Not Triassic but too potentially cool to pass up....
O'Keefe, F. R., and L. M. Chiappe. 2011. Viviparity and K-Selected Life History in a Mesozoic Marine Plesiosaur (Reptilia, Sauropterygia). Science 333:870-873. DOI: 10.1126/science.1205689
Abstract - Viviparity is known in several clades of Mesozoic aquatic reptiles, but evidence for it is lacking in the Plesiosauria. Here, we report a Late Cretaceous plesiosaur fossil consisting of a fetus preserved within an adult of the same taxon. We interpret this occurrence as a gravid female and unborn young and hence as definitive evidence for plesiosaur viviparity. Quantitative analysis indicates that plesiosaurs gave birth to large, probably single progeny. The combination of viviparity, large offspring size, and small brood number differs markedly from the pattern seen in other marine reptiles but does resemble the K-selected strategy of all extant marine mammals and a few extant lizards. Plesiosaurs may have shared other life history traits with these clades, such as sociality and maternal care.
Showing posts with label Cretaceous. Show all posts
Showing posts with label Cretaceous. Show all posts
Albinykus baatar, a New Small Alverezsaurid From the Late Cretaceous of Mongolia
I know it's not Triassic, but I have to give props to my friends, colleague, and two of my grad school advisors!
Nesbitt, S. J., Clarke, J. A., Turner, A. H., and M. A. Norell. 2011. A small alvarezsaurid from the eastern Gobi Desert offers insight into evolutionary patterns in the Alvarezsauroidea. Journal of Vertebrate Paleontology 31:144-153. DOI: 10.1080/02724634.2011.540053
Abstract - A partial postcranial skeleton of a small alvarezsaurid from the Late Cretaceous of the Mongolian eastern Gobi Desert locality of Khugenetslavkant represents the first reported articulated theropod material from that locality. The specimen is recognized as the holotype of a new taxon herein named Albinykus baatar, gen. et sp. nov. Phylogenetic analysis places Albinykus within Alvarezsauridae as the sister taxon of Shuvuuia, another Late Cretaceous Mongolian taxon from the slightly younger Djadokhta Formation. The complete coossification of the proximal tarsals with the tibia, and of the distal tarsals and proximal metatarsals, present in Albinykus are previously unknown in Alvarezsauridae. Extensive fusion is consistent with histological data from the tibia indicating that the individual was a subadult. These results are striking given that Albinykus is among the smallest known non-avian dinosaurs with a body mass no greater than 1 kg and ranks among the smallest known alvarezsaurids. Alvarezsauridae shows a decreasing size trend throughout its evolutionary history, a rarity among dinosaurian clades. Within maniraptoran dinosaurs, such a trend has thus far only been recognized within Avialae and at the origin of Paraves with respect to other coelurosaurs. The holotype was recovered articulated in a 'seated' position, with hind limbs aligned and the feet tucked under the body. This body posture, which is present in Aves, has been previously noted in other maniraptoran clades (i.e., Oviraptoridae Troodontidae) and is now recognized in Alvarezsauridae.
Nesbitt, S. J., Clarke, J. A., Turner, A. H., and M. A. Norell. 2011. A small alvarezsaurid from the eastern Gobi Desert offers insight into evolutionary patterns in the Alvarezsauroidea. Journal of Vertebrate Paleontology 31:144-153. DOI: 10.1080/02724634.2011.540053
Abstract - A partial postcranial skeleton of a small alvarezsaurid from the Late Cretaceous of the Mongolian eastern Gobi Desert locality of Khugenetslavkant represents the first reported articulated theropod material from that locality. The specimen is recognized as the holotype of a new taxon herein named Albinykus baatar, gen. et sp. nov. Phylogenetic analysis places Albinykus within Alvarezsauridae as the sister taxon of Shuvuuia, another Late Cretaceous Mongolian taxon from the slightly younger Djadokhta Formation. The complete coossification of the proximal tarsals with the tibia, and of the distal tarsals and proximal metatarsals, present in Albinykus are previously unknown in Alvarezsauridae. Extensive fusion is consistent with histological data from the tibia indicating that the individual was a subadult. These results are striking given that Albinykus is among the smallest known non-avian dinosaurs with a body mass no greater than 1 kg and ranks among the smallest known alvarezsaurids. Alvarezsauridae shows a decreasing size trend throughout its evolutionary history, a rarity among dinosaurian clades. Within maniraptoran dinosaurs, such a trend has thus far only been recognized within Avialae and at the origin of Paraves with respect to other coelurosaurs. The holotype was recovered articulated in a 'seated' position, with hind limbs aligned and the feet tucked under the body. This body posture, which is present in Aves, has been previously noted in other maniraptoran clades (i.e., Oviraptoridae Troodontidae) and is now recognized in Alvarezsauridae.
Subscribe to:
Posts (Atom)