Ben Creisler
Some recent non-dino papers:
Rafael Gomes de Souza, Beatriz Marinho HÃrmanseder, Rodrigo Giesta Figueiredo & Diogenes de Almeida Campos (2019)
Description of new dyrosaurid specimens from the Late CretaceousâEarly Paleogene of New Jersey, United States, and comments on Hyposaurus systematics.
Historical Biology (advance online publication)
Dyrosauridae was a successful clade of marine crocodyliforms that survived the CretaceousâPaleogene biotic crises. The most important taxon from North America is Hyposaurus rogersii, a species first described in the mid-19th century based on fragmentary fossils. Several new specimens are described here, comprising material that once belonged to the Yale Peabody Museum (New Haven, USA) but obtained later by L.I. Price and housed in the paleontological collections of the former DivisÃo de Geologia e Mineralogia (Rio de Janeiro, Brazil). The remains include postcranial bones and fragments of a lower jaw. The present work urges for the necessity of a revision about the validity of Hyposaurus rogersii based on the absence of diagnostic features observed in the holotype. The new specimens show new postcranial features that support the importance of the postcranial bones for dyrosaurid systematics.
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Ryoko Matsumoto, Khishigjav Tsogtbaatar, Shinobu Ishigaki, Chinzorig Tsogtbaatar, Zorig Enkhtaivan, and Susan E. Evans (2019)
Revealing body proportions of the enigmatic choristodere reptile Khurendukhosaurus from Mongolia.
Acta Palaeontologica Polonica (in press)
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Khurendukhosaurus is an enigmatic genus of choristodere, recorded from the Lower Cretaceous of East Asia, Mongolia, and Siberian Russia. Until now, it was known only from isolated skull and postcranial elements, limiting comparison with other genera. Three major morphotypes have been recognised within Choristodera: longirostrine neochoristoderes with short-necks, and brevirostrine non-neochoristoderes with either short or long necks. The morphotype of Khurendukhosaurus was uncertain, although it had been inferred to be long-necked, based on cervical and caudal vertebral morphology shared with the Chinese Hyphalosaurus and on the results of phylogenetic analysis that placed it within a clade of Sino-Japanese long-necked taxa. Newly discovered material from the Mongolian type locality, Khuren-Dukh, preserves most major postcranial elements of a single individual. This specimen confirms that Khurendukhosaurus belongs to the long-necked morphotype, in having at least 13 cervical vertebrae. Moreover, a new phylogenetic analysis supports the placement of Khurendukhosaurus as a sister group of the Hyphalosaurus + Shokawa clade. Based on the new material, Khurendukhosaurus is estimated to have been roughly 1 m in total length, placing it at the upper end of the size range for long-necked choristoderes.
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Jade B. Atkins , Robert R. Reisz & Hillary C. Maddin (2019)
Braincase simplification and the origin of lissamphibians.Â
PLoS ONE 14(3): e0213694.
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Dissorophoidea, a group of temnospondyl tetrapods that first appear in the Late Carboniferous, is made up of two clades-Olsoniformes and Amphibamiformes (Branchiosauridae and Amphibamidae)-the latter of which is widely thought to have given rise to living amphibians (i.e., Lissamphibia). The lissamphibian braincase has a highly derived morphology with several secondarily lost elements; however, these losses have never been incorporated into phylogenetic analyses and thus the timing and nature of these evolutionary events remain unknown. Hindering research into this problem has been the lack of phylogenetic analyses of Dissorophoidea that includes both taxonomically dense sampling and specific characters to document changes in the braincase in the lineage leading to Lissamphibia. Here we build on a recent, broadly sampled dissorophoid phylogenetic analysis to visualize key events in the evolution of the lissamphibian braincase. Our ancestral character state reconstructions show a clear, step-wise trend towards reduction of braincase ossification leading to lissamphibians, including reduction of the sphenethmoid, loss of the basioccipital at the Amphibamiformes node, and further loss of both the basisphenoid and the hypoglossal nerve foramina at the Lissamphibia node. Our analysis confirms that the highly derived condition of the lissamphibian braincase is characterized by overall simplification in terms of the number and extent of chondrocranial ossifications.
