resembles that of a sponge. Behavior contracts abruptly expelling water, giving them the name "sea squirts." Body 5 PHYLUM CHORDATA SUBPHYLUM CEPHALOCHORDATA chordates. Lancelets, Amphioxus, Branchiostoma. Small marine animals with Primitive fish-like bodies and notochord. range: Cambrian to Holocene. Geologic of life: Bottom dwellers. Lancelets spend much of their time burrowing in the sand in Mode warm, coastal, marine environments. Filter feeders. Relatively sessile but capable of swimming. An ancestor to the vertebrates resembled a lancelet-like creature (Pikaia). Significance: 6 Chief characteristics: resemble a small, colorless anchovy fillet. Lancelets obvious eyes or lateral fins. No Worm-like. segmented axial muscles, gill slits, a dorsal hollow nerve cord, a notochord, and a Has post-anal tail. solid skeleton. Nothing resembling a vertebral column. No PHYLUM CHORDATA SUBPHYLUM CEPHALOCHORDATA 7 FIGURE 12-60 Branchiostoma, a fishlike member of the subphylum Cephalochordata. WHAT ARE CONODONTS? conodonts were previously placed in a separate phylum (Phylum Conodonta), because The their affinities were unknown. current interpretation places the conodont-bearing animal with the Chordates in The Phylum Chordata. organism from which they came is not known with certainty. The Examples of various shapes of conodont elements. Photographs courtesy of K. Chauff 8 CONODONTS characteristics: in size Microscopic of calcium fluorapatite. Composed - cone-shaped teeth, or bars with rows of tooth-like denticles, or irregular knobby Shape plates called platforms. conodont element is part of a larger organism. Most fossil occurrences are of Each disassociated elements, but occasionally they are found arranged in specific assemblages or “apparatuses." 9 CONODONTS Conodont means "cone" + "teeth" (dont) Name: Neoproterozoic to Late Triassic. Geologic of life: Marine, free-swimming. Mode 10 CONODONTS Significance: in biostratigraphy Useful
Behavior resembles that of a sponge. Body contracts abruptly expelling water, giving them the name "sea squirts." 5 PHYLUM CHORDATA SUBPHYLUM CEPHALOCHORDATA Primitive chordates. Lancelets, Amphioxus, Branchiostoma. Small marine animals with fish-like bodies and notochord. Geologic range: Cambrian to Holocene. Mode of life: Bottom dwellers. Lancelets spend much of their time burrowing in the sand in warm, coastal, marine environments. Filter feeders. Relatively sessile but capable of swimming. Significance: An ancestor to the vertebrates resembled a lancelet-like creature (Pikaia). 6 Chief characteristics: Lancelets resemble a small, colorless anchovy fillet. No obvious eyes or lateral fins. Worm-like. Has segmented axial muscles, gill slits, a dorsal hollow nerve cord, a notochord, and a post-anal tail. No solid skeleton. Nothing resembling a vertebral column. PHYLUM CHORDATA SUBPHYLUM CEPHALOCHORDATA 7 FIGURE 12-60 Branchiostoma, a fishlike member of the subphylum Cephalochordata. WHAT ARE CONODONTS? The conodonts were previously placed in a separate phylum (Phylum Conodonta), because their affinities were unknown. The current interpretation places the conodont-bearing animal with the Chordates in Phylum Chordata. The organism from which they came is not known with certainty. Examples of various shapes of conodont elements. Photographs courtesy of K. Chauff 8 CONODONTS characteristics: Microscopic in size Composed of calcium fluorapatite. Shape - cone-shaped teeth, or bars with rows of tooth-like denticles, or irregular knobby plates called platforms. Each conodont element is part of a larger organism. Most fossil occurrences are of disassociated elements, but occasionally they are found arranged in specific assemblages or “apparatuses." 9 CONODONTS Name: Conodont means "cone" + "teeth" (dont) Geologic Neoproterozoic to Late Triassic. Mode of life: Marine, free-swimming. 10 CONODONTS Significance: Useful in biostratigraphy
Ch12%20Life%20of%20the%20Paleozoic%20Notes.docx