of its group because of its unusually short neck. Unlike other sauropods, whose necks could grow to up to four times the length of their backs, the neck of "Brachytrachelopan" was shorter than its backbone.
Paraves
The most extreme examples of miniaturization and progenesis are found in Paraves. The ancestors of Paraves first started to shrink in size in the early Jurassic 200 million years ago, and fossil evidence shows that this theropod line evolved new adaptations four times faster than other groups of dinosaurs, and was shrinking 160 times faster than other dinosaur lineages were growing. Turner "et al". (2007) suggested that extreme miniaturization was ancestral for the clade, whose common ancestor has been estimated to have been around 65 centimeters long and 600-700 grams in mass. In Eumaniraptora, both Dromaeosauridae and Troodontidae went later through four independent events of gigantism, three times in dromaeosaurids and once in troodontids, while the body mass continued to decrease in many forms within Avialae. Fossils show that all the earliest members of Paraves found to date started out as small, while Troodontidae and Dromaeosauridae gradually increased in size during the Cretaceous period.
Protohadros
Due to the paucity of the remains much of the reconstruction of this dinosaur is speculative. The skull is about seventy centimetres long. From this Head estimated the length of the type specimen of "Protohadros" at seven to eight metres. He pointed out that this specimen was that of a subadult and that fully-grown individuals could have been longer. "Protohadros" had a massive, very deep set of lower jaws, and the snout was strongly turned down at the front, which according to Head suggested a habit of grazing on low-growing plants, rather than browsing from bushes or overhanging branches. Its diet would then have consisted of the swamp plants which grew in the delta streams in its habitat, scooped up by the broad, down-turned mouth. In some respects "Protohadros" was intermediate in morphology to more derived hadrosaurids. Like these it did have pleurokinesis, a cranial joint system that produced the food-grinding action, but only partially in that the quadrate at the back of the skull was still relatively immobile.
Pararhabdodon
The stratigraphic layer where the bonebed was found is in thickness. Around 95% of all remains from the site belong to dinosaurs; nearly all identified specimens from this sample belong to hadrosaurs. Of prepared material, 270 skeletal elements can confidently be identified as belonging to hadrosauroids. The number of hadrosaur specimens from the site in total could number over 500, and possibly as much as 900. In addition to the large numbers of fossils of the animals themselves, the BP locality is one of many sites from the Tremp Syncline where hadrosaurs tracks have been found. At least one track is preserved at the site, in a sandstone block from a stratigraphic level similar to that of the bonebed. It is the richest hadrosaur bonebed ever found in Europe, and the largest ever found in one palaeoinsular locale; as such, it is the most important hadrosauroid site of the eastern Tremp Syncline.
Rhabdodon
"Rhabdodon" was probably an important herbivore in Cretaceous Europe. "Rhabdodon's" predators may include the potentially dubious abelisaur "Tarascosaurus", and young may have been prey for "Pyroraptor"; thought adults where probably too big for either; as "Tarascosaurus" was around 2.5–3 m (7–10 ft), "Pyroraptor" around 2 m (6–7 ft), and "Rhabdodon" 6 m (18–20 ft).
Carcharodontosauridae
Carcharodontosaurids (from the Greek καρχαροδοντόσαυρος, "carcharodontósauros": "shark-toothed lizards") were a group of carnivorous theropod dinosaurs. In 1931 Ernst Stromer named Carcharodontosauridae as a family, which, in modern paleontology, indicates a clade within Carnosauria. Carcharodontosaurids included some of the largest land predators ever known: "Giganotosaurus", "Mapusaurus", "Carcharodontosaurus", and "Tyrannotitan" all rivaled or slightly exceeded "Tyrannosaurus" in length. A 2015 paper by Christophe Hendrickx and colleagues gives a maximum length estimate of 14 meters (46 feet) for the largest carcharodontosaurids, while the smallest carcharodontosaurids were estimated to have been at least 6 meters (20 feet) long.
Dilophosaurus
"Dilophosaurus" was one of the earliest large predatory dinosaurs, a medium-sized theropod, though small compared to some of the later theropods. Slender and lightly built, its size was comparable to that of a brown bear. The largest known specimen weighed about , measured about in length, and its skull was long. The smaller holotype specimen weighed about , was long, with a hip height of about , and its skull was long. A resting trace of a theropod similar to "Dilophosaurus" and "Liliensternus" has been interpreted by some researchers as showing impressions of feathers around the belly and feet, similar to down. Other researchers instead interpret these impressions as sedimentological artifacts created as the dinosaur moved, though this interpretation does not rule out that the track-maker could have borne feathers.
