Ben Creisler
Some recent non-dino papers:
Thiago V.V. Costa, LuÃs FÃbio Silveira, Helen F. James, SÃrgio R. Posso & Reginaldo J. Donatelli (2021)
Phylogenetic analysis of the nocturnal avian family Nyctibiidae (Caprimulgiformes) inferred from osteological characters.
Zoologischer Anzeiger (advance online publication)
doi:
https://doi.org/10.1016/j.jcz.2021.01.003 Â
https://www.sciencedirect.com/science/article/abs/pii/S0044523121000097 The family Nyctibiidae (potoos) comprises seven extant species currently included in the genera Nyctibius and Phyllaemulor, endemic to the Neotropical region, and the extinct genus Paraprefica from the Eocene of Europe. The living species are secretive nocturnal birds, characterized by spend most of the daylight time in a freezing, upright posture, resembling the top of a stump or a dead leaf. Here we present the first phylogenetic analysis of the family based on morphological characters, inferred from 37 cranial and post-cranial characters of all but one representatives of Nyctibiidae, including the extinct genus Paraprefica. TNT analysis resulted in a single most parsimonious tree with a length of 47 steps, and the ingroup topology was (Paraprefica (Phyllaemulor bracteatus (Nyctibius leucopterus (N. griseus, N. jamaicensis (N. aethereus, N. grandis))))). These results partially corroborate previous phylogenetic hypotheses based on molecular data, mainly concerning the position of P. bracteatus, but the relationships among Nyctibius species remain controversial. The osteology of this family is remarkably distinct from close related groups, especially regarding the cranial and mandibular structures, mainly due to their noteworthy habits and large eyes and mouth. The distinction between Paraprefica and Phyllaemulor + Nyctibius, allied to the geographical and temporal disjunction of these two groups, seems to be enough for their separation at the subfamily level. A notable osteological variation exists also among the Nyctibius species, albeit included in a single genus, following the high levels of genetic divergence presented in the literature, suggesting that the currently accepted systematics of the family must be reviewed.
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During the Late Triassic, metoposaurids were one of the last significant families of temnospondyl amphibians, and they have long been used in the correlation of Late Triassic tetrapod assemblages. Their fossil record extends across much of Late Triassic Pangea, including important metoposaurid fossils from the USA, Canada, Portugal, Germany, Poland, Morocco, India and Madagascar. Six genera of metoposarids are recognized: 1) Adamanian-Apachean Apachesaurus, endemic to the western USA, 2) Otischalkian Arganasaurus and Dutuitosaurus, endemic to Morocco, 3) Otischalkian-Revueltian Koskinonodon, endemic to the western USA, 4) Panthasaurus from the Otischalkian of India, and 5) Otischalkian-Adamanian Metoposaurus, known from the western USA, eastern Canada, Portugal, Italy, Germany, and Poland. Of the metoposaurid genera, only Metoposaurus has a broad enough palaeogeographic distribution and relatively restricted temporal range to be of biochronological value; its biochron identifies the OtischalkianâAdamanian (middle-late Carnian). The oldest metoposaurids are of middle Carnian age, the age of the Carnian pluvial episode of global climate. The middle Carnian broad palaeogeographic distribution, diversity and cosmopolitanism of the metoposaurids, followed by reduced diversity and relative endemism, likely indicates that climate changes were an important factor in their evolution.
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An anomalous specimen of Dinictis felina (Carnivora: Nimravidae) from the Scenic Member of the Brule Formation in South Dakota was recently identified possessing bilaterally symmetrically split carinae on the anterior surfaces of the upper canines. The anterior carinae display normal serration patterns from the apex until they bifurcate towards the base. The primary carinae maintain their normal positions while the accessory carinae diverge laterally before curving dorsally towards the tooth base. Though other types of mammalian, particularly human, tooth abnormalities are thoroughly documented, split carinae are previously unreported in mammalian taxa. However, these anomalies are well documented in disparate families of theropod dinosaurs (Tyrannosauridae, Dromaeosauridae, and Carcharodontosauridae). The aforementioned morphology of the carinae of the D. felina specimen is similar to that previously noted in theropods (e.g., split carinae on the anterior face of the tooth), suggesting a possibly homologous underlying cause. Three hypotheses for the split carinae abnormality documented in theropods were previously proposed: trauma, aberrant tooth replacement, and genetic _expression_. The continuous cycle of tooth replacement in theropods and lack of genetic information in fossil material made it difficult to confidently identify a preferred hypothesis, though genetic _expression_ was more rigorously supported. We propose that these hypotheses are not mutually exclusive, and that genetic _expression_, influenced by other factors initiating epigenetic modification, is the most parsimonious interpretation for the presence of split carinae in both mammals and theropods given the constrained pattern of mammalian tooth replacement, clear bilateral symmetry of the split carinae, and serration morphology of the accessory carinae in this specimen of D. felina.