PALEONTOLOGY IN JANUARY, 2025

ABSTRACT

Specimens of the pachycephalosaurine Stygimoloch spinifer from the Upper Maastrichtian Ferris Formation in south-central Wyoming’s Hanna Basin represent the southernmost record of this uncommon marginocephalian. UW 26525 is a partial, but diagnostic left squamosal that extends the geographic range of S. spinifer 100 km to the south from the Lance Formation in eastern Wyoming. It was collected from deposits that accumulated approximately 320 k.y. before the K/Pg boundary bolstering the hypothesis that S. spinifer is taxonomically distinct from Pachycephalosaurus wyomingensis and only occurred during the final 500 k.y. of the Maastrichtian. Two pachycephalosaurine teeth are also referrable to S. spinifer and were preserved approximately 370 and 457 k.y. prior to the K/Pg boundary. These specimens emphasize the value of isolated, fragmentary, but taxonomically identifiable remains from areas and horizons in which fossils are rare or unreported. Furthermore, they support the hypothesis that latest Cretaceous dinosaurian communities were generally cosmopolitan in the North American Western Interior, but the low abundance of S. spinifer in fossil collections suggests that the identification of clear palaeobiogeographic trends remains a challenge.

LINK(S)

https://www.scup.com/doi/10.18261/let.57.4.7
https://www.scup.com/doi/epdf/10.18261/let.57.4.7

ABSTRACT

Alvarezsauria is a group of morphologically distinctive, medium- to small-sized later-diverging coelurosaurian theropod dinosaurs, whose record ranges from the Late Jurassic to the Late Cretaceous. This clade had a widespread distribution in Laurasia in what is now Europe, Asia, and North America, although there are also several Cretaceous taxa from Gondwana in what is now Argentina that all belong to the family Alvarezsauridae. Although alvarezsaurid taxonomic diversity and anatomical knowledge has expanded over the last decade, alvarezsaurid internal phylogenetic relationships remain highly debated. In this contribution, we describe new alvarezsaurid material and review previously reported alvarezsaurid specimens from the middle Campanian—lower Maastrichtian Allen Formation discovered at the Salitral Ojo de Agua locality in Río Negro province, Patagonia, Argentina. Although these specimens were collected at different times without precise original provenance information, here we gathered X-ray diffraction data of the associated sediments that now suggests that all of these specimens come from the same site and stratigraphic level as the holotype of the alvarezsaurid Bonapartenykus ultimus. Based on this new provenance information and the morphological similarity of the considered specimens, here we tentatively refer them to the genus Bonapartenykus. These newly referred specimens add to the record of this genus and shed light on the body plan of the alvarezsaurid clade Patagonykinae by permitting a more complete reconstruction of the neck, pectoral girdle, hindlimb, and tail.

LINK(S)

https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0308366

ABSTRACT

New ornithomimosaur material discovered from the Upper Cretaceous Cerro del Pueblo Formation (CdP) of Coahuila, Mexico represents a new genus and species of Ornithomimidae. The new taxon, Mexidracon longimanus sp. nov., is represented by an individual preserving axial and appendicular elements. M. longimanus is characterised by the following combination of characters: extreme lengthening of the metacarpals that are longer than the metatarsals, proximal end of metacarpal II with a narrow subtriangular outline, a pubic peduncle of the ilium with a flared, zig-zag articular margin that is wider anteriorly than posteriorly and an ischiadic peduncle that is similar in size to the pubic peduncle, a pubic boot where the distal margin of the anterior expansion is separated from the shaft by a deep notch, a femur that is slightly longer than the tibia, an arctometatarsalian pes, a metatarsal II that has a D-shaped cross-section, and a metatarsal IV longer than metatarsal II, among other features. A phylogenetic analysis places M. longimanus within Ornithomimidae forming a polytomic relationship with other members of this clade. The finding of M. longimanus adds to the increasing diversity and paleobiogeographic distribution of the group during the Campanian of southern Laramidia. The ornithomimosaur record of the CdP represents yet another instance of the coexistence of ornithomimids and deinocheirids spanning a wide range of body sizes within this clade of ‘ostrich’ dinosaurs.

LINK(S)

