Bryan Michael Gee

The cultural landscape of paleontology is dominated by dinosaurs and a few other charismatic clades that are more likely to be depicted in media and to be recognized by the public. There is a prevailing belief among researchers that these biases extend to scholarly publishing - that certain clades enjoy a 'taxonomic advantage' that renders them more likely to be published in high-impact journals like Nature and Science. Given the importance of publishing in high-impact journals for career advancement, quantitative testing of this hypothesis can inform on potential biases in this area. I examined articles describing new species that were published between 2000 and mid-2026 in one of thirteen journals (n = 4,248 articles, 8,331 new species), ranging from high-profile, multidisciplinary titles like Nature to lower-profile, specialist titles like the Journal of Paleontology. Comparisons of the taxonomic composition of new species between journals revealed a positive correlation between a journal's prestige (approximated by its impact factor) and the relative proportion of new species that belong to charismatic clades. Avemetatarsalians and mammaliamorphs represent more than 50% of new species in Nature and Science but less than 15% of new species in the control group of paleontological journals. These results provide support for the perception that there is a bias between extinct taxa as it relates to publication in high-impact journals. Given the potential for researchers to accrue cumulative advantage through publishing in prestigious journals, bias in favor of charismatic clades creates the potential for opportunities and knowledge generation to become increasingly skewed and consolidated towards these clades, at the expense of less charismatic clades and the people studying them. This threatens the discipline's ability to continue to construct a holistic understanding of the full history of life that can be disseminated to the public. Further attention should be directed towards examining potential biases in paleontological publications as the primary currency in academia.

This preprint introduces and describes a living database, TEMNOS (Temnospondyl Evolution, Morphology, Nomenclature, and Other Stuff) comprised of individual curated datasets, that broadly encompasses data pertaining to temnospondyls, a diverse, globally distributed, and temporally long-ranging clade of non-amniotes ('amphibians' in a broad sense) that has been widely linked to the origin of modern amphibians. The database has no "designed" or "prescribed" usage (i.e. is not linked to a singular manuscript that is actively in development or review) but builds upon smaller-scale datasets that I have collated over the years as part of other projects. It is being developed, formalized, and published now in recognition of the importance and frequent inclusion of temnospondyls in broad macroevolutionary studies across broad temporal, geographic, and taxonomic scales and in recognition of the current shortcomings of other synoptic works or large-scale databases that are presently relied upon for scientific analyses. The database is intended to be continuously refined and grown in various ways in order to overcome the common challenge of a static nature of academic publications and to provide a high-quality set of reference materials for a wide array of information around temnospondyl paleobiology and study. TEMNOS is intended to be a collaborative and responsive resource and is intended to be used by more audiences than just academics and for more purposes than just scholarly research. This preprint serves as the descriptor of the conceptual basis and motivation for TEMNOS and as a means of crediting primary data generators through an indexable output. It will be modified periodically to account for major developments of the database and to keep the cited literature current, as well as to acknowledge any new contributors/authors.

Aspidosaurus is a Permo-Carboniferous dissorophid characterized by a single series of dorsally keeled osteoderms. It is simultaneously one of the best-known dissorophids, with dozens of referred specimens, and one of the least understood dissorophids, with most specimens comprising isolated osteoderms and neural spines, and almost all of the seven nominal species being of questionable validity and genus-level placement. Aspidosaurus has come to represent a general morphotype (‘wastebasket taxon’) that includes any specimen with a single series of dorsally keeled osteoderms. This paradigm stems, in part, from the loss of the holotype of the type species, Aspidosaurus chiton. The antiquity and brevity of the original description hinder interpretation of the large and morphologically diverse suite of referred specimens. Here we document a previously undescribed partial skeleton from the lower Permian (Cisuralian) of Texas that shares many features with the lost holotype of A. chiton, exhibits no marked differences, and can be differentiated from all other dissorophids. The new specimen is designated as the neotype of A. chiton, and Aspidosaurus is re-diagnosed and restricted to the type species, in order to mitigate its longstanding role as a wastebasket taxon and to lay the foundation for revision of previously referred material.

‘Aspidosaurus’ novomexicanus is a poorly known dissorophid represented by the holotype (YPM VP 810), a badly preserved partial skeleton from Permo-Carboniferous deposits of New Mexico. Compared to Paleozoic dissorophid records in other parts of North America like Texas and Oklahoma, the New Mexico record remains relatively sparse and low in taxic diversity. Additionally, ‘A.’ novomexicanus is likely one of the earliest known records of dissorophids in North America. However, due to poor preservation of the holotype and a convoluted taxonomic history of species- and genus-level referral of specimens to this taxon and to other dissorophids, the concept of ‘A.’ novomexicanus and whether the holotype is sufficiently diagnostic to merit continued designation as a valid taxon remain unclear. Recent revision of Aspidosaurus demonstrates that this species does not belong in the genus, providing an impetus for a reassessment. Here I redescribe YPM VP 810 and situate it within the contemporary framework of dissorophid anatomy and taxonomy. Based on these findings, I conclude that the holotype is not diagnostic, rendering ‘Aspidosaurus novomexicanus’ to be designated as a nomen dubium, although it is possible that it may be conspecific with ‘Broiliellus’ reiszi.

