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oai:figshare.com:article/33950845 2026-09-21T07:24:56Z category_14 category_24 category_272 category_873 category_39 category_734 category_69 portal_87 item_type_3 month_year_09_2026

A new taxon of hybodontiform (Chondrichthyes, Elasmobranchii, Hybodontiformes) from the Late Triassic of Arizona, U.S.A., and its biostratigraphic importance within the Chinle Formation Emily Keeble (8336253) Ben T. Kligman (6319655) Adam D. Marsh (5843300) Michelle R. Stocker (8920124) Sterling J. Nesbitt (7342976) Molecular Biology Evolutionary Biology Environmental Sciences not elsewhere classified Chemical Sciences not elsewhere classified Ecology Biological Sciences not elsewhere classified Inorganic Chemistry small lateral cusps productive microvertebrate site principal (= center lack ornamentation apart biostratigraphic importance within lonchidion minimorsus </ lonchidion </ biostratigraphic correlation present within localities within wide distributions upper triassic taxonomy difficult stratigraphic sequence stratigraphic gap sonsela member recognized distribution possesses teeth one population new taxon mesiodistally twice mainly relating late triassic labiolingually wide labial peg increases diversity higher levels high variation excellent candidates dockum group distinctive dentitions distal edge common occurrence chinle formation appears useful anatomical variation <p>Elasmobranchs are excellent candidates for biostratigraphy, with distinctive dentitions and wide distributions over a long period of time. However, the high variation in tooth shapes present within some groups of chondrichthyans makes disentangling species variation from higher levels of taxonomy difficult. Here, we describe a sample of over 250 isolated tooth crowns of a new taxon of hybodontiform from a productive microvertebrate site from the Sonsela Member of the Chinle Formation, Arizona, U.S.A. This sample is assigned to a new taxon, <i>Lonchidion minimorsus</i> sp. nov., which possesses teeth that are mesiodistally twice as long as they are labiolingually wide, include no or small lateral cusps, have a low to moderately defined labial peg consistent with other members of <i>Lonchidion</i>, and lack ornamentation apart from the common occurrence of two or three lingually oriented cristae. Anatomical variation is present within the sample, mainly relating to the presence and/or size of the cusplets and labial peg, number of cristae, and the angle of the distal edge of the principal (= center) cusp. Three-dimensional geometric morphometrics show variation in one population and we hope that in the future further populations or species can be compared. <i>Lonchidion minimorsus</i> sp. nov. increases diversity of the genus <i>Lonchidion</i> and fills a stratigraphic gap in the recognized distribution of chondrichthyans from the Upper Triassic of the western U.S.A. Together, the stratigraphic sequence of <i>Lonchidion</i> appears useful for biostratigraphic correlation of localities within and across the Chinle Formation and Dockum Group in the southwestern U.S.A.</p> 2026-09-21T07:24:56Z Dataset Dataset 10.6084/m9.figshare.33950845.v1 https://figshare.com/articles/dataset/A_new_taxon_of_hybodontiform_Chondrichthyes_Elasmobranchii_Hybodontiformes_from_the_Late_Triassic_of_Arizona_U_S_A_and_its_biostratigraphic_importance_within_the_Chinle_Formation/33950845 CC BY 4.0