Extinct family of turtles
Compsemydidae is an extinct family of turtles, likely belonging to the clade Paracryptodira. The earliest undisputed member is "Tongemys" from the Berriasian age of the Early Cretaceous; two Late Jurassic genera ("Riodevemys" and "Selenemys") have also sometimes been included in the group, but may alternatively be members of the family Pleurosternidae. The genus "Compsemys" survived the Cretaceous–Paleogene extinction event and lasted until the Thanetian age of the Paleocene.
Taxonomy.
Compsemydidae was named in a 2015 paper by Pérez-García "et al.", who included the type genus "Compsemys" and its possible synonym "Berruchelus". A 2020 paper by Joyce and Rollot expanded the family to include the enigmatic "Peltochelys" from the Early Cretaceous, as well as the Late Jurassic "Riodevemys" and "Selenemys" that had earlier been placed in Pleurosternidae. A 2021 paper by Rollot "et al." added the Late Cretaceous "Kallokibotion" to the family, but moved "Riodevemys" back into Pleurosternidae. 2022 saw the description of two new compsemydids, the Early Cretaceous "Tongemys" and the Late Cretaceous "Calissounemys", by Joyce "et al." and Tong "et al." respectively.
Joyce &amp; Rollot (2020) defined Compsemyidae as "the most inclusive group of turtles that includes "Compsemys victa" but not the baenid "Baena arenosa" Leidy, 1870, the pleurosternid "Pleurosternon bullockii" (Owen, 1842), or any extant turtle".
Phylogeny.
A phylogenetic analysis by Pérez-García "et al." (2015) found Compsemydidae to be the most basal (early-diverging) group within Paracryptodira, lying outside Baenoidea, the clade formed by Baenidae and Pleurosternidae. Rollot "et al." (2021) instead found Compsemydidae to be more closely related to traditional baenids than to pleurosternids, thus making Compsemydidae a subgroup of Baenidae by definition. Rollot &amp; Joyce (2022) recovered compsemydids as early-diverging paracryptodires when using implied weighting, but the group was placed in a polytomy with Paracryptodira and several other turtle genera when equal weighting was used.
The cladogram below follows the implied weighting analysis of Rollot &amp; Joyce (2022), with the rogue taxa "Pleurosternon moncayensis" and "Scabremys ornata" removed:
References.
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