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3D models of: The ecomorphology of the shell of extant turtles and its applications for fossil turtles Project ID: 0000C1038 Public
70 Media · 70 Specimens · Managed by: Ilya Dziomber Turtles are a successful clade of reptiles that originated in the Late Triassic. The group adapted during its evolution to different types of environments, ranging from dry land to ponds, rivers, and the open ocean, and survived all Mesozoic and Cenozoic extinction events. The body of turtles is characterized by a shell, which has been hypothesized to have several biological roles, like protection, thermal and pH regulation, but also to be adapted in its shape to the ecology of the animal. However, only few studies have investigated the relationships between shell shape and ecology in a global context or clarified if shape can be used to diagnose habitat preferences in fossil representatives. Here, we assembled a three-dimensional dataset of 69 extant turtles and 3 fossils, in particular, the Late Triassic Proganochelys quenstedtii and Proterochersis robusta and the Late Jurassic Plesiochelys bigleri to test explicitly for a relationship between shell shape and ecology. 3D models were obtained using surface scanning and photogrammetry. The general shape of the shells was captured using geometric morphometrics. The habitat ecology of extant turtles was classified using the webbing of their forelimbs as a proxy. Principal component analysis (PCA) highlights much overlap between habitat groups. Discriminant analyses suggests significant differences between extant terrestrial turtles, extant fully aquatic (i.e., marine and riverine) turtles, and an unspecialized assemblage that includes extant turtles from all habitats, mostly freshwater aquatic forms. The paleoecology of the three fossil species cannot be determined with confidence, as all three fall within the unspecialized category, although Plesiochelys bigleri plots closer to fully aquatic turtles, while the two Triassic species group closer to extant terrestrial forms. Although the shape of the shell of turtles indeed contains an ecological signal, it is overall too weak to uncover using shell shape in paleoecological studies, at least with the methods we selected.

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  ID Part Object Taxonomy Type Date Added Publication Status  
000116443 nmb:14 Macrochelys temminckii Mesh 2020-05-21 Restricted Download  
000116444 nmb:5763 Eretmochelys imbricata Mesh 2020-05-21 Restricted Download  
000116567 nmb:152 Chelonia mydas Mesh 2020-05-23 Restricted Download  
000116445 mhnf:11858_1993 Caretta caretta Mesh 2020-05-21 Restricted Download  
000116494 smns:16980 Proganochelys quenstedtii Mesh 2020-05-21 Restricted Download  
000116495 smns:17561 Proterochersis robusta Mesh 2020-05-21 Restricted Download  
000116493 fmnh:amphibians and reptiles:73919 Lissemys punctata Mesh 2020-05-21 Restricted Download  
000116490 fmnh:amphibians and reptiles:24249 Pelodiscus sinensis Mesh 2020-05-21 Restricted Download  
000116492 fmnh:amphibians and reptiles:7845 Apalone mutica Mesh 2020-05-21 Restricted Download  
000116491 fmnh:amphibians and reptiles:19492 Rafetus euphraticus Mesh 2020-05-21 Restricted Download  
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