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Inproceedings Reference Brain evolution of early placental mammals: the impact of the end-Cretaceous mass extinction on the the neurosensory system of our distant relatives
The end-Cretaceous mass extinction, 66 million years ago, profoundly reshaped the biodiversity of our planet. After likely originating in the Cretaceous, placental mammals (species giving live birth to well-developed young) survived the extinction and quickly diversified in the ensuing Paleocene. Compared to Mesozoic species, extant placentals have advanced neurosensory abilities, enabled by a proportionally large brain with an expanded neocortex. This brain construction was acquired by the Eocene, but its origins, and how its evolution relates to extinction survivorship and recovery, are unclear, because little is known about the neurosensory systems of Paleocene species. We used high-resolution computed tomography (CT) scanning to build digital brain models in 29 extinct placentals (including 23 from the Paleocene). We added these to data from the literature to construct a database of 98 taxa, from the Jurassic to the Eocene, which we assessed in a phylogenetic context. We find that the Phylogenetic Encephalization Quotient (PEQ), a measure of relative brain size, increased in the Cretaceous along branches leading to Placentalia, but then decreased in Paleocene clades (taeniodonts, phenacodontids, pantodonts, periptychids, and arctocyonids). Later, during the Eocene, the PEQ increased independently in all crown groups (e.g., euarchontoglirans and laurasiatherians). The Paleocene decline in PEQ was driven by body mass increasing much more rapidly after the extinction than brain volume. The neocortex remained small, relative to the rest of the brain, in Paleocene taxa and expanded independently in Eocene crown groups. The relative size of the olfactory bulbs, however, remained relatively stable over time, except for a major decrease in Euarchontoglires and some Eocene artiodactyls, while the petrosal lobules (associated with eye movement coordination) decreased in size in Laurasiatheria but increased in Euarchontoglires. Our results indicate that an enlarged, modern-style brain was not instrumental to the survival of placental mammal ancestors at the end-Cretaceous, nor to their radiation in the Paleocene. Instead, opening of new ecological niches post-extinction promoted the diversification of larger body sizes, while brain and neocortex sizes lagged behind. The independent increase in PEQ in Eocene crown groups is related to the expansion of the neocortex, possibly a response to ecological specialization as environments changed, long after the extinction. Funding Sources Marie Sklodowska-Curie Actions, European Research Council Starting Grant, National Science Foundation, Belgian Science Policy Office, DMNS No Walls Community Initiative.
Located in Library / RBINS Staff Publications 2020
Inproceedings Reference Phylogenetic position of Olbitherium (Mammalia, Perissodactyla) based on new material from the early Eocene Wutu Formation
The genus Olbitherium was originally described in 2004 from the early Eocene of the Wutu Formation in China as a ‘perissodactyl-like’ archaic ungulate. Described material of Olbitherium consists of partial dentaries with lower cheek teeth, isolated upper molars, and an isolated upper premolar. Subsequent collaborative fieldwork by Belgian and Chinese researchers discovered new material including a partial skull, the anterior portion of the dentary, and associated postcrania. In their general form, the skull and postcrania are similar to those of early perissodactyls. The new material provides a more complete picture of the upper dentition, and the anterior dentary demonstrates the presence of three lower incisors and a large canine, both ancestral features for perissodactyls. A phylogenetic analysis was conducted to test the affinities of Olbitherium, using a matrix of 321 characters and 72 taxa of placental mammals emphasizing perissodactyls and other ungulates. The results produced four shortest trees of 1981 steps. In all four trees, Olbitherium is the sister-taxon to all perissodactyls except Ghazijhippus. In contrast, when scoring was restricted to the originally described material, the results produced 16 shortest trees of 1970 steps, and Olbitherium nests well within Perissodactyla as sister-taxon to a clade including Lambdotherium and the brontotheriids Eotitanops and Palaeosyops. The new material not only supports the identification of Olbitherium as a perissodactyl, but it also suggests that it is significant for understanding the ancestral perissodactyl morphotype. Funding Sources U.S. National Science Foundation (DEB1456826), Chinese Ministry of Science and Technology (2009DFA32210), and Belgian Science Policy Office (BL/36/C54).
Located in Library / RBINS Staff Publications 2020
Article Reference Identifying Elusive Prehistoric Land Use by Integrating Electromagnetic and Invasive Survey Approaches
Located in Library / RBINS Staff Publications 2021
Article Reference 2500 years of charcoal production in the Low Countries: the chronology and typology of charcoal kilns and their relation with early iron production.
Located in Library / RBINS Staff Publications 2021
Article Reference Early and High Medieval (c. 650 AD - 1250 AD) charcoal production and its impact on woodland composition in the Northwest-European lowland: a study of charcoal pit kilns from Sterrebeek (Central Belgium).
Located in Library / RBINS Staff Publications 2021
Incollection Reference Phylum Annelida. Class Clitellata: Subclass Oligochaeta.
Located in Library / RBINS Staff Publications 2019
Inproceedings Reference From toad to frog: osteological description and taxonomic reattribution of the 'mummified' holotype of Bufo servatus, an Eocene anuran, based on micro-CT examination
The Quercy Phosphorites are a set of Eocene-Oligocene deposits from South-West France that yielded numerous vertebrate fossils, including amphibians, mostly as isolated bones. However, in 1873, several exceptional amphibian specimens were discovered, with the external surface of the unmineralized tissues preserved, and were commonly referred as “mummies”. In the 19th century, they were described without any knowledge of their internal anatomy. Since 2012, we have started scanning these “mummies”, revealing the preserved internal soft tissues and articulated skeleton. A first specimen was attributed in 2013 to Thaumastosaurus gezei and we here present our results from the tomography of a second “mummified” anuran, previously identified as Bufo servatus. The tomography showed a preserved articulated skeleton, and its osteological characteristics are similar to the first scanned anuran “mummy”, representing different ontogenetic stages. Both are now both attributed to Thaumastosaurus servatus nov. comb. The new anatomical information is used to assess the affinities of T. servatus, which appears to belong to the Pyxicephalidae, an African anuran clade. Thaumastosaurus thus represents both the oldest occurrence of this clade in the fossil record and its first occurrence outside of Africa. Its presence in Europe highlights a faunistic exchange with Africa during the Eocene, also documented for several clade of squamates. The presence of this African herpetofauna in Europe might be linked to the warmer climate during the Eocene. However, most of this herpetofauna, including Thaumastosaurus, disappeared from the region around an extinction event (named the “Grande Coupure”) that took place around the Eocene/Oligocene transition (~34 Ma).
Located in Library / RBINS Staff Publications 2021
Article Reference Empidoid flies from Cabo Verde (Diptera, Empidoidea, Dolichopodidade and Hybotidae) are not only composed of Old World tropical species
Located in Library / No RBINS Staff publications
Article Reference Moth flies (Diptera: Psychodidae) from the Belgian transition of the Atlantic to the Central European Faunal zones
Located in Library / No RBINS Staff publications
Article Reference Co-existing species of Drapetis Meigen in Skane (S Sweden) with description of a new species and a key to males of NW European species (Diptera: Hybotidae)
Located in Library / No RBINS Staff publications