Search

This review deals with recent studies on the lungs of fossil and extant coelacanths with classical techniques (dissections, photonic histology) and modern techniques (SEM, X-ray tomography). This recent knowledge allows to attest the homology between: i) the large bony plates of the calcified organ of extinct coelacanths and the small plates that surround the lung of the extant coelacanth Latimeria; ii) the (supposed functional) lung covered with bony plates of extinct coelacanths and the vestigial (non-functional) lung of the extant coelacanth Latimeria. These results point the fatty organ of Latimeria as probably a mesenteric specialization, questioning its previous attribution to its pulmonary origin.

BrainScapes: The possible landscape of primate brain shapes. The accompanying website of the project liveshere,with videos across the landscape of primate brain shapes,and evolutionary trajectories for thespecies back to the brain of the common ancestor. The shape of primate brains varies widely from small smooth to profusely folded large brains. Studying morphological diversity across phylogeny allows us to better understand how primate brains adapt, and in particular the evolutionary context of the human brain. Recent advances in generative machine learning models have led to algorithms capable of learning shape embeddings and to generate realistic new instances. We explored an autoencoder deep neural network to generate shapes of primate brains including 34 different species.Our network successfully learnt a landscape of changes in shape. Interestingly, species with brains of comparable volume were close in the learnt space, despite having been size-normalised for the training. This suggests that changes in volume are consistently concomitant with changes in shape, and this disregarding the species’ position in the phylogenetic tree.Our network is also able to generate new data. We generated possible brain shapes for all ancestral states of the primate phylogenetic tree, and evolutionary trajectories for each of our species back to the brain of the common ancestor. In conclusion, we successfully trained a deep neural network to learn the space of morphological variation across primates, and to generate new data along the phylogenetic tree. We obtained evolutionary trajectories of extant primate brains all the way back to the common ancestor. &nbsp

Les restes humains sont présents dans les collections du Muséum national d’histoire naturelle de Paris depuis sa création. Depuis toujours, ces pièces ont constitué un support pour l’enseignement, un matériel essentiel pour la recherche et, bien sûr, des pièces incontournables dans les présentations muséales. Par conséquent, une attention particulière doit être portée à ces collections, le bien-fondé d’une collection étant qu’elle doit servir pour être pleinement valorisée. Human remains have been part of the collections of the Muséum National d’Histoire Naturelle, Paris, since it was founded. These items have always been used for teaching purposes, provided basic material for research, and, of course, been put on display in the museum. Consequently, particular attention must be paid to these collections, the legitimacy of a collection being that its potential should be fully exploited.

Lungs are specialized organs that originated from the posterior pharyngeal cavity and considered as plesiomorphic for osteichthyans, as they are found in extant basal actinopterygians (i.e. Polypterus) and in all major groups of extant sarcopterygians. The presence of a vestigial lung in adult stages of the extant coelacanth Latimeria chalumnae is the result of allometric growth during ontogeny, in relation with deep times adaptation to deep water. Here, we present the first detailed histological and anatomical description of the lung of Latimeria chalumnae, providing new insights into its arrested differentiation in an air-breathing complex, mainly represented by the absence of pneumocytes and of compartmentalization in the latest ontogenetic stages.

International audience