Leonardus

Leonardus is an extinct mammal genus from the Late Cretaceous (Late Santonian to Maastrichtian) of South America.[1] It is a meridiolestidan dryolestoid, closely related to the also Late Cretaceous Cronopio and the Miocene Necrolestes.[2][3]

