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FIGURE 5. DMNH 2013-07-1942 in A revision of "Trinitichelys" maini (Testudinata: Baenidae) and additional material of its new genus from the Lewisville Formation (Woodbine Group, Cenomanian), Texas, USA

FIGURE 5. DMNH 2013-07-1942 vertebrae. Cervical vertebrae in A, left lateral, B, anterior, and C, posterior views. Ventral view of indeterminate dorsal vertebrae in D, with anterior to the right.

FIGURE 1 in A revision of "Trinitichelys" maini (Testudinata: Baenidae) and additional material of its new genus from the Lewisville Formation (Woodbine Group, Cenomanian), Texas, USA

FIGURE 1. Location and geologic position of the Woodbine Group. A, General stratigraphic sequence and timescale for the Cretaceous of central and north central Texas showing the position of the Woodbine Group. Terrestrial deposits represented by stippled intervals. Time scale based on Gradstein et al. (2004) and Denne et al., 2016, and modified from Noto et al. (2022). B, Map of Woodbine surface exposures in the study area showing position of localities where fossils were discovered. Exposures are stippled, water bodies are solid gray. 1 = Arlington Archosaur Site, 2 = Grapevine Lake southwest shore.

FIGURE 9 in A revision of "Trinitichelys" maini (Testudinata: Baenidae) and additional material of its new genus from the Lewisville Formation (Woodbine Group, Cenomanian), Texas, USA

FIGURE 9. Plot of Plastron Length/Carapace Length by Anterior Plastral Lobe Length/Posterior Plastral Lobe Length for baenid taxa and Glyptops, which have associated carapaces and plastra. Proportions of Gehennachelys maini comb. nov. from HMNS-10-TM. Data on other taxa from Archibald (1977, table 57), Lyson and Joyce (2009a, b), Larson et al. (2013), Sullivan et al. (2013), Lively (2015), and Lyson et al. (2019). See Table 3 for raw data. Graph generated in Microsoft Excel. Grouping abbreviations: EUB= Eubaeninae; NEU= Neurankylus spp.; PLT= Palatobaeninae/ Plesiobaena grade. Squares indicate phylogenetically ungrouped taxa (non-baenodd baenids and Glyptops), circles indicate phylogenetically grouped taxa (Neurankylus and baenodds), and red square indicates Gehennachelys maini comb. nov.

FIGURE 8 in A revision of "Trinitichelys" maini (Testudinata: Baenidae) and additional material of its new genus from the Lewisville Formation (Woodbine Group, Cenomanian), Texas, USA

FIGURE 8. Gehennachelys maini comb. nov. shell reconstruction, based on DMNH 2013-07-0696, DMNH 2013-07- 0704, DMNH 2013-07-0712, DMNH 2013-07-0784, DMNH 2013-07-1703, DMNH 2013-07-1708, DMNH 2013-07- 1942, and HMNS-10-TM. Red lines indicate estimated sulci. Abbreviations: ab= abdominal scale, an= anal scale, ce= cervical scale, eg= extragular scale, fe= femoral scale, gu= gular scale, hu= humeral scale, im= inframarginal scale; ma= marginal scale, pec= pectoral scale, pl= pleural scale, ve= vertebral scale.

FIGURE 10 in A revision of "Trinitichelys" maini (Testudinata: Baenidae) and additional material of its new genus from the Lewisville Formation (Woodbine Group, Cenomanian), Texas, USA

FIGURE 10. Gehennachelys maini comb. nov. histological thin sections: A, DMNH 2013-07-1703, an indeterminate juvenile costal, and B, DMNH 2013-07-0588, a probably fourth costal. Scale bars equal 1 mm. C, closeup of vascularized external cortex and transition to cancellous bone, with growth marks indicated by blue arrowheads, D, internal cortex with intercalated vascular rows from DMNH 2013-07-0588, and E, sutural sockets of DMNH 2013-07-1703. Abbreviations: CB= cancellous bone, ECO= external cortex, ICO= internal cortex.

