Ben Creisler
Some recent non-dino papers (some free and some paywalled) that may be of interest:
Free pdf:
How do large and unique brains evolve? Historically, comparative neuroanatomical studies have attributed the evolutionary genesis of highly encephalized brains to deviations along, as well as from, conserved scaling relationships among brain regions. However, the relative contributions of these concerted (integrated) and mosaic (modular) processes as drivers of brain evolution remain unclear, especially in non-mammalian groups. While proportional brain sizes have been the predominant metric used to characterize brain morphology to date, we perform a high-density geometric morphometric analysis on the encephalized brains of crown birds (Neornithes or Aves) compared to their stem taxa--the non-avialan coelurosaurian dinosaurs. When analyzed together with developmental neuroanatomical data of model archosaurs (Gallus, Alligator), crown birds exhibit a distinct allometric relationship that dictates their brain evolution and development. Furthermore, analyses by neuroanatomical regions reveal that the acquisition of this derived shape-to-size scaling relationship occurred in a mosaic pattern, where the 'avian'-grade optic lobe and cerebellum evolved first among non-avialan dinosaurs, followed by major changes to the evolutionary and developmental dynamics of cerebrum shape after the origin of Avialae. Notably, the brain of crown birds is a more integrated structure than non-avialan archosaurs, implying that diversification of brain morphologies within Neornithes proceeded in a more coordinated manner, perhaps due to spatial constraints and abbreviated growth period. Collectively, these patterns demonstrate a plurality in evolutionary processes that generate encephalized brains in archosaurs and across vertebrates.
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Apteryx littoralis sp. nov.
We describe Apteryx littoralis sp. nov., a new species of kiwi based on a 1-million-year-old tarsometatarsus from shallow marine sediment in the North Island of New Zealand. The fossil is very similar to the tarsometatarsi of living kiwi species, most closely resembling Apteryx rowi and A. mantelli in size and shape, but differs in being stouter, with proportionally narrower proximal and distal ends. The new fossil is the second oldest known record of kiwi. It demonstrates a relatively conservative kiwi morphology since the mid-Pleistocene.
http://zoobank.org/References/cefc907d-0c1d-44dc-83c5-5799f5d6d3d2
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Free pdf:
Palaeovaranus lismonimenos n. sp. Â
Pseudeumeces kyrillomethodicus n. sp.
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Georgios L. GEORGALIS, Andrej ÄERÅANSKÃ & Jozef KLEMBARA (2021)
Osteological atlas of new lizards from the Phosphorites du Quercy (France), based on historical, forgotten, fossil material.
in STEYER J.-S., AUGÃ M. L. & MÃTAIS G. (eds), Memorial Jean-Claude Rage: A life of paleo-herpetologist.Â
GEODIVERSITAS 43(9): 219-293
doi:
https://doi.org/10.5252/geodiversitas2021v43a9https://sciencepress.mnhn.fr/en/periodiques/geodiversitas/43/9Free pdf:
https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/g2021v43a9.pdfA long-forgotten, old collection of lizards from the Phosphorites du Quercy in southern France, housed in the Naturhistorisches Museum in Vienna (NHMW), is described in detail in this paper. The material, consisting of several almost complete cranial and postcranial disarticulated elements, originates from different, imprecisely known localities. Nevertheless, the completeness and exceptional preservation of many of these specimens permitted the identification of new taxa, as well as the recognition and better understanding of novel anatomical features of previously described forms. Among the specimens, the material described herein and referred to Cadurcogekko cf. piveteaui ranks among the most complete cranial remains of Paleogene gekkotans. A clarification about the type material of the previously described species Cadurcogekko verus Bolet, Daza, Augà & Bauer, 2015, is provided. A new species of lacertids is established, Pseudeumeces kyrillomethodicus n. sp. Additional, large lacertid material is referred to Mediolacerta AugÃ, 2005, representing also the largest one attributable to this genus. At least two glyptosaurine taxa are present in this collection, among which, the genus Paraplacosauriops Augà & Sullivan, 2006, is represented by exceptional cranial material, referred to Paraplacosauriops quercyi (Filhol, 1882). The completeness of the cranial material of Paraplacosauriops permits a more comprehensive understanding of its maxillary and mandibular anatomy. A detailed documentation of cranial and postcranial material for the genus Palaeovaranus Zittel, 1887-1890, is conducted. The new maxilla described herein allows a better understanding of the peculiar maxillary features of the genus Palaeovaranus. Emended diagnoses are provided for the genus Palaeovaranus and its type species Palaeovaranus cayluxi Zittel, 1887-1890. The parietal morphology of Palaeovaranus is analyzed in detail and intraspecific variation in this element is assessed. A new species of Palaeovaranus is established, Palaeovaranus lismonimenos n. sp., on the basis of an almost complete parietal that can be differentiated from that of Palaeovaranus cayluxi on the basis of a number of distinctive features. Additional, previously published specimens from Quercy are here referred to Palaeovaranus lismonimenos n. sp., representing younger individuals of this species, and photographs of this material is provided for the first time. The diversity of platynotans in the Paleogene of Europe is discussed and their distinction on the basis of parietal morphology is provided. According to the new emended diagnosis for Palaeovaranus, the genus Melanosauroides Kuhn, 1940, is revalidated herein to accommodate Melanosauroides giganteus Kuhn, 1940, from the late early or middle Eocene of Geiseltal, Germany. So far, Melanosauroides giganteus is solely known from its type area in Geiseltal, and all previously supposed occurrences of this taxon in Quercy are discarded. Abundant anguimorph vertebral material is referred to Placosaurus sp., Melanosaurini indet., Anguinae indet., Palaeovaranus sp., Saniwa sp., and Anguimorpha indet., although it is highlighted that certain of these referrals should be taken into consideration with caution. Especially, the problem of certain large isolated lizard vertebrae from Quercy is addressed; a tentative, potential distinction between vertebrae of the genera Palaeovaranus and Placosaurus Gervais, 1848-1852, is suggested, although admittedly only articulated skeletons of these genera may confirm or refute such taxonomic referrals. The importance of fossil squamates from the area of the Phosphorites du Quercy is highlighted. Detailed figuring of the specimens is provided through the means of both photography and micro-CT scanning, with 3D models of the most significant material also presented. This is the first time that micro-CT scanning is conducted on fossil squamates from Quercy. The many figures provided in this paper may serve as a pictorial key guide for fossil lizards from the Paleogene of Europe.