Data compilations expand the scope of research; however, data citation practice lags behind advances in data use. It remains uncommon for data users to credit data producers in professionally meaningful ways. In paleontology, databases like the Paleobiology Database (PBDB) enable assessment of patterns and processes spanning millions of years, up to global scale. The status quo for data citation creates an imbalance wherein publications drawing data from the PBDB receive significantly more citations (median: 4.3 ± 3.5 citations/year) than the publications producing the data (1.4 ± 1.3 citations/year). By accounting for data reuse where citations were neglected, the projected citation rate for data-provisioning publications approached parity (4.2 ± 2.2 citations/year) and the impact factor of paleontological journals ( n = 55) increased by an average of 13.4% (maximum increase = 57.8%) in 2019. Without rebalancing the distribution of scientific credit, emerging “big data” research in paleontology—and science in general—is at risk of undercutting itself through a systematic devaluation of the work that is foundational to the discipline.

Living amphibians (Lissamphibia) include frogs and salamanders (Batrachia) and the limbless worm-like caecilians (Gymnophiona). The estimated Palaeozoic era gymnophionan–batrachian molecular divergence¹ suggests a major gap in the record of crown lissamphibians prior to their earliest fossil occurrences in the Triassic period^2–6. Recent studies find a monophyletic Batrachia within dissorophoid temnospondyls^7–10, but the absence of pre-Jurassic period caecilian fossils^11,12 has made their relationships to batrachians and affinities to Palaeozoic tetrapods controversial^1,8,13,14. Here we report the geologically oldest stem caecilian—a crown lissamphibian from the Late Triassic epoch of Arizona, USA—extending the caecilian record by around 35 million years. These fossils illuminate the tempo and mode of early caecilian morphological and functional evolution, demonstrating a delayed acquisition of musculoskeletal features associated with fossoriality in living caecilians, including the dual jaw closure mechanism^15,16, reduced orbits¹⁷ and the tentacular organ¹⁸. The provenance of these fossils suggests a Pangaean equatorial origin for caecilians, implying that living caecilian biogeography reflects conserved aspects of caecilian function and physiology¹⁹, in combination with vicariance patterns driven by plate tectonics²⁰. These fossils reveal a combination of features that is unique to caecilians alongside features that are shared with batrachian and dissorophoid temnospondyls, providing new and compelling evidence supporting a single origin of living amphibians within dissorophoid temnospondyls.

Metoposaurids are a clade of large-bodied temnospondyls commonly found in non-marine Late Triassic deposits across northern Pangea. Three taxa are known from North America: Anaschisma browni, Apachesaurus gregorii, and “Metoposaurus” bakeri. While the osteology of most metoposaurids has been recently revised, that of a few taxa, including “Metoposaurus” bakeri remains poorly characterized. This taxon was formally described in 1931 as “Buettneria bakeri,” and its taxonomy has remained in flux ever since then. “Metoposaurus” bakeri is the earliest appearing metoposaurid in North America (Carnian of Texas), and Metoposaurus has frequently been utilized as an index taxon of the Otischalkian estimated holochron (‘land vertebrate faunachron’) and for biostratigraphic correlations with other geographic regions. The taxonomy of this species is therefore relevant for both taxonomic experts and biostratigraphers. Here we redescribe all material from the type locality of “M.” bakeri, the Elkins Place bone bed, and perform a phylogenetic analysis using a revised matrix assembled from several previous studies. Anatomical comparisons and phylogenetic analyses do not support placement in either Metoposaurus, a taxon otherwise only found in Europe, or Anaschisma, the only other large-bodied taxon from North America. Therefore, we erect a new genus, Buettnererpeton gen. nov., to accommodate this species. Metoposaurus is consequently absent from North America, and this genus cannot be used in global biostratigraphy. Phylogenetic analyses provide evidence that the phylogeny of the Metoposauridae remains extremely labile, with drastic differences in topological resolution and structure being linked to just a handful of characters and scores. Metoposaurids’ morphological conservatism and the increased recognition of intraspecific variation thus continue to be major confounds to elucidating the evolutionary history of this clade.