(N) Close-up of the bone surface of one of the costal bones, exhibiting microvermiculation sculpturing pattern. (L and M) Nuchal-anterior peripheral in dorsomedial view, showing thickened and moderately to strongly upturned (arrows). (J and K) Close-up of the right anterior portion of the carapace in dorsoposterior view, showing bite marks and punctured bone. ( D and E) AMU-CURS-1098 nearly complete plastron in ventral view. ( B and C) AMU-CURS-85 nearly complete carapace in ventral view. geographicus male (front) and female (middle-left), together with the giant caimanine Purussaurus mirandai and the large catfish Phractocephalus nassi. 3, I to P) AMU-CURS-706, lower jaw (see fig. 3, E to H) AMU-CURS-233, fragment of femur ( Fig. 2, D and E) MPV-0001, nearly complete carapace and complete plastron ( Fig. 2, B and C, and 3, A to D) AMU-CURS-1098, plastron and anterior portion of carapace ( Fig. 1, A to E) AMU-CURS-85, nearly complete carapace, left humerus, and right scapula-coracoid ( Figs. New specimens described here: CIAAP-2002-01 (allotype), nearly complete carapace ( Fig. ( 17): LACM-141498, left lower jaw ramus, and Stupendemys sp. Specimens referred to as Podocnemididae ind. souzai ( 13): UFAC-1764, incomplete right humerus UFAC-1163, cervical vertebra UFAC-1294, left peripheral 1 UFAC-1544, left costal 2 UFAC-1547, right xiphiplastron UFAC-1553, cervical vertebra UFAC-1554, cervical vertebra UFAC-4370, pelvic girdle UFAC-5275, cervical vertebra UFAC-5508, anterior margin of the carapace and left hypoplastron, and LACM-131946, nuchal bone, originally attributed to Stupendemys sp. tridentata ( 8): DNPM-MCT-1496-R, nearly complete skull ( Fig. Specimens described in Wood ( 6): MCZ(P)-4376, much of the carapace, fragments of plastron, cervical 7?, both scapula-coracoids and a caudal vertebra MCNC-245, a plastron lacking the epiplastra and entoplastron, two nearly complete costals, several peripherals, and one neural MCZ(P)-4378, a right humerus. The fossil record of large-sized littoral-freshwater Podocnemididae turtles of South America also includes the skull-based Carbonemys cofrinii, and the shell-based Pelomedusoides indet., from the middle to late Paleocene of Colombia ( 12). geographicus from the late Miocene, Urumaco region ( 6, 9– 12) the skull-based Caninemys tridentata from the late Miocene, Acre region, Brazil ( 8) the controversial postcrania-based “ S.” souzai, also from the late Miocene of Acre, Brazil ( 8, 13), currently attributed as Podocnemididae incertae sedis ( 14) and the skull-based Podocnemis bassleri from the late Miocene, Acre region (Loretto), Peru ( 15). The species diversity of the giant turtles inhabiting northern South America during the Miocene is thus unclear ( 7, 8), with several forms having been proposed: the postcrania-based S. It was first described in 1976 from the Urumaco Formation in northwestern Venezuela ( 6), but our knowledge of this animal has been based on partial specimens that have resulted in a problematic taxonomy, especially due to a lack of specimens with associated skull and shell elements. One of the most iconic of these species is the gigantic turtle Stupendemys geographicus, as it is the largest nonmarine turtle ever known from a complete shell (until now rivaled only by the extinct marine turtle Archelon ischyros from the Late Cretaceous). Among them are the largest snake ( 2), caimanine crocodile ( 3), gharial ( 4), and some of the largest rodents ( 5). Since the extinction of non-avian dinosaurs, the northern Neotropics have harbored now-extinct vertebrates that have been at the extreme of large size within their respective clades ( 1). Bite marks and punctured bones indicate interactions with large caimans that also inhabited the northern Neotropics. Our findings suggest the existence of a single giant turtle species across the northern Neotropics, but with two shell morphotypes, suggestive of sexual dimorphism. The new specimens greatly increase knowledge of the biology and evolution of this iconic species. We document the largest shell reported for any extant or extinct turtle, with a carapace length of 2.40 m and estimated mass of 1.145 kg, almost 100 times the size of its closest living relative, the Amazon river turtle Peltocephalus dumerilianus, and twice that of the largest extant turtle, the marine leatherback Dermochelys coriacea. geographicus from the Miocene of Venezuela and Colombia. We describe exceptional specimens and new localities of S. Despite being among the largest turtles that ever lived, the biology and systematics of Stupendemys geographicus remain largely unknown because of scant, fragmentary finds.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |