Leonardus is an extinct mammal genus from the Late Cretaceous (Santonian to Maastrichtian) of South America.[ Leonardus at Fossilworks.org] It is a , closely related to the also Late Cretaceous Cronopio and the Miocene Necrolestes.[Guillermo W. Rougier, John R. Wible, Robin M. D. Beck and Sebastian Apesteguía (2012). "The Miocene mammal Necrolestes demonstrates the survival of a Mesozoic nontherian lineage into the late Cenozoic of South America". Proceedings of the National Academy of Sciences of the United States of America. 109 (49): 20053–20058. doi:10.1073/pnas.1212997109.][Alexander O. Averianov, Thomas Martin and Alexey V. Lopatin (2013). "A new phylogeny for basal Trechnotheria and Cladotheria and affinities of South American endemic Late Cretaceous mammals". Naturwissenschaften. 100 (4): 311–326. doi:10.1007/s00114-013-1028-3.]
Description
Leonardus is a fairly small mammal, similar in size to
Necrolestes. It is known from two specimens, the
holotype MACN-RN 172, composed of a left
maxilla, four associated molariform
teeth and two pairs of alveoli, and
MACN-RN 1907, a right mandible with two molariforms. Said molariforms are vaguely peg-like, with a dome-like stylocone.
Discovery
Leonardus is currently only known from the Los Alamitos Formation,
Argentina. The holotype was found in 1990, while the second specimen was described more recently in 2010. The genus name honours the Italian paleontologist Giuseppe Leonardi.
Classification
Leonardus was originally referred to
Dryolestidae, but the lack of a parastylar hook on the molariforms, as well as a few features of the stylocone, suggest that it was grouped with other
and
species at the exclusion of
species, in a clade known as
Meridiolestida.
[Laura Chornogubsky, New remains of the dryolestoid mammal Leonardus cuspidatus from the Los Alamitos Formation (Late Cretaceous, Argentina), Article in Paläontologische Zeitschrift 85(3):343-350 · September 2011
DOI: 10.1007/s12542-010-0095-4] Within Meridiolestida, it consistently groups with
Necrolestes and
Cronopio.
Paleobiology
Leonardus' teeth are noted as being unique among meridiolestids and the animal would have had an orthal and transverse jaw-stroke with tooth-to-tooth shearing,
though no further comments have been made on its diet.