FIGURE 11 in A revision of "Trinitichelys" maini (Testudinata: Baenidae) and additional material of its new genus from the Lewisville Formation (Woodbine Group, Cenomanian), Texas, USA

FIGURE 11. Results of phylogenetic analyses for Gehennachelys maini comb. nov., produced from the modified matrix Rollot et al. (2022b), with 170 minimum trees and 367 steps (CI= 0.35; RI= 0.71): A) Consensus 50% majorityrule phylogenetic tree of Baenidae; B) Strict consensus tree. Yellow stars indicate Gehennachelys maini comb. nov.

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Data from: Appearances can be deceptive: bizarre shell microanatomy and histology in a new Triassic turtle (Testudinata) from Argentina at the dawn of turtles

The origin and homology of the turtle shell are one of the most captivating topics in amniote evolution. In this contribution, we present a new species of turtle from the Late Triassic of Argentina whose peripheral plates question the homology of these bones in turtles. The external morphology of the peripheral plates of <i></i>Waluchelys cavitesta<i></i> gen. et sp. nov. (Testudinata: Australochelyidae) is as in any other turtle, however, appearances can be deceiving. Internally, these plates exhibit an unexpected internal cavity. The absence of structural similarities and of ontogenetic or phylogenetic transitional forms between the peripheral plates of W. cavitesta and other testudinatans might suggest that the periphery of turtles represents a case of deep homology. Furthermore, the present and recent findings suggest that the structure and ossification patterns of the periphery of the turtle shell were more plastic and subject to variation than other elements of the shell, at least in the earliest stages of turtle evolution. These findings also suggest that the "typical" mesochelydian turtle shell could have been acquired in a two-stage process.

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Data from: Appearances can be deceptive: bizarre shell microanatomy and histology in a new Triassic turtle (Testudinata) from Argentina at the dawn of turtles

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Data from: The early composition and evolution of the turtle shell (Reptilia, Testudinata)

The shell of the oldest true turtle (Testudinata) branch (Proterochersidae) from the Late Triassic (Norian) of Poland and Germany was built in its anterior and posterior part from an osteodermal mosaic which developed several million years after the plastron, neurals, and costal bones. The most detailed description of the shell composition in proterochersids thus far is provided together with a review of the shell composition in other Triassic pantestudinates, the scenario of early evolution of the turtle shell is proposed based on new data, and the possible adaptive meaning of the observed evolutionary changes is discussed. These observations are consistent with the trend of shell simplification previously reported in turtles. Several aspects of proterochersid shell anatomy are intermediate between O. semitestacea and more derived turtles, supporting their stem phylogenetic position. Three additional ossifications were sutured to xiphiplastra and pelvis in Proterochersis spp. and at least in some individuals the nuchal bone was paired. The peripherals, suprapygals, and pygal bone are most likely of osteodermal origin and homologous to the proterochersid shell mosaic.

opencc-zeroDec 2017View details →

FIGURE 5 in A new species of freshwater turtle of the genus Elseya (Testudinata: Pleurodira: Chelidae) from the Northern Territory of Australia

FIGURE 5. Lateral, Dorsal and Ventral views of the skull of Elseya flaviventralis. See Thomson et al. 2015; 2006 for comparative skulls of other Elseya species.

FIGURE 2 in A new species of freshwater turtle of the genus Elseya (Testudinata: Pleurodira: Chelidae) from the Northern Territory of Australia

FIGURE 2. Dorsal and lateral views of the holotype of Elseya (Elseya) flaviventralis NTM 13512, adult female from Pine Creek Crossing, South Alligator River Drainage, Kakadu National Park, Northern Territory, Australia. 13° 30' S 132° 28' E. The plastron has been disarticulated. Note the uniform coloration of the plastron, free from darker streaks and blotches, and the indistinct angle between the bridge and the plastron. Scale 10 mm.

FIGURE 1 in A new species of freshwater turtle of the genus Elseya (Testudinata: Pleurodira: Chelidae) from the Northern Territory of Australia

FIGURE 1. Adult female Yellow Bellied Snapping Turtle (Elseya (Elseya) flaviventralis) from Pul Pul Billabong, Kakadu National Park, Northern Territory (13° 34' S, 132° 35' E).