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Mammals are the only living members of the larger clade Synapsida, which has a fossil record spanning 320 Ma. Despite the fact that much of the ecological diversity of mammals has been considered in the light of limb morphology, the ecological comparability of mammals to their fossil forerunners has not been critically assessed. Because of the wide use of limb morphology in testing ecomorphological hypothesis about extinct tetrapods, we sought: (i) to estimate when in synapsid history, modern mammals become analogues for predicting fossil ecologies; (ii) to document examples of ecomorphological convergence; and (iii) to compare the functional solutions of distinct synapsid radiations. We quantitatively compared the forelimb shapes of the multiple fossil synapsid radiations to a broad sample of extant Mammalia representing a variety of divergent locomotor ecologies. Our results indicate that each synapsid radiation explored different areas of morphospace and arrived at functional solutions that reflected their distinctive ancestral morphologies. This work counters the narrative of non-mammalian synapsid forelimb evolution as a linear progression towards more mammalian morphologies. Instead, a disparate array of early-evolving shapes subsequently contracted towards more mammal-like forms.
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Free pdf:
Retrotransposons, a large and diverse class of transposable elements that are still active in humans, represent a remarkable force of genomic innovation underlying mammalian evolution. Among the features distinguishing mammals from all other vertebrates, the presence of a neocortex with a peculiar neuronal organization, composition and connectivity is perhaps the one that, by affecting the cognitive abilities of mammals, contributed mostly to their evolutionary success. Among mammals, hominids and especially humans display an extraordinarily expanded cortical volume, an enrichment of the repertoire of neural cell types and more elaborate patterns of neuronal connectivity. Retrotransposon-derived sequences have recently been implicated in multiple layers of gene regulation in the brain, from transcriptional and post-transcriptional control to both local and large-scale three-dimensional chromatin organization. Accordingly, an increasing variety of neurodevelopmental and neurodegenerative conditions are being recognized to be associated with retrotransposon dysregulation. We review here a large body of recent studies lending support to the idea that retrotransposon-dependent evolutionary novelties were crucial for the emergence of mammalian, primate and human peculiarities of brain morphology and function.Â
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Free pdf:
Lemurs once rivalled the diversity of rest of the primate order despite their confinement to the island of Madagascar. We test the adaptive radiation model of Malagasy lemur diversity using a novel combination of phylogenetic comparative methods and geometric methods for quantifying tooth shape.
Results
We apply macroevolutionary model fitting approaches and disparity through time analysis to dental topography metrics associated with dietary adaptation, an aspect of mammalian ecology which appears to be closely related to diversification in many clades. Metrics were also reconstructed at internal nodes of the lemur tree and these reconstructions were combined to generate dietary classification probabilities at internal nodes using discriminant function analysis. We used these reconstructions to calculate rates of transition toward folivory per million-year intervals. Finally, lower second molar shape was reconstructed at internal nodes by modelling the change in shape of 3D meshes using squared change parsimony along the branches of the lemur tree. Our analyses of dental topography metrics do not recover an early burst in rates of change or a pattern of early partitioning of subclade disparity. However, rates of change in adaptations for folivory were highest during the Oligocene, an interval of possible forest expansion on the island.
Conclusions
There was no clear phylogenetic signal of bursts of morphological evolution early in lemur history. Reconstruction of the molar morphologies corresponding to the ancestral nodes of the lemur tree suggest that this may have been driven by a shift toward defended plant resources, however. This suggests a response to the ecological opportunity offered by expanding forests, but not necessarily a classic adaptive radiation initiated by dispersal to Madagascar.
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Protoadapis andrei Âsp. nov.
Pronycticebus cosensis sp. nov. Â
Quercyloris eloisae gen. et sp. nov.
