Allaeochelys crassesculpta

Le résumé fourni par la source

Allaeochelys crassesculpta (Harrassowitz, 1922) = Anosteira gracilis Harrassowitz, 1922. (for the full taxonomic history, see Joyce (2014)) Type material. • HLMD 4353 (specimen no. 3 of Harrassowitz (1922)), syntype, a poorly-preserved shell (Harrassowitz 1922, pl. 2.2; Suppl. material 1: fig. S 1.4); • HLMD 4283 (specimen no. 4 of Harrassowitz (1922)), syntype, hyoplastra, hypoplastra and xiphiplastra (Harrassowitz 1922, pl. 6.4; Suppl. material 1: fig. S 1.3); • HLMD 1461 (specimen no. 6 of Harrassowitz (1922)), syntype, nearly complete skeleton embedded in a concretion (Harrassowitz (1922), pl. 6.1; Fig. 14). Referred material. This list comprises all specimens from Messel Pit that are, to our knowledge, available in public collections and that can be undoubtedly referred to Allaeochelys crassesculpta, but we suspect there are many more. For figures, please consult Table 1 and Suppl. material 1. BSPG 1982 I 74, a nearly complete skeleton; FHM 45, a nearly complete skeleton; FHM 46, a nearly complete juvenile skeleton; HLMD Be 158, a nearly complete skeleton; HLMD Be 159, a nearly complete skeleton; HLMD Be 169, a juvenile skeleton; HLMD Be 217, a crushed and folded skeleton; HLMD Be 235, a nearly complete skeleton; HLMD Me 3173, a partial skeleton; HLMD Me 3377, a fragmentary skeleton; HLMD Me 4000, a partial carapace (syntype of Allaeochelys gracilis, specimen no. 5 of Harrassowitz (1922)); HLMD Me 4282 (syntype of Allaeochelys gracilis, specimen no. 1 of Harrassowitz (1922)), a nearly complete skeleton (Harrassowitz 1922; pl. 1.3, pl. 4.2, pl. 4.4, pl. 6.5, pl. 6.6); HLMD Me 5001, a partial carapace; HLMD Me 7427, a nearly complete, but folded shell; HLMD Me 7428, posterior half of carapace; HLMD Me 7429, a nearly complete carapace; HLMD Me 7592, a nearly complete skeleton; HLMD Me 7593, a nearly complete pair of skeletons; HLMD Me 7599, a partial skeleton; HLMD Me 7892, a partial skeleton; HLMD Me 9722, a nearly complete skeleton; HLMD Me 9795, a nearly complete skeleton; HLMD Me 10375, a partial skeleton; HLMD Me 13397, a fragmentary skeleton; HLMD Me 13432, a costal; HLMD Me 13436, a nearly complete skeleton; HLMD Me 13484, a nearly complete skeleton; HLMD Me 13721, a nearly complete skeleton; HLMD Me 14919, a nearly complete, folded skeleton; HLMD Me 14920, a nearly complete skeleton; HLMD Me 14997, a nearly complete skeleton; HLMD Me 14998, a nearly complete skeleton; HLMD Me 14999, a nearly complete skeleton; HLMD Me 15012, a nearly complete skeleton; HLMD Me 15273, a partial skeleton; HLMD Me 15372, a nearly complete skeleton; HLMD Me 15563, a partial skeleton; HLMD Me 15660, a fragmentary skeleton; HLMD Me 15956, a nearly complete skeleton; HLMD Me 42827, a nearly complete skeleton; IRSNB MeR 001, a nearly complete skeleton; IRSNB MeR 002, a nearly complete skeleton; IRSNB MeR 006, a nearly complete skeleton; IRSNB MeR 007, a juvenile skeleton; IRSNB MeR 010, a nearly complete pair of skeletons; IRSNB MeR 011, a nearly complete skeleton; IRSNB MeR 012, a nearly complete, but crushed cranium; IRSNB MeR 014, a nearly complete skeleton; IRSNB MeR 015, a juvenile skeleton; IRSNB MeR 018, a nearly complete skeleton; IRSNB MeR 020, a nearly complete skeleton; IRSNB MeR 022, a nearly complete skeleton; IRSNB MeR 024, a nearly complete skeleton; IRSNB MeR 025, a juvenile skeleton; IRSNB MeR 029, a nearly complete skeleton; IRSNB MeR 030, a nearly complete skeleton; IRSNB MeR 031, a nearly complete skeleton; IRSNB MeR 032, a nearly complete skeleton; IRSNB MeR 034, a nearly complete skeleton; SMF Me 373, a nearly complete skeleton; SMF Me 436, a partial skeleton; SMF Me 441, a partial skeleton; SMF Me 514, a nearly complete skeleton; SMF Me 611, a nearly complete skeleton; SMF Me 718, a partial shell; SMF Me 938, partial posterior part of carapace; SMF Me 1444, a nearly complete skeleton; SMF Me 1794, a complete shell; SMF Me 1808, a partial skeleton; SMF Me 1809, a nearly complete skeleton; SMF Me 2009, a partial