Microvertebrates Paleontology

The Rhaetian (latest Triassic) is best known for its basal bone bed, but there are numerous other bone- rich horizons in the succession. Boreholes taken around the M4–M5 motorway junction in SW England provide measured sections with multiple Rhaetian bone beds. The microvertebrate samples in the various bone beds differ through time in their composition and in average specimen size. The onset of the Rhaetian transgression accumulated organic debris to form a fossiliferous layer high in biodiversity at the base of the Westbury Formation. The bone bed at the top of the Westbury Formation represents a community with lower biodiversity. The bone beds differ in their faunas: chondrichthyan teeth are dominant in the basal bone bed, but actinopterygians dominate the higher bone bed. These differences
could be taphonomic, but are more likely evidence for ecological-evolutionary changes. Further, a change from larger to smaller specimen sizes up-sequence allows rejection of an earlier idea that the
successive bone beds represented multiple reworkings of older bone beds.

Se denuncia a Ulyses Pardiñas como perpetrador de varios tipos de fraudes científicos realizados en su tesis doctoral y en varios artículos respecto de la fauna, estratigrafía y cronología de Cueva Tixi. En este artículo se describen las pruebas de esos fraudes.

The Moncure microvertebrate locality in the Cumnock Formation, Sanford sub-basin, North Carolina, dramatically increases the known Late Triassic age vertebrate assemblage from the Deep River Basin. The ,50,000 recovered microvertebrate fossils include osteichthyans, amphibians, and numerous lepidosauromorph, archosauriform, and synapsid amniotes. Actinopterygian fossils consist of thousands of scales, teeth, skull, and lower jaw fragments, principally of redfieldiids and semionotids. Non-tetrapod sarcopterygians include the dipnoan Arganodus sp., the first record of lungfish in the Newark Supergroup. Temnospondyls are comparatively rare but the preserved centra, teeth, and skull fragments probably represent small (juvenile) metoposaurids. Two fragmentary teeth are assigned to the unusual reptile Colognathus obscurus (Case). Poorly preserved but intriguing records include
acrodont and pleurodont jaw fragments tentatively assigned to lepidosaurs. Among the archosauriform teeth is a taxon distinct from R. callenderi that we assign to Revueltosaurus olseni new combination, a morphotype best assigned to cf. Galtonia, the first Newark Supergroup record of Crosbysaurus sp., and several other archosauriform tooth morphotypes, as well as grooved teeth assigned to the recently named species Uatchitodon schneideri. Synapsids represented by molariform teeth include both ‘‘traversodontids’’ assigned to aff. Boreogomphodon and the ‘‘dromatheriid’’ Microconodon. These records are biogeographically important, with many new records for the Cumnock Formation and/or the Newark Supergroup. In particular, Colognathus, Crosbysaurus, and Uatchitodon are known from basins of Adamanian age in the southwestern U.S.A. These new records include microvertebrate
taxa more typical of non-Newark basins (abundant archosauriforms, temnospondyls, lungfish) as well as more
typical Newark osteichthyans and synapsid-rich faunal elements.