https://www.sciencedirect.com/science/article/abs/pii/S0195667125000102

ABSTRACT

Extrapolating from skeletal/total mass ratios, the gigantic Paleogene whale Perucetus colossus has been estimated to have massed 85 to 341 tonnes, approaching and even exceeding the blue whale (Balaenoptera musculus). Such a large variation in body mass lacks the precision needed for analytical accuracy and is therefore not of technical value. Despite sufficient remains for a much more accurate volumetric model, none was produced for robust testing their procedure. A subsequent paper downscaled Perucetus to 60 to 70 tonnes as the most probable estimate. To better assess the question, we have produced multiview profile-skeletals for Perucetus and other large marine mammals in the most extensive such effort to date. These include the first accurate restorations of a number of large marine mammals. Perucetus is restored using the proportions of heavy boned pachycetine basilosaurs. Cross comparisons and attempts to illustrate the extinct whale's realistic volume leave no doubt that the Perucetus holotype did not reach the cetacean heavyweight category. A length of 15 to 16 m and a mass of 35 to 40 tonnes is more in line with its known anatomy. This result was affirmed by recalculations of skeletal/total mass relationships in large pachyosteosclerotic marine mammals, which suggest the method can produce useful estimates if conducted properly. Although their initial size expansion was remarkably rapid, basal cetaceans did not balloon to super whale dimensions just a few million years after the initial evolution of the fully marine forms. Evolution of extremely large body size exceeding 50 tonnes did not occur until the late Neogene. The biggest whale of all time, the blue, is not likely to exceed ~30 m and 200 tonnes. It is emphasized that anatomical knowledge translated into technical volumetric models remains the most critical means of restoring the mass of extinct organisms.

LINK(S)

https://palaeo-electronica.org/content/2025/5431-trimming-down-perucetus

https://palaeo-electronica.org/content/pdfs/1435.pdf

ABSTRACT

The affinities of the Tully monster (Tullimonstrum gregarium), from the late Carboniferous Mazon Creek Lagerstätte (~309 Ma) of Illinois, have been debated since its discovery. Tullimonstrum is up to ~35 cm long with a long proboscis ending in pincers and an elongate tapering body with caudal dorsal and ventral fins. This iconic evolutionary enigma or ‘weird wonder’ has been suggested to relate to arthropods, various ‘worms’, tunicates, conodonts, lancelets, vetulicolians and even vertebrates, but it may be a mollusc (Caenogastropoda) such as a pterotracheid (heteropod) pelagic gastropod, similar to Pterotrachea coronata (the ‘sea elephant’).

LINK(S)

https://www.science.org/doi/10.1126/sciadv.adp5243

ABSTRACT

How snow leopard gradually adapted to the extreme environments in Tibet remains unexplored due to the scanty fossil record in Tibet. Here, we recognize five valid outside-Tibet records of the snow leopard lineage. Our results suggest that the snow leopard dispersed out of the Tibetan Plateau multiple times during the Quaternary. The osteological anatomy of the modern snow leopard shows adaptation to the steep slope and, to a lesser extent, cold/high-altitude environment. Fossils and phylogeny suggest that the snow leopard experienced a gradual strengthening of such adaptation, especially since the Middle Pleistocene (~0.8 million years). Species distribution modeling suggests that the locations of the fossil sites are not within most suitable area, and we argue that local landscape features are more influential factors than temperature and altitude alone. Our study underscores the importance of integrating morphology, fossil records, and species distribution modeling, to comprehensively understand the evolution, ecology, and inform conservation strategies for endangered species.

LINK(S)

https://www.science.org/doi/10.1126/sciadv.adp5243

ABSTRACT

The first partial skeleton of a carcharodontosaurid theropod was described from the Egyptian Bahariya Oasis by Ernst Stromer in 1931. Stromer referred the specimen to the species Megalosaurus saharicus, originally described on the basis of isolated teeth from slightly older rocks in Algeria, under the new genus name Carcharodontosaurus saharicus. Unfortunately, almost all of the material from the Bahariya Oasis, including the specimen of Carcharodontosaurus was destroyed during World War II. In 1996, a relatively complete carcharodontosaurid cranium was described from similar aged rocks in Morocco and designated the neotype of the species Carcharodontosaurus saharicus in 2007. However, due to the destruction of the original material, comparisons of the neotype to the Egyptian fossils have so far only been done cursorily. A detailed reexamination of the available information on the Egyptian carcharodontosaurid, including a previously undescribed photograph of the exhibited specimen, reveals that it differs from the Moroccan neotype in numerous characters, such as the development of the emargination of the antorbital fossa on the nasals, the presence of a horn-like rugosity on the nasal, the lack of a dorsoventral expansion of the lacrimal contact on the frontals, and the relative enlargement of the cerebrum. The referability of the Egyptian specimen to the Algerian M. saharicus is found to be questionable, and the neotype designation of the Moroccan material for C. saharicus is accepted here under consideration of ICZN Atricle 75, as it both compares more favorably to M. saharicus and originates from a locality closer to the type locality. A new genus and species, Tameryraptor markgrafi gen. et sp. nov, is proposed for the Egyptian taxon. The theropods of the Bahariya Oasis and the Moroccan Kem Kem Group are thus not as closely related as previously thought, and the proposed faunal similarities between these two strata need further examination.

