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[dinosaur] Adzebill evolution + baurusuchid osteoderms + Diprosopovenator (shark) + more non-dino

Ben Creisler

Some recent non-dino papers:

Grace M. Musser & Joel Cracraft (2019)
A New Morphological Dataset Reveals a Novel Relationship for the Adzebills of New Zealand (Aptornis) and Provides a Foundation for Total Evidence Neoavian Phylogenetics.
American Museum Novitates 3927: 1-70Â

Should be posted in open access at this AMNH link in the near future:

Relationships among Neoaves, a group comprising approximately 95% of all extant birds, are difficult to resolve because of multiple short internodes presumably created by a rapid evolutionary radiation around the K/Pg boundary. This difficulty has plagued both morphological and molecular studies. Compared with molecular studies with extensive taxon and character sampling, morphological datasets have largely failed to provide insight into the phenotypic evolutionary transitions of the neoavian radiation. Extinct neoavian taxa remain an understudied but critical key to resolving relationships among these problematic stem lineages and understanding evolutionary changes in structure and function. Adzebills (Aptornis), some of the most phylogenetically controversial fossil neoavians, are extinct terrestrial birds endemic to New Zealand since at least the early Miocene. Past morphological studies have placed adzebills as a sister taxon to the flightless Kagu of New Caledonia (Rhynochetos jubatus) or to the land- and waterfowl group Galloanseres. Recent molecular studies reveal the Kagu and Sunbittern (Eurypyga helias) to be sister taxa, whereas adzebills have been postulated to be within Rallidae (rails, gallinules, and coots) or the sister taxon of Sarothruridae (flufftails) or Ralloidea (finfoots, flufftails, and rails). To better resolve the position of adzebills and begin constructing a fine-scale total evidence phylogenetic dataset for the base of Neoaves, we constructed a new and more comprehensive morphological dataset of 368 discrete osteological characters for 38 extant and two extinct taxa that includes extensive sampling of nearly all neoavian stem lineages. We then combined this dataset with 32 DNA sequences of the slowly evolving nuclear RAG1 and RAG2 genes. Morphological results place adzebills as the sister taxon of trumpeters (Psophia) within core Gruiformes and confirm strong support for a Kagu+Sunbittern sister group (99% bootstrap value). Results for analyses of the combined data were identical, and the adzebill+trumpeter clade was supported by a 99% Bayesian clade credibility value. Although the Kagu+Sunbittern sister group is consistent with recent molecular hypotheses, the adzebill+trumpeter group is novel.


Felipe C. Montefeltro (2019)
The Osteoderms of Baurusuchid Crocodyliforms (Mesoeucrocodylia, Notosuchia).
Journal of Vertebrate Paleontology Article: e1594242

Baurusuchidae is a clade of terrestrial crocodyliforms that thrived during the Late Cretaceous in South America. The members of this clade occupied top-predator roles in their habitats. Knowledge about the anatomy, the systematics, and the evolution of baurusuchids has increased profoundly in the past decade. Although aspects of their cranial and postcranial anatomy are becoming clearer, the configuration of the dermal armor remains neglected and little is known about the anatomy of these elements in the clade. The dermal skeleton of baurusuchids is described here in detail in terms of arrangement and morphology, the supposed absence of osteoderms in Pissarrachampsa sera is reevaluated, and a detailed comparison across Crocodyliformes is attempted. The description of the dermal armor, in particular that of the dorsum, revealed an unforeseen variation among baurusuchid taxa, including autapomorphic traits that were added to the diagnosis of taxa. The absence of osteoderms is confirmed for Pissarrachampsa sera based on new specimens, revealing this taxon as the only terrestrial crocodyliform known to lack dermal armor altogether. Comparisons with a diverse range of crocodyliforms revealed that the dorsal shield of baurusuchids is unique among crocodyliforms in terms of arrangement and morphology, and only a few notosuchians approach the condition seen in the clade. This study explores possible biomechanical implications of the unique dorsal shield of baurusuchids and provides information about possible phylogenetic signals, to be tested in future analyses of notosuchian systematics.


Free pdf:

Charles J. Cole & Laurence M. Hardy (2019)
Karyotypes of Six Species of Colubrid Snakes from the Western Hemisphere, and the 140-Million-Year-Old Ancestral Karyotype of Serpentes.
American Museum Novitates 3926: 1-14

Karyotypes are described for six species of snakes from the Western Hemisphere, and comparisons are made with all species of snakes from around the world that have been karyotyped with modern methods. Although there is significant karyotypic variation in snakes, there is one basic karyotype that is shared by members of all families of snakes, representing widely divergent lineages, extending from today back through the evolutionary history of the Serpentes. Long-term survival of the ancestral snake karyotype may be a result of canalization, similar to some ancient chromosomes of turtles.