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RaÃl O. GÃmez and Celeste M. PÃrez-Ben (2019)
Fossils Reveal Long-Term Continuous and Parallel Innovation in the Sacro-Caudo-Pelvic Complex of the Highly Aquatic Pipid Frogs.
Frontiers in Earth Science 7:56
Within the already peculiar Bauplan of anurans, pipid frogs have evolved an array of bizarre features that are commonly linked to their highly aquatic lifestyle. Among the latter, there are several distinctive sacro-caudo-pelvic features shared by extant pipids, which have been regarded as evolutionary novelties taking part of a specialized fore-aft-sliding ilio-sacral joint. Pipids and their kin (pipimorphs) have a rich fossil record documenting 130 million years of uninterrupted evolution in aquatic environments, which, along with our current understanding of their phylogeny and recently available musculoskeletal data, allows us to inquire on the patterns and processes that have led to their distinctive sacro-caudo-pelvic system with a deep-time perspective. Here, we take a phylomorphospace approach based on discrete character matrices and a scaffold tree derived from recent studies, making comparisons of morphospace occupation between pipids and other anurans, and morphospace occupation, disparity, levels of homoplasy, and shared evolving characters between different groups and/or over time across pipimorphs. In doing so, we focus on trends of morphological diversification and discuss the potential role that ecological and developmental constraints might have had in driving the evolution of the sacro-caudo-pelvic complex of pipid frogs. Our main findings reveal a pattern of continuous and parallel innovation early in the history of pipids, followed by arrested evolution of novel morphologies toward the Recent. The latter, in turn, is mirrored by rampant homoplasy in the ilio-sacral sliding joint among extant pipid frogs. This study highlights the importance of fossils in revealing macroevolutionary patterns that will be otherwise veiled based on neontological data alone.
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Also may be of interest:
Carla Piantoni, Carlos A. Navas & Nora R. IbargÃengoytÃa (2019)
A real tale of Godzilla: impact of climate warming on the growth of a lizard.
Biological Journal of the Linnean Society, bly216
Climatic envelope models have predicted the extinction of populations, but few studies have provided accounts of responses of individual species to climate change. Herein, we report on the geographical and temporal variation of growth rates, age at sexual maturity and longevity of two populations of a South American lizard, Tropidurus torquatus. The equator-ward site (forest) was 1-2 ÂC warmer than the pole-ward (urban) site, but both have experienced an increase of ~1-2 ÂC over the last four decades. Operative temperatures revealed warmer microenvironments in the urban area than in the forest. Data on growth confirmed that contemporary lizards were larger than specimens collected in the 1960s. Lizards collected in the 1960s attained sexual maturity at 5 years of age at the urban site and 6-7 years at the forest site, whereas in 2012 animals achieved the minimum adult size 2 years earlier at both localities. Juveniles grew more slowly and adults lived longer in the forest. Lifespan did not show any temporal variation; therefore, the reproductive period has increased in both populations over the last four decades. Although short-term effects might be beneficial to lizards such as T. torquatus, further warming could eventually curtail the hours of activity and ultimately affect species fitness and even survival.
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Tore Grane Klausen, BjÃrn Nyberg & William Helland-Hansen (2019)
The largest delta plain in Earth's history.Â
Geology (advance online publication)
Delta plains host heavily populated and extensive agricultural areas with strong anthropogenic overprints on the natural evolution of these important landforms. Furthermore, modern delta plains have formed over a short geological time frame, representing immature end members to ancient counterparts in Earthâs history--it could thus be argued that these are poor analogues for deciphering the sedimentary rock record. Our present study offers unique insight into the controls and potential extent of ancient deltas by investigation of the Triassic Boreal Ocean, where a large delta plain has been traced across >1.65 Ã 106 km2. We show by comparison that the Triassic Boreal Ocean delta plain is larger than all modern and known ancient counterparts. Supply-driven progradation of this delta system proceeded uninterrupted on a 106 yr scale, indicating relative sea-level stability during this period--in support of a Triassic Greenhouse without pronounced glaciations. Reconstructed paleo-bathymetric relief shows the Triassic Boreal Ocean to have been one order of magnitude smaller than modern equivalents, explaining its vast extent. Despite its extent, the delta plain shows similar geomorphological characteristics to many modern delta plains, supporting their validity as analogues to the ancient, although scales might vary significantly.