LINK(S)

https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0311096

ABSTRACT

The Late Cretaceous through Paleogene fossil record for North American eusuchians is remarkable in that it indicates high levels of survivorship across the Cretaceous–Paleogene (K–Pg) boundary, as well as an increase in diversity through the early Eocene. Despite the clade’s continued existence, gaps remain in its fossil record, particularly near the K–Pg boundary and in Colorado. A eusuchian from the lower Paleocene Denver Formation of Corral Bluffs is represented by specimens identified as Borealosuchus sternbergii. Here, we provide anatomical descriptions and comparisons supported by micro-CT scan data of three partial crania. We conduct a phylogenetic analysis, the results of which are influenced by the potential sub-adult ontogenetic stage of the specimens and species-level assignment is preliminary. The specimens fill both geographic and temporal gaps in the record of the Borealosuchus species complex as the first specimens from the earliest Paleocene of Colorado. These additions highlight the uncertainty in phylogenetic relationships among the Borealosuchus species complex, the importance of taking ontogenetic stage into account when assessing such relationships, and help constrain biogeographic dispersal patterns and ecological niche occupation of the clade.

LINK(S)

https://www.tandfonline.com/doi/full/10.1080/02724634.2024.2434214

ABSTRACT

Dzharacursor gen. nov. is established for the reception of Archaeornithomimus(?) bissektensis Nesov, Citation1995 from the Upper Cretaceous (Turonian) Bissekty Formation of Uzbekistan. Dzharacursor bissektensis is represented by cranial elements and many isolated postcranial bones that show considerable ontogenetic and some individual variation. Several of the morphological characters previously hypothesized as autapomorphies for Qiupalong henanesis and Aepyornithomimus tugrikinensis are found to be variable in the hypodigm for Dzaracursor bissektensis. Dzharacursor bissektensis is one of the oldest known ornithomimids in Asia. Phylogenetic analysis places this taxon at the base of the ornithomimid radiation, but more derived than Archaeornithomimus asiaticus.

LINK(S)

https://www.tandfonline.com/doi/full/10.1080/02724634.2024.2433759

ABSTRACT

The origin of Dinosauria is thought to be deeply rooted in the high-latitude southern hemisphere (Gondwana). Nearly 6–10 million years separates Gondwanan faunas and the oldest known dinosaur occurrence in the northern hemisphere (Laurasia). However, our understanding of dinosaur origins is biased by an apparent absence of Carnian-aged (237–227 Mya) Laurasian terrestrial strata. Here we report on UWGM 1975/UWGM 7549, the oldest known Laurasian dinosaur Ahvaytum bahndooiveche gen. et sp. nov., and UWGM 7407/UWGM 7550, a silesaurid, from palaeoequatorial deposits of the lower Popo Agie Formation, Wyoming, USA. High-precision radioisotopic detrital ages [e.g. ≤229.04 ± 0.24 Mya (2σ)] from the upper Popo Agie Formation constrain an age-depth model that predicts a ~230 Mya age for UWGM 1975, making Laurasia’s first unequivocal Carnian-aged sauropodomorph dinosaur comparable in age to the oldest dinosaur faunas of Gondwana. The presence of a ~230 Mya, low-latitude, early sauropodomorph from the northern hemisphere, along with a silesaurid, challenges the hypothesis of a delayed dinosaurian dispersal out of high-latitude Gondwana. These data fill a critical gap in the early record of sauropodomorph dinosaur evolution and demonstrate widespread geographic distribution by the mid-late Carnian.

LINK(S)

https://academic.oup.com/zoolinnean/article/203/1/zlae153/7942678?login=false

https://academic.oup.com/zoolinnean/article-pdf/203/1/zlae153/61329553/zlae153.pdf

ABSTRACT

Caves are primary sites for studying human and animal subsistence patterns and genetic ancestry throughout the Palaeolithic. Iberia served as a critical human and animal refugium in Europe during the Last Glacial Maximum (LGM), 26.5 to 19 thousand years before the present (cal kya). Therefore, it is a key location for understanding human and animal population dynamics during this event. We recover and analyse sedimentary ancient DNA (sedaDNA) data from the lower archaeological stratigraphic sequence of El Mirón Cave (Cantabria, Spain), encompassing the (1) Late Mousterian period, associated with Neanderthals, and (2) the Gravettian (c. 31.5 cal kya), Solutrean (c. 24.5–22 cal kya), and Initial Magdalenian (d. 21–20.5 cal kya) periods, associated with anatomically modern humans. We identify 28 animal taxa including humans. Fifteen of these taxa had not been identified from the archaeozoological (i.e., faunal) record, including the presence of hyenas in the Magdalenian. Additionally, we provide phylogenetic analyses on 70 sedaDNA mtDNA genomes of fauna including the densest Iberian Pleistocene sampling of C. lupus. Finally, we recover three human mtDNA sequences from the Solutrean levels. These sequences, along with published data, suggest mtDNA haplogroup continuity in Iberia throughout the Solutrean/Last Glacial Maximum period.

LINK(S)

https://www.nature.com/articles/s41467-024-55740-7
https://www.nature.com/articles/s41467-024-55740-7.pdf