Free pdf:

Diprosopovenator hilperti, gen. et sp. nov.Â
Sebastian Stumpf, Udo Scheer & JÃrgen Kriwet (2019)
A new genus and species of extinct ground shark, âDiprosopovenator hilperti, gen. et sp. nov. (Carcharhiniformes, âPseudoscyliorhinidae, fam. nov.), from the Upper Cretaceous of Germany.
Journal of Vertebrate Paleontology Article: e1593185

Free pdf:

We describe a new genus and species of extinct ground shark, âDiprosopovenator hilperti, gen. et sp. nov. (Elasmobranchii, Carcharhiniformes), based on a single incomplete skeleton with dentition recovered from basinal marine late Cenomanian (Metoicoceras geslinianum ammonite zone) organic-rich deposits of northern Germany. The new carcharhiniform is characterized by a unique combination of dental morphologies, indicating close architectural resemblance to the family Scyliorhinidae (catsharks). However, the very distinct tooth root morphology readily separates the new taxon from all other scyliorhinids. The extinct Cretaceous carcharhiniform âPseudoscyliorhinus (represented by âPs. schwarzhansi and âPs. reussi) shares tooth root morphologies and vascularization patterns with âDiprosopovenator, gen. nov. We hypothesize that these two sharks form part of an extinct group of carcharhiniforms characterized by a distinct root morphology (viz., low hemiaulacorhize roots with very flat and strongly flared basal faces protruding below the crown labially and mesiodistally and with a well-developed central labiobasal notch). Consequently, we propose a new family of Late Cretaceous carcharhiniforms, âPseudoscyliorhinidae, fam. nov., to include the new taxon, as well as âPseudoscyliorhinus. âPseudoscyliorhinidae, fam. nov., shows a wide European distribution during the Late Cretaceous, ranging from the early Cenomanian to the late Campanian. The longevity of Scyliorhinidae, with a fossil record extending back into the Middle Jurassic, however, remains ambiguous and unresolved; therefore, it may be best to regard the assignment of fossil taxa to Scyliorhinidae as currently uncertain pending further taxonomic work.



Free pdf:

Marcin Machalski, Katarzyna StrÃÅyk & Anna Grabarczyk (2019)
The Cretaceous-Paleogene (K-Pg) Boundary Site at LechÃwka--a New Point on the Geoheritage Map of Southeastern Poland.
Geoheritage (advance online publication)
Free pdf:

A geological section exposed in an abandoned quarry at LechÃwka near CheÅm represents the most complete record of the Cretaceous-Paleogene (K-Pg) boundary interval in Poland. Here, a thin clay layer with impact ejecta marks the K-Pg boundary, making LechÃwka the single place in Poland with a record of the impact that killed off the dinosaurs. Based on the geoheritage evaluation, the LechÃwka outcrop represents a content value of rank intermediate between II and III with the iconographic, symbolic, documental and conceptual contents on the local, regional or even global scale. In spite of the obvious scientific and educational importance of the site, its present state is insufficient to attract 'ordinary' geotourists. In order to ameliorate this situation, transformation of the quarry into an officially protected geosite is called for. Only after a formal, technical and infrastructural upgrade of the LechÃwka site, combined with popularisation in the media, tourist guidebooks, websites and natural history museums, will it have a chance to become a widely recognised point on the Cretaceous geoheritage map of southeastern Poland. The most important and already well-known localities on this map are the subterranean chalk mines at CheÅm, a series of quarries around the mediaeval town of Kazimierz Dolny and a defunct underground phosphorite mine at Annopol, where there are plans for an educational-geotouristic centre.


Free pdf:

Gerilyn S. Soreghan, Michael J. Soreghan & Nicholas G. Heavens (2019)
Explosive volcanism as a key driver of the late Paleozoic ice age.Â
Geology (advance online publication)

Atmospheric CO2 exerts a robust and well-documented control on Earthâs climate, but the timing of glaciation during the late Paleozoic Ice Age (LPIA; ca. 360â260 Ma) is inconsistent with pCO2 reconstructions, hinting at another factor. Stratospheric volcanic aerosols produce a large but temporary negative radiative forcing under modern conditions. Here we examine explosive volcanism over 200 m.y. of Earth history to show that the LPIA corresponded with a sustained increase in volcanism in both tropical and extratropical latitudes. A major peak in explosive volcanism at ca. 300 Ma likely corresponded to stratospheric sulfur-injecting eruptions at least three to eight times more frequent than at present. This level of volcanism created a steady, negative radiative forcing potentially sufficient to initiate and, most critically, sustain icehouse conditions, even under increasing levels of pCO2, and helps resolve discrepancies between glacial timing and CO2 records. Accounting for the radiative forcing effects of CO2 and sulfate indicates that both are required to explain the LPIA, with sulfate producing an especially strong effect at peak icehouse ca. 298â295 Ma. Frequent explosive volcanism would have increased atmospheric acidity, enhancing the reactivity of iron in abundant volcanic ash and glacially generated mineral dust, thus strengthening the climate impact of volcanism through a marine biological pump further primed by feedback with glaciation.


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