Some recent non-dino papers not yet mentioned:
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Brochuchus parvidens sp. nov.
Adam P. Cossette, Amanda J. Adams, Stephanie K. Drumheller, Jennifer H. Nestler, Brenda R. Benefit, Monte L. McCrossin, Frederick K. Manthi, Rose Nyaboke Juma and Christopher A. Brochu (2020)
A new crocodylid from the middle Miocene of Kenya and the timing of crocodylian faunal change in the late Cenozoic of Africa.
Journal of Paleontology (advance online publication)
DOI:
https://doi.org/10.1017/jpa.2020.60 https://www.cambridge.org/core/journals/journal-of-paleontology/article/new-crocodylid-from-the-middle-miocene-of-kenya-and-the-timing-of-crocodylian-faunal-change-in-the-late-cenozoic-of-africa/8E6621CE1E07FE61A3E9AA855736C5C7UUID:
http://zoobank.org/e6f0b219-5f3e-44e5-bdb9-60a4fae8d126Brochuchus is a small crocodylid originally based on specimens from the early Miocene of Rusinga Island, Lake Victoria, Kenya. Here, we report occurrences of Brochuchus from several early and middle Miocene sites. Some are from the Lake Victoria region, and others are in the Lake Turkana Basin. Specimens from the middle Miocene Maboko locality form the basis of a new species, Brochuchus parvidens, which has comparatively smaller maxillary alveoli. Because of the smaller alveoli, the teeth appear to be more widely spaced in the new species. We also provide a revised diagnosis for Brochuchus and its type species, B. pigotti. A phylogenetic analysis supports a close relationship between Brochuchus and tube-snouted Euthecodon, but although relationships among crocodylids appear poorly resolved in the set of optimal trees, this is because Brochuchus and Euthecodon, along with early Miocene "Crocodylusâ gariepensis from the early Miocene of Namibia, jointly adopt two distinct positions--either closely related to the living sharp-nosed crocodile (Mecistops) or to a group including the living dwarf crocodiles (Osteolaemus). Character support for a close relationship with Mecistops is problematic, and we suspect a closer relationship to Osteolaemus will be recovered with improved sampling, but the results here are ambiguous. In either case, Brochuchus is more closely related to living groups not currently found in East Africa. This material helps constrain the timing of crocodylian faunal turnover in the East African Rift Valley System, with endemic lineages largely being replaced by Crocodylus in the middle or late Miocene possibly in response to regional xerification and the replacement of continuous rainforest cover with open grasslands and savannas.
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Levi Storks, Brian J Powell & Manuel Leal (2020)
Peeking inside the lizard brain: Neuron numbers in Anolis and its implications for cognitive performance and vertebrate brain evolution.
Integrative and Comparative Biology, icaa129 (advance online publication)
doi:
https://doi.org/10.1093/icb/icaa129https://academic.oup.com/icb/advance-article-abstract/doi/10.1093/icb/icaa129/5903742Studies of vertebrate brain evolution have mainly focused on measures of brain size, particularly relative mass and its allometric scaling across lineages, commonly with the goal of identifying the substrates that underly differences in cognition. However, recent studies on birds and mammals have demonstrated that brain size is an imperfect proxy for neuronal parameters that underlie function, such as the number of neurons that make up a given brain region. Here we present estimates of neuron numbers and density in two species of lizard, Anolis cristatellus and A. evermanni, representing the first such data from squamate species, and explore its implications for differences in cognitive performance and vertebrate brain evolution. The isotropic fractionator protocol outlined in this paper is optimized for the unique challenges that arise when using this technique with lineages having nucleated erythrocytes and relatively small brains. The number and density of neurons and other cells we find in Anolis for the telencephalon, cerebellum, and the rest of the brain (ROB) follow similar patterns as published data from other vertebrate species. Anolis cristatellus and A. evermanni exhibited differences in their performance in a motor task frequently used to evaluate behavioral flexibility, which was not mirrored by differences in the number, density, or proportion of neurons in either the cerebellum, telencephalon or ROB. However, the brain of A. evermanni had a significantly higher number of nonneurons and a higher nonneuron to neuron ratio across the whole brain, which could contribute to the observed differences in problem solving between A. cristatellus and A. evermanni. Although limited to two species, our findings suggest that neuron number and density in lizard brains scale similarly to endothermic vertebrates in contrast to the differences observed in brain to body mass relationships. Data from a wider range of species is necessary before we can fully understand vertebrate brain evolution at the neuronal level.