FIGURE 4 in A new species of freshwater turtle of the genus Elseya (Testudinata: Pleurodira: Chelidae) from the Northern Territory of Australia

FIGURE 4. Distribution of extant species in the genus Elseya. The ranges of Elseya rhodini and Elseya branderhorsti overlap to the west and including the Fly River drainage. Type localities are shown as red dots, with the exception of E. branderhorsti (green dot). The type locality for E. lavarackorum is outside range because it was described from a fossil from Riversleigh now outside its present range. E. rhodini occupies small streams and tributaries; E. branderhorsti occupies tidal regions, lower reaches and lakes, so the two are seldom found in microsympatry.

FIGURE 3 in A new species of freshwater turtle of the genus Elseya (Testudinata: Pleurodira: Chelidae) from the Northern Territory of Australia

FIGURE 3. Dorsal and lateral views of the Paratype (Allotype) of Elseya (Elseya) flaviventralis NTM 13985, adult male from Pul Pul Billabong, South Alligator River Drainage, Northern Territory, Australia. 13° 34' S 132° 35' E. Scale 10 mm. The plastron has been disarticulated.

Figure 16 in A new turtle from the Palaeogene of Patagonia (Argentina) sheds new light on the diversity and evolution of the bizarre clade of horned turtles (Meiolaniidae, Testudinata)

Figure 16. Gaffneylania auricularis gen. et sp. nov. Photographs of some osteoderms. A–C, asymmetric osteoderm MPEF-PV 10556 (holotype) in dorsal (A), ventral (B) and anterior (C) views. D, E, symmetric osteoderm MPEF-PV 10556 (holotype) in dorsal (D) and ventral (E) views. F, G, symmetric osteoderm MPEF-PV 10571 in dorsal (F) and ventral (G) views.

Figure 12 in A new turtle from the Palaeogene of Patagonia (Argentina) sheds new light on the diversity and evolution of the bizarre clade of horned turtles (Meiolaniidae, Testudinata)

Figure 12. Gaffneylania auricularis gen. et sp. nov., MPEF-PV 10556 (holotype). Photographs and drawings of the lower jaw in anterior (A), posterior (B), dorsal (C), ventral (D), left lateral (E) and medial (F) views.

Figure 14 in A new turtle from the Palaeogene of Patagonia (Argentina) sheds new light on the diversity and evolution of the bizarre clade of horned turtles (Meiolaniidae, Testudinata)

Figure 14. Gaffneylania auricularis gen. et sp. nov. Photographs and drawings of the axis MPEF-PV 1778-1 (A), cervical vertebra 3 MPEF-PV 10556 (holotype) (B) and a proximal caudal vertebra MPEF-PV 1778-2 (C) in anterior, left lateral, posterior, right lateral, dorsal and ventral views.

Figure 11 in A new turtle from the Palaeogene of Patagonia (Argentina) sheds new light on the diversity and evolution of the bizarre clade of horned turtles (Meiolaniidae, Testudinata)

Figure 11. Gaffneylania auricularis gen. et sp. nov., MPEF-PV 10556 (holotype). Stereophotographs and drawings of the skull in left ventroposterolateral (A) and right lateral (right quadrate removed) (B) views. Photograph and drawing of the skull in medial (C) view.

Figure 9 in A new turtle from the Palaeogene of Patagonia (Argentina) sheds new light on the diversity and evolution of the bizarre clade of horned turtles (Meiolaniidae, Testudinata)

Figure 9. Gaffneylania auricularis gen. et sp. nov., MPEF-PV 10556 (holotype). Photographs and drawing of the horn core B in anterior (A), ventral (B), lateral (C) and medial (D) views.

Figure 10 in A new turtle from the Palaeogene of Patagonia (Argentina) sheds new light on the diversity and evolution of the bizarre clade of horned turtles (Meiolaniidae, Testudinata)

Figure 10. Gaffneylania auricularis gen. et sp. nov., MPEF-PV 10556 (holotype). Photographs and drawings of the right premaxilla and maxilla in anterior (A), posterior (B) and ventral (C) views.