Marc Godinot, CÃcile Blondel, Gilles Escarguel, Carine LÃzin, Thierry PÃlissiÃ, Rodolphe Tabuce & Dominique Vidalenc (2021)
Primates and Plesiadapiformes from Cos (Eocene; Quercy, France).
Geobios (advance online publication)
doi:
https://doi.org/10.1016/j.geobios.2021.03.004 https://www.sciencedirect.com/science/article/abs/pii/S0016699521000280A new fauna has been collected from a fissure filling named Cos in the Quercy region, southwestern France. It includes four primate species and a plesiadapiform. The cercamoniine adapiform Protoadapis andrei Godinot and Vidalenc, nov. sp., is represented by material that adds to our knowledge of the genus Protoadapis for the upper canine, upper molars and other morphological details. It appears more primitive than P. brachyrhynchus from the Old Quercy Collections. The other cercamoniine Pronycticebus cosensis Godinot and Vidalenc, nov. sp., offers insight on intraspecific variations and other details of the genus. Both species suggest a bushy evolution within these genera. Two teeth document the presence of a third cercamoniine, Anchomomys sp. indet. The new microchoerid Quercyloris eloisae Godinot and Vidalenc, nov. gen., nov. sp., has very primitive characters and seems to document a primitive member of the Pseudoloris clade. A poorly documented paromomyid plesiadapiform is distinct enough to be named Arcius moniquae Godinot and Vidalenc, nov. sp. It represents the first discovery of a plesiadapiform in the Quercy fossil record and makes a link with paromomyids surviving until the late Lutetian European Mammal Paleogene MP 13 reference level. The primates indicate a broad age interval between MP 10 (late Ypresian) and MP 12 (mid-Lutetian). The identification of the same species of Pronycticebus and of the new genus in the Vielase fauna suggests more precisely the MP 10âMP 11 (late Ypresianâearly Lutetian) interval.
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Maeva J. Orliac & J. G. M. Thewissen (2021)
The Endocranial Cast of Indohyus (Artiodactyla, Raoellidae): The Origin of the Cetacean Brain.
Journal of Mammalian Evolution (advance online publication)
DOI:
https://doi.org/10.1007/s10914-021-09552-xhttps://link.springer.com/article/10.1007/s10914-021-09552-xWe present the first description of the endocranial cast of the small raoellid artiodactyl Indohyus indirae. Raoellidae are sister group to Cetacea and the new morphological observations allow for outlining some of the early steps of the evolutionary history of the cetacean brain. The combination of primitive artiodactyl features and typical cetacean characters is unique about the Indohyus endocast. The fact that it presents the symplesiomorphic brain pattern observed in earliest Artiodactyla indicates that the cetacean brain derives from a very simple, plesiomorphic brain, with simple neocortical folding pattern, widely exposed midbrain, and concurrent small neocortex expansion. On the other hand, the Indohyus endocast shows characters that also occur in early cetaceans. These include modifications of the olfactory tract with narrow, elongated olfactory bulbs and peduncles, accompanied by a posterior location of the braincase in the cranium. The derived endocranial cast features of Indohyus mainly reflect changes in cranial architecture and these are most probably associated with modifications of the masticatory apparatus and a shift in diet. Indohyus meninges were very thin like in most terrestrial artiodactyls and it had no extensive rostral or lateral retia mirabilia. It however shows a branching pattern of ramification of intraosseous blood sinuses above the cerebellum that might represent the initial development of the caudal venous rete mirabile that would have colonized the endocranial cavity later on, in early archaeocetes.
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The olfactory organs of two African lungfishes, Protopterus amphibius and P. dolloi, were investigated using a stereo microscope and a compound light microscope and were described anatomically, histologically, and histochemically. Like other lungfishes, these species present the following general features: i) elongated olfactory chamber (OC), ii) anterior nostril at the ventral tip of the upper lip, iii) posterior nostril on the palate of the oral cavity, iv) lamellae with multiple cell types such as olfactory receptor neurons, supporting cells, basal cells, lymphatic cells, and mucous cells (MC), and vi) vomero-like epithelial crypt (VEC) made of glandular epithelium (GE) and crypt sensory epithelium. Some of these features exhibit differences between species: MCs are abundant in both the lamellar and inner walls of the OC in P. amphibius but occur only in lamellae in P. dolloi. On the other hand, some between feature differences are consistent across species: the GE of both P. amphibius and P. dolloi is strongly positive for Alcian blue (pHâ2.5)-periodic acid Schiff (deep violet coloration), and positive with hematoxylin and eosin and with Massonâs trichrome (reddish-brown staining), unlike the MCs of the two species which stain dark red with both Alcian blue (pHâ2.5)-periodic acid Schiff and Massonâs trichrome but respond faintly to hematoxylin and eosin. The differing abundance of MCs in the two lungfishes might reflect different degrees in aerial exposure of the olfactory organ, while the neutral and acid mucopolysaccharide-containing VEC, as indicated by staining properties of the MCs, is evolutionary evidence that P. amphibius and P. dolloi are the closest living relatives to tetrapods, at least in the order Dipnoi.
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