Digital methodologies for rendering the gross morphology of the brain from X-ray computed tomography data have expanded our current understanding of the origin and evolution of avian neuroanatomy and provided new perspectives on the cognition and behavior of birds in deep time. However, fossil skulls germane to extracting digital endocasts from early stem members of extant avian lineages remain exceptionally rare. Data from early-diverging species of major avian subclades provide key information on ancestral morphologies in Aves and shifts in gross neuroanatomical structure that have occurred within those groups. Here we describe data on the gross morphology of the brain from a mid-to-late Paleocene penguin fossil from New Zealand. This most basal and geochronologically earliest-described endocast from the penguin clade indicates that described neuroanatomical features of early stem penguins, such as lower telencephalic lateral expansion, a relatively wider cerebellum, and lack of cerebellar folding, were present far earlier in penguin history than previously inferred. Limited dorsal expansion of the wulst in the new fossil is a feature seen in outgroup waterbird taxa such as Gaviidae (Loons) and diving Procellariiformes (Shearwaters, Diving Petrels, and allies), indicating that loss of flight may not drastically affect neuroanatomy in diving taxa. Wulst enlargement in the penguin lineage is first seen in the late Eocene, at least 25 million years after loss of flight and cooption of the flight stroke for aquatic diving. Similar to the origin of avian flight, major shifts in gross brain morphology follow, but do not appear to evolve quickly after, acquisition of a novel locomotor mode. Enlargement of the wulst shows a complex pattern across waterbirds, and may be linked to sensory modifications related to prey choice and foraging strategy.
High disparity among avian forelimb and hind limb segments in crown birds relative to non-avialan theropod dinosaurs, potentially driven by the origin of separate forelimb and hind limb locomotor modules, has been linked to the evolution of diverse avian locomotor behaviors. However, this hypothesized relationship has rarely been quantitatively investigated in a phylogenetic framework. We assessed the relationship between the evolution of limb morphology and locomotor behavior by comparing a numerical proxy for locomotor disparity to morphospace sizes derived from a dataset of 1,241 extant species. We then estimated how limb disparity accumulated during the crown avian radiation. Lastly, we tested whether limb segments evolved independently between each limb module using phylogenetically informed regressions. Hind limb disparity increased significantly with locomotor disparity after accounting for clade age and species richness. We found that forelimb disparity accumulated rapidly early in avian evolution, whereas hind limb disparity accumulated later, in more recent divergences. We recovered little support for strong correlations between forelimb and hind limb morphology. We posit that these findings support independent evolution of locomotor modules that enabled the striking morphological and behavioral disparity of extant birds.
The middle–late Eocene of Antarctica was characterized by dramatic change as the continent became isolated from the other southern landmasses and the Antarctic Circumpolar Current formed. These events were crucial to the formation of the permanent Antarctic ice cap, affecting both regional and global climate change. Our best insight into how life in the high latitudes responded to this climatic shift is provided by the fossil record from Seymour Island, near the eastern coast of the Antarctic Peninsula. While extensive collections have been made from the La Meseta and Submeseta formations of this island, few avian taxa other than penguins have been described and mammalian postcranial remains have been scarce. Here, we report new fossils from Seymour Island collected by the Antarctic Peninsula Paleontology Project. These include a mammalian metapodial referred to Xenarthra and avian material including a partial tarsometatarsus referred to Gruiformes (cranes, rails, and allies). Penguin fossils (Sphenisciformes) continue to be most abundant in new collections from these deposits. We report several penguin remains including a large spear-like mandible preserving the symphysis, a nearly complete tarsometatarsus with similarities to the large penguin clade Palaeeudyptes but possibly representing a new species, and two small partial tarsometatarsi belonging to the genus Delphinornis. These findings expand our view of Eocene vertebrate faunas on Antarctica. Specifically, the new remains referred to Gruiformes and Xenarthra provide support for previously proposed, but contentious, earliest occurrence records of these clades on the continent.
Background Numerous medical education training programs are currently implemented internationally to train residents and future academic physicians for teaching duties, many of which use peer‐teaching in anatomy as a major component. The length of these programs and the degree to which they provide both teaching practice and generalized training in medical educational competencies varies widely. Conversely, teacher training programs aimed at anatomy graduate students have a robust balance of in‐class practice and out‐of‐class professional development but take place over a longer timescale. With unscheduled curricular time at a premium in most medical programs, developing comprehensive training courses that can be administered over an accelerated timescale and provide generalizable professional skills in medical education is essential. Intervention In summer of 2021 I implemented a 6‐week pilot program for developing practical teaching and medical education skills in undergraduate medical students. The program consisted of an in‐class component where students performed daily peer teaching in a summer graduate‐level anatomy course and out‐of‐class professional development including training on educational methods, peer evaluations of student‐made materials, and reflective exercises. Assessment 5 students were enrolled in the pilot program, 3 of which completed a 1‐5 Likert Scale, IRB‐approved survey after completion. The 22‐question survey measured pre‐and‐post program perceived confidence in 4 skill categories: anatomy knowledge (4 questions), teaching and assessment (5 questions), communication (9 questions), and educational research and innovation (4 questions). Although current survey sample lacks enough statistical power for formal nonparametric tests, initial student responses indicate improved self‐reported confidence in all 4 areas. Educational research and innovation showed the highest average increase (+2.4), followed by teaching and assessment (+2) anatomy knowledge (+1.58) and communication (+1.47). Significance & Conclusion With the caveat that limited data are available, students’ perceived confidence increased in all skill areas following participation in the training program. Additional longitudinal follow up will be needed to further determine the utility derived from the course pre‐and‐post residency. If successful, this course may serve as a model for both medical student and anatomical educator training courses that can be deployed on shorter timescales.
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