Devonian Biostratigraphy of Mongolia (Nauka, 1993). Brachiopods and Biostratigraphy of the Lower Devonian of Mongolia (Nauka, 1981).Īlekseeva, R. Grundriss der vergleichenden Anatomie (Wilhelm Engelmann, 1874).Īlekseeva, R. Observations to the note by E Vorobjeva: ‘First discovery of Palaeozoic fishes on the territory of the Mongolian Republic’. The systematics of the Mongolepidida (Chondrichthyes) and the Ordovician origins of the clade. Mongolepis-a new lower Silurian genus of elasmobranchs from Mongolia.

Teslepis-a new representative of mongolepid elasmobranchs from the Lower Silurian of Mongolia. Sodolepis-a new representative of Mongolepidida (Chondrichthyes?) from the lower Silurian of Mongolia. Histology of the galeaspid dermoskeleton and endoskeleton, and the origin and early evolution of the vertebrate cranial endoskeleton. Architectural and ultrastructural features of tessellated calcified cartilage in modern and extinct chondrichthyan fishes. A reappraisal of the origin and basal radiation of the Osteichthyes. The relationships of the palaeoniscid fishes, a review based on new specimens of Mimia and Moythomasia from Upper Devonian of Western Australia. Lungfishes, tetrapods, paleontology, and plesiomorphy. Early evolution of vertebrate skeletal tissues and cellular interactions, and the canalization of skeletal development. Furthermore, they revive theories of a phylogenetically deeper origin of endochondral bone and its absence in chondrichthyans as a secondary condition. These results provide direct support for theories of generalized bone loss in chondrichthyans. Phylogenetic analyses place this new taxon as a proximate sister group of the gnathostome crown. However, its endochondral space is filled with an extensive network of fine trabeculae resembling the endochondral bone of osteichthyans. The fossil consists of a partial skull roof and braincase with anatomical details providing strong evidence of placement in the gnathostome stem group. Here we report the discovery of extensive endochondral bone in Minjinia turgenensis, a new genus and species of ‘placoderm’-like fish from the Early Devonian (Pragian) of western Mongolia described using X-ray computed microtomography. The absence of bone in modern jawless fishes and the absence of endochondral ossification in early fossil gnathostomes appear to lend support to this conclusion. Chondrichthyans (sharks and their kin) are the living sister group of osteichthyans and have primarily cartilaginous endoskeletons, long considered the ancestral condition for all jawed vertebrates (gnathostomes).

Endochondral bone is the main internal skeletal tissue of nearly all osteichthyans-the group comprising more than 60,000 living species of bony fishes and tetrapods.

Bomes with martin mpc