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Free pdf:
Inhibitory control, the inhibition of prepotent actions, is essential for higher-order cognitive processes such as planning, reasoning, and self-regulation. Individuals and species differ in inhibitory control. Identifying what influences inhibitory control ability within and between species is key to understanding how it evolved. We compared performance in the cylinder task across five lizard species: tree skinks (Egernia striolata), gidgee skinks (Egernia stokesii), eastern blue-tongue skinks (Tiliqua s. scincoides), sleepy lizards (Tiliqua r. asper), and eastern water skinks (Eulamprus quoyii). In our task, animals had to inhibit the prepotent motor response of directly approaching a reward placed within a semi-transparent mesh cylinder and instead reach in through the side openings. Additionally, in three lizard species, we compared performance in the cylinder task to reversal learning to determine the task specificity of inhibitory ability. Within species, neither sex, origin, body condition, neophobia, nor pre-experience with other cognitive tests affected individual performance. Species differed in motor response inhibition: Blue-tongue skinks made fewer contacts with the semi-transparent cylinder wall than all other species. Blue-tongue skinks also had lower body condition than the other species which suggest motivation as the underlying cause for species differences in task performance. Moreover, we found no correlation between inhibitory ability across different experiments. This is the first study comparing cylinder task performance among lizard species. Given that inhibitory control is probably widespread in lizards, motor response inhibition as exercised in the cylinder task appears to have a long evolutionary history and is likely fundamental to survival and fitness.
Significance
The study of lizard cognition is receiving increasing attention. Lizards are a diverse group with a wide range of ecological attributes and represent a model system through which we can test a wide range of hypotheses relating to cognitive evolution. Furthermore, considering their evolutionary history, studying non-avian reptile cognition can help understand the evolution of different cognitive abilities including inhibitory control. Here, we provide a comparison of inhibitory control ability in five lizard species. Consequently, we are able to, firstly, validate a method (the cylinder task) initially developed for the use in mammals and birds, for use in lizards, and secondly, collect valuable data on inhibitory control in a poorly studied group with respect to cognitive ability. Our study suggests non-cognitive factors as a major influence on cylinder task performance, which is in agreement with previous studies of other vertebrates.
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Free pdf:
Free pdf:
http://njg.geologi.no/images/NJG_articles/Herron_et_al._accepted_manuscript.pdfThe Late Carboniferous was a crucial interval for the establishment of terrestrial ecosystems. A dramatic change in tetrapod distribution and ecology is coupled with an ongoing transition from amphibian to amniote domination. Presented here is a new set of tetrapod footprints from a single slab discovered on the island of BjÃrnÃya in the Norwegian High Arctic. A three-dimensional photogrammetric model was constructed to allow analysis of the trackway, and palaeoenvironmental observations were taken to provide context to the ichnological determinations. The slab appears to preserve the transition from swimming to walking. Statistical tests provide indication that there is a significant change in locomotive behaviour (swimming to walking) present on the slab (p = 0.0026, n = 15). This coincides with a change in the preservation style and an apparent change in the depth of water traversed by the tracemaker. Two trackways can be assigned to the ichnogenus Limnopus Marsh, 1894 (temnospondyl amphibians). They consist of 36 and 24 prints, respectively, and have widths and lengths of 151 mm x 2149 mm and 166 mm x 1226 mm. Two other trackways represent the traces of indeterminate tetrapods. Palaeoenvironmental analysis suggests that the trackways had lain in a fluvial floodplain setting in a palaeo-river valley system, in agreement with regional-scale analyses. Locomotion analysis suggests that on moving from submerged walking and swimming to terrestrial walking, this large Late Carboniferous temnospondyl increased its pace angulation and lengthened its stride. At ~30ÂN, these tracks may be the farthest north Limnopus trackways yet found in terms of palaeolatitude. They are the first Carboniferous tetrapod traces discovered from Svalbard and are probably among the oldest examples of Limnopus yet found.