skeleton; SMF Me 2010, a partial skeleton; SMF Me 2034, a partial pair of skeletons; SMF Me 2449, a nearly complete skeleton; SMF Me 2606, a partial skeleton; SMF Me 3004, an isolated and crushed cranium; SMF Me 3018, a nearly complete skeleton; SMF Me 3566, a nearly complete pair of skeletons; SMF Me 3775, a partial skeleton; SMF Me 3779, a partial skeleton; SMF Me 3783, a partial skeleton; SMF Me 3787, a partial skeleton; SMF Me 11381, a juvenile skeleton; SMF Me 11418, a partial skeleton; SMF Me 11573, a partial skeleton; SMNK Pal 986, a nearly complete skeleton; SMNK Pal 45053, a fragmentary skeleton. Type locality and horizon. Messel Pit, near the village of Messel, State of Hesse, Germany (Harrassowitz 1922: fig. 6); MP 11, early Lutetian (ca. 47 Ma), middle Eocene (Joyce et al. 2012). Amended diagnosis. Allaeochelys crassesculpta can be diagnosed as a representative of Carettochelyidae by a bone surface ornamentation consisting of thick ridges separated by equally-sized grooves, presence of a quadrate fossa, presence of a midline keel on the dorsal surface of the carapace, a single suprapygal, presence of a lip formed on the visceral side of the posterior peripherals and pygal, plastral kinesis, a triangular entoplastron, and reduction of plastral scutes. Allaeochelys crassesculpta can be diagnosed as a member of Carettochelyinae by the presence of a maxilla-quadratojugal contact below the jugal, absence of a contact between the quadratojugal and squamosal, presence of elongate tubercula basioccipitale, complete loss of carapace and plastral scutes, and an equilateral entoplastron. Allaeochelys crassesculpta can be differentiated from other carettochelyines by having a straight labial margin of the maxilla, an anteroposteriorly short postorbital, a moderately deep quadrate fossa, a large antrum postoticum, a foramen posterius canalis carotici interni located close to the parabasisphenoid-pterygoid suture at about mid-length of the parabasisphenoid, a pterygoid fossa ventrally open and not covered by an enfolded ridge of the pterygoid, a supraoccipital excluded from the skull roof, and a flat ventral surface of the basioccipital. Description. Cranium General comments. SMF Me 3004 is a crushed, flattened cranium (Fig. 1). After segmentation and reconstruction, it appears that none of the bones is completely preserved. All reconstructed bones are incomplete. The prefrontals, frontals, premaxilla, maxillae, jugals, quadrates, and parabasisphenoid are fairly well-preserved, whereas the vomer, pterygoids, and opisthotics are highly incomplete (Fig. 2). As the cranium is heavily compressed dorsoventrally, the secondary wall of the braincase is the area that suffered most. In the µCT dataset, we were not able to identify any pieces in that area as belonging to either bone forming the secondary braincase wall of other carettochelyids and most of the material that can visually be attributed to bone and not matrix was either too crushed or too small to be identified with confidence. These fragments were, thus, omitted from the segmentations and reconstructions. Consequently, most anatomical structures located in that area, such as the foramen nervi trigemini or cavum labyrinthicum, are either incomplete or missing completely. Likewise, the epipterygoids, which were likely present by reference to other pan-trionychians, could not be segmented and described as they were completely crushed and destroyed. SMF Me 3004 preserves the typical surface ornamentation of carettochelyids, which is made of thick ridges separated by equally-sized grooves that are mostly visible on the prefrontals, frontals, and parietals (Figs 2, 3). The surface ornamentation of the cranium, however, is less pronounced than on the shell. As in all carettochelyids (Waite 1905; Walther 1922; Havlik et al. 2014; Joyce 2014; Danilov et al. 2017 a; Joyce et al. 2018; White et al. 2023; Rollot et al. 2024 a, 2024 b, 2025), the cranium has a deep upper temporal emargination, a

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.