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Plesiochelyidae

Reptilia - Plesiochelyidae

Taxonomy

Plesiochelyidae was named by Rütimeyer (1873).

It was assigned to Pleurodira by Lydekker (1889); to Pleurodira by Hay (1902); to Amphichelydia by Delair (1958); to Pleurosternoidea by Kuhn (1966); to Chelonoidea by Gaffney (1975); to Chelonioidea by Gaffney (1975), Weems (1988) and Carroll (1988); to Cryptodira by de Broin and de la Fuente (1993); to Cryptodira by Goodwin et al. (1999); to Eucryptodira by Milner (2004), Anquetin et al. (2014), Anquetin and Chapman (2016) and Puntener et al. (2017); and to Thalassochelydia by Anquetin et al. (2017), Pérez-Garcia and Ortega (2021) and Madzia et al. (2021).

Subtaxa

Craspedochelys, Emys dutertrei, Globochelus, Hispaniachelys, Hispaniachelys prebetica, Plesiochelys (syn. Stegochelys), Portlandemys, Stylemys lindenensis, Tholemys, Yanduchelys

Synonyms

Emys dutertrei was named by Sauvage (1872). It is a 3D body fossil. Its type locality is Moulin-Wibert, which is in a Kimmeridgian marginal marine claystone in France.

It was recombined as Plesiochelys dutertrei by Sauvage (1873); it was considered a nomen dubium by Anquetin et al. (2017).
Hispaniachelys was named by Slater et al. (2011).

It was considered a nomen dubium by Pérez-García (2014).

It was assigned to Testudines by Slater et al. (2011).
Hispaniachelys prebetica was named by Slater et al. (2011). Its type specimen is RGCHSP-62-52, a carapace, and it is a 3D body fossil. Its type locality is Riogazas-Chorro Bed 62, which is in an Oxfordian/Kimmeridgian shallow subtidal limestone in the Lorente Formation of Spain.

It was considered a nomen dubium by Pérez-García (2014), Anquetin et al. (2017) and Pérez-García (2017).
Stylemys lindenensis was named by Maack (1869). Its type specimen is GZG 773-18 to GZG 773-34 (syntypes), a partial shell (a series of fragmentary and disarticulated shell elements), and it is a 3D body fossil. Its type locality is Tönjesbergs, near Hannover, which is in a Kimmeridgian marine horizon in Germany.

It was synonymized subjectively with Tropidemys seebachi by Portis (1878); it was synonymized subjectively with Plesiochelys etalloni by Bräm (1965) and Gaffney (1975); it was considered a nomen dubium by Anquetin et al. (2017).

Synonymy list

Year	Name and author
1869	Stylemys lindenensis Maack
1869	Stylemys lindensis Maack p. 320
1872	Emys dutertrei Sauvage
1873	Plesiochelyidae Rütimeyer
1873	Plesiochelys dutertrei Sauvage p. 369
1889	Plesiochelyidae Lydekker p. 183
1902	Plesiochelyidae Hay p. 439
1958	Plesiochelyidae Delair p. 51
1966	Plesiochelyidae Kuhn p. 22
1975	Plesiochelyidae Gaffney pp. 4-5
1988	Plesiochelyidae Carroll
1988	Plesiochelyidae Weems p. 141 figs. Table 2
1993	Plesiochelyidae de Broin and de la Fuente p. 13
1999	Plesiochelyidae Goodwin et al. p. 734
2004	Plesiochelyidae Milner p. 1460
2011	Hispaniachelys Slater et al.
2011	Hispaniachelys prebetica Slater et al. p. 1394 fig. 2
2014	Plesiochelyidae Anquetin et al.
2016	Plesiochelyidae Anquetin and Chapman
2017	Plesiochelyidae Anquetin et al.
2017	Plesiochelyidae Puntener et al.
2021	Plesiochelyidae Madzia et al.
2021	Plesiochelyidae Pérez-Garcia and Ortega

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Rank	Name	Author
kingdom	Animalia	()
—	Bilateria
—	Eubilateria	Ax 1987
—	Deuterostomia
phylum	Chordata	Haeckel 1874
subphylum	Vertebrata
superclass	Gnathostomata
—	Osteichthyes	()
subclass	Sarcopterygii	()
subclass	Dipnotetrapodomorpha	(Nelson 2006)
subclass	Tetrapodomorpha	()
—	Tetrapoda

Rank	Name	Author
—	Reptiliomorpha
—	Anthracosauria
subclass	Amphibiosauria	Kuhn 1967
—	Cotylosauria	()
—	Amniota
—	Sauropsida
class	Reptilia
—	Testudinata	(Oppel 1811)
—	Thalassochelydia
family	Plesiochelyidae	Rütimeyer 1873
family	Plesiochelyidae	Rütimeyer 1873

If no rank is listed, the taxon is considered an unranked clade in modern classifications. Ranks may be repeated or presented in the wrong order because authors working on different parts of the classification may disagree about how to rank taxa.

Fm. †Plesiochelyidae Rütimeyer 1873

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G. †Craspedochelys Rütimeyer 1873

†Craspedochelys jaccardi Pictet 1860

Invalid names: Plesiochelys choffati Sauvage 1898 [synonym]

†Craspedochelys passmorei Andrews 1921

†Craspedochelys picteti Rütimeyer 1873

Invalid names: Craspedochelys crassa Rütimeyer 1873 [synonym]

Invalid names: Emys dollfusii Lennier 1870 [nomen dubium]

G. †Globochelus de Lapparent de Broin et al. 2021

†Globochelus lennieri de Lapparent de Broin et al. 2021

G. †Plesiochelys Rütimeyer 1873

†Plesiochelys bigleri Puntener et al. 2017

†Plesiochelys etalloni Pictet and Humbert 1857

Invalid names: Plesiochelys langii Rütimeyer 1873 [synonym], Plesiochelys sanctaeverenae Rütimeyer 1873 [synonym], Plesiochelys solodurensis Rütimeyer 1873 [synonym], Stylemys hannoverana Maack 1869 [synonym]

†Plesiochelys kwanganensis Yeh 1963

†Plesiochelys normandicus Bergounioux 1937

†Plesiochelys oshanensis Yeh 1973

†Plesiochelys planiceps Owen 1842

Invalid names: Clemmys grayi Fitzinger 1835 [nomen oblitum], Emys hugi Gray 1831 [nomen oblitum], Emys hugii Gray 1831 [nomen oblitum], Emys jurensis Keferstein 1834 [nomen oblitum], Emys trionychoides Gray 1831 [nomen oblitum], Plesiochelys minor Portis 1878 [nomen dubium], Stegochelys Lydekker 1889 [synonym]

G. †Portlandemys Gaffney 1975

†Portlandemys gracilis Anquetin et al. 2015

†Portlandemys mcdowelli Gaffney 1975

G. †Tholemys Andrews 1921

G. †Yanduchelys Peng et al. 2005

†Yanduchelys delicatus Peng et al. 2005

Invalid names: Emys dutertrei Sauvage 1872 [nomen dubium], Hispaniachelys Slater et al. 2011 [nomen dubium], Hispaniachelys prebetica Slater et al. 2011 [nomen dubium], Stylemys lindenensis Maack 1869 [nomen dubium]

Diagnosis

Reference	Diagnosis
E. S. Gaffney 1975	Skull roof: Temporal emargination better developed than in most Chelonioidea except Desmatochelys and Corsochelys; parietal, quadratojugal, and squamosal exposed along temporal margin, parietal-squamosal suture absent. Frontal entering orbital margin. Maxilla and quadratojugal not in contact. Parietals small in contrast to Recent Cheloniidae. Postorbital about intermediate in size between Toxochelys and Recent Cheloniidae. Cheek emargination more extensive than in other Chelonioidea. Jugal relatively small in contrast to living Cheloniidae. Nasals present. Prefrontals meeting in midline. Prefrontal-frontal suture transverse. Palate: Primary palate present. High labial ridge and strong lingual ridge directly bordering apertura narium interna. Ventral margin of labial ridge convex in lateral view. Processus pterygoideus externus developed as in most Testudinoidea and not reduced as in Cheloniidae. Foramen palatinum posterius present (but open posterolaterally in Plesiochelys). Foramen praepalatinum present. Vomer completely separating palatines in ventral view but lacking lateral expansion seen in most cryptodires. Basisphenoid and basioccipital of equal width in ventral view. Prominent transverse ridge on posterior surface of processus articularis of quadrate with trough on ventral side. Braincase: Trabeculae of rostrum basisphenoidale not fused or closely apposed. Sella turcica somewhat reduced in comparison with Chelydra but not so reduced as in most other Chelonioidea. Paired foramina anterius canalis carotici interni not lying close together as in Toxochelys or Cheloniidae but not placed far laterally as in Chelydra and most Testudinoidea. Dorsum sellae high and separated from sella turcica and foramina anterius canalis carotici interni by prominent bone surface having sagittal ridge. Posterior portion of sella turcica not concealed by overhanging dorsum sellae. Canalis caroticus internus not entering sulcus cavernosus as in Recent Cheloniidae. Processus inferior parietalis reduced in anteroposterior extent in comparison to Chelydra and Testudinoidea but not so reduced as in Recent Cheloniidae. Foramen nervi trigemini relatively smaller in Chelydra and conspicuously smaller than in Recent Cheloniidae. Processus trochlearis oticum moderately well developed, as in Chelydra. Parietal extending ventrally to meetpterygoid along posterior margin of foramen nervi trigemini, as in many batagurine testudinids. Epipterygoid large and broadly entering margin of foramen interorbitale; entering or not margin of foramen nervi trigemini. Anterior opening of foramen nervi abducentis posteroventral to base of processus clinoideus in contrast to Recent Cheloniidae and most turtles. Lower Jaw: Triturating surface narrow in contrast to Recent Cheloniidae. High labial and subequal or lower (but distinct) lingual ridge; well developed trough between labial and lingual ridges for reception of lingual ridge of skull; no accessory ridges present. Symphyseal hook present or absent. Processus coronoideus higher than in Recent Cheloniidae. Surangular exposed posteriorly in contrast to Chelydra but not so exposed as in Caretta. Surangular bearing variable portion of area articularis mandibularis as in Recent Cheloniidae. Splenial present and large in contrast to nearly all other cryptodires. Fossa meckelii and most of sulcus (canalis) cartilaginis meckelii closed medially by splenial and prearticular.
J. Anquetin et al. 2017	“Plesiochelyids” are primarily differentiated from all other thalassochelydians by the presence of a high dorsum sellae that does not overhang the sellae turcica, the placement of the foramina anterius canalis carotici cerebralis more anterior than the level of the dorsum sellae, the exclusion of the epipterygoid from the anterior margin of the foramen nervi trigemini (also in Juras-ichelon oleronensis), a relatively large size (carapace length 400 to 550 mm), the lack of carapacial fontanelles in adults, an osseous bridge, and, at most, a central plastral fontanelle.