Paraves
Most theropods walked with three toes contacting the ground, but fossilized footprint tracks confirm that many basal paravians, including dromaeosaurids, troodontids, and some early avialans, held the second toe off the ground in a hyperextended position, with only the third and fourth toes bearing the weight of the animal. This is called functional didactyly. The enlarged second toe bore an unusually large, curved sickle-shaped claw (held off the ground or 'retracted' when walking). This claw was especially large and flattened from side to side in the large-bodied predatory eudromaeosaurs. In these early species, the first toe (hallux) was usually small and angled inward toward the center of the body, but only became fully reversed in more specialized members of the bird lineage. One species, "Balaur bondoc", possessed a first toe which was highly modified in parallel with the second. Both the first and second toes on each foot of "B. bondoc" were held retracted and bore enlarged, sickle-shaped claws.
Dinosaur size
The sauropods were the largest and heaviest dinosaurs. For much of the dinosaur era, the smallest sauropods were larger than anything else in their habitat, and the largest were an order of magnitude more massive than anything else that has since walked the Earth. Giant prehistoric mammals such as "Paraceratherium" and "Palaeoloxodon" (the largest land mammals ever) were dwarfed by the giant sauropods, and only modern whales surpass them in size. There are several proposed advantages for the large size of sauropods, including protection from predation, reduction of energy use, and longevity, but it may be that the most important advantage was dietary. Large animals are more efficient at digestion than small animals, because food spends more time in their digestive systems. This also permits them to subsist on food with lower nutritive value than smaller animals. Sauropod remains are mostly found in rock formations interpreted as dry or seasonally dry, and the ability to eat large quantities of low-nutrient browse would have been advantageous in such environments.
Barylambda
In life, "Barylambda" probably resembled a large tapir, with a small head and long, well-developed tail and bear-like legs. The length was about 2.5 meters with a weight around 650 kg, about the size of a pony. "Barylambda" was large even for a pantodont, sheer size probably protecting it from contemporary carnivores.
Alexandrine parakeet
The Alexandrine parakeet is one of the largest parakeets, measuring from the top of the head to the tip of the tail and weighing . The tail measures . It is predominantly green with a light blue-grey sheen on the cheeks and nape (back of the neck), yellow-green abdomen, red patch on the shoulders and massive red beak with yellow tips. The upperside of the tail passes from green at the top to blue further down, and is yellow at the tip. The underside of the tail is yellow.
Thalassomedon
"Thalassomedon" is among the largest elasmosaurids, with a total length of for the holotype. There is a larger skull however suggesting a much larger animal, potentially up to . The neck is also very long; it comprises 62 vertebrae and is about - over half of the total length. The skull is long, with long teeth. The flippers were about long. Stones have been found in its stomach area leading some to theorize that they were used for ballast or digestion. If the latter, stomach action would cause the stones to help grind ingested food.
Paraphysornis
Paraphysornis is an extinct genus of giant flightless predatory birds of the family Phorusrhacidae or "terror birds" within the subfamily Brontornithinae that lived in Brazil. Its length was about and the skull had a length of . The only known species is Paraphysornis brasiliensis.
Paramylodon
"Paramylodon" measured about 3 m (9.8 ft) in length and weighed as much as 1,000–1,089 kg. It is known from North America deposits, including in Mexico and the United States and as far south as Guatemala, and often mistaken as "Glossotherium". Currently there is just one recognized species, "P. harlani", (Owen) 1840, which is commonly referred to as Harlan's ground sloth in honor of American paleontologist Dr. Richard Harlan, who first discovered and described a lower jaw in 1835. "Paramylodon" exhibits the interesting characteristic of having had dermal ossicles, small bones embedded in the skin, presumably adding a degree of protection to the animal. This characteristic is also shared by the South American "Mylodon".
Olorotitan
"Olorotitan arharensis" is based on the most complete lambeosaurine skeleton found outside North America to date. It was a large hadrosaurid, comparable to other large lambeosaurines like "Parasaurolophus cyrtocristatus", and may have grown up to long.
Odd-toed ungulate
The largest odd-toed ungulates are rhinoceroses, and the extinct "Paraceratherium", a hornless rhino from the Oligocene, is considered one of the largest land mammals of all time. At the other extreme, an early member of the order, the prehistoric horse "Hyracotherium", had a withers height of only . Apart from dwarf varieties of the domestic horse and donkey, perissodactyls reach a body length of and a weight of . While rhinos have only sparse hair and exhibit a thick epidermis, tapirs and horses have dense, short coats. Most species are grey or brown, although zebras and young tapirs are striped.