title: Ontogenetic and life history trait changes associated with convergent ecological specializations in extinct ungulate mammals.
abstract: Investigating life history traits in mammals is crucial to understand their survival in changing environments. However, these parameters are hard to estimate in a macroevolutionary context. Here we show that the use of dental ontogenetic parameters can provide clues to better understand the adaptive nature of phenotypic traits in extinct species such as South American notoungulates. This recently extinct order of mammals evolved in a context of important geological, climatic, and environmental variations. Interestingly, notoungulates were mostly herbivorous and acquired high-crowned teeth very early in their evolutionary history. We focused on the variations in crown height, dental eruption pattern, and associated body mass of 69 notoungulate taxa, placed in their phylogenetic and geological contexts. We showed that notoungulates evolved higher crowns several times between 45 and 20 Ma, independently of the variation in body mass. Interestingly, the independent acquisitions of ever-growing teeth were systematically accompanied by eruption of molars faster than permanent premolars. These repeated associations of dental innovations have never been documented for other mammals and raise questions on their significance and causal relationships. We suggest that these correlated changes could originate from ontogenetic adjustments favored by structural constraints, and may indicate accelerated life histories. Complementarily, these more durable and efficient dentitions could be selected to cope with important ingestions of abrasive particles in the context of intensified volcanism and increasing aridity. This study demonstrates that assessing both life history and ecological traits allows a better knowledge of the specializations of extinct mammals that evolved under strong environmental constraints.
authors.affiliation: Sorbonne Universités, Centre de Recherche sur la Paléobiodiversité et les Paléoenvironnements, UMR CNRS 7207, CP 38, Muséum National d'Histoire Naturelle, 75005 Paris, France; helder.gomes-rodrigues@mnhn.fr.|Mécanismes Adaptatifs et Evolution, UMR CNRS 7179, Bâtiment Anatomie Comparée, CP 55, Muséum National d'Histoire Naturelle, 75005 Paris, France.
authors.forename: Helder
authors.initials: H
authors.lastname: Gomes Rodrigues
authors.affiliation: Mécanismes Adaptatifs et Evolution, UMR CNRS 7179, Bâtiment Anatomie Comparée, CP 55, Muséum National d'Histoire Naturelle, 75005 Paris, France.
authors.forename: Anthony
authors.identifier: 0000-0003-0991-4434
authors.initials: A
authors.lastname: Herrel
authors.affiliation: Sorbonne Universités, Centre de Recherche sur la Paléobiodiversité et les Paléoenvironnements, UMR CNRS 7207, CP 38, Muséum National d'Histoire Naturelle, 75005 Paris, France.
authors.forename: Guillaume
authors.initials: G
authors.lastname: Billet
mesh_terms: D000220:Adaptation, Biological / Q000502:physiology; D000818:Animals; D057231:Climate Change; D004463:Ecology; D000073566:Eutheria / Q000033:anatomy & histology / Q000145:classification / Q000502:physiology*; D053476:Extinction, Biological; D005580:Fossils / Q000033:anatomy & histology*; D005844:Geology; D060434:Herbivory; D000071421:Life History Traits; D008322:Mammals; D013020:South America; D019228:Tooth Crown / Q000033:anatomy & histology*; D014078:Tooth Eruption
keywords: South America; abrasion; dental ontogeny; hypsodonty; notoungulates