Lionel Hautier Department of Zoology Cambridge

My research entailed the use of paleontological, developmental, and morphometrical data to consider recent phylogenetical results. Parallelisms and convergences are widely recognized in the evolutionary history of mammals. Part of these homoplasies has been primarily highlighted by paleontological data, which provide a temporal framework and unusual combinations of characters not found in modern forms. Although the skull anatomy and the organisation of the masticatory apparatus were early recognized and used as diagnostic phylogenetical attributes, many difficulties occurred in the interpretation of the evolutionary history and systematics of mammals.

Lionel

Lionel Hautier Department of Zoology Cambridge

Placental mammals are an extraordinarily successful radiation, derived from a single common ancestor that lived approximately 125 million years ago. The anatomy and developmental biology of this common ancestor are central to understanding the success of this radiation. The recent recognition of afrotherians and xenarthrans as basal mammals indicates that developmental and morphological study of these groups provides important data that has been overlooked hitherto. I have previously focused on morphological diversity in rodents, but I am actually interested in xenartrans and afrotherians evolution and development. Because biological shapes are often complex and evolve depending on several internal constraints, they must be assessed using integrative methods (i.e. anatomical, morphometrical, and ontogenetical data).

My ongoing research focuses on:

•Investigating skeleto-dental development in afrotherian and xenarthran mammals to test an hypothetic departure of southern placentals from the patterns seen in other mammals. This will in turn lead to the capacity to document connections between genotype and phenotype.
•Testing the role of selection characterizing similar morphological evolutions toward news habitats and diet between different clades of extant and extinct mammals (i.e. Rodentia, Afrotheria, and Xenarthra).
•Assessing the evolution of the zygomasseteric construction of both extinct and extant mammals in using morphological (osteological and myological), morphometrical, and palaeontological évidence.

The study of major morphological transformations in mammals has provided classic examples of the integration of developmental with palaeontological data. Given my background, I am convinced that a precise comparison of developmental and paleontological data can provide new and productive ways to understand morphological evolution in deep time.

HAUTIER

Among mammals, the radiation of rodents represents a special case. They constitute roughly half of the current mammalian diversity and are considered to be one of the great success stories of mammal evolutionary history. While exceptional for an intense diversification of lineages, the evolutionary history of the order Rodentia comprises only a small number of morphotypes for the skull and mandible. I showed that potential phylogenetic information can derive from morphological characteristics of zygomasseteric architecture in rodents insofar as detailed evolutionary interpretation of functional aspects of their cranial structure is conducted and compared with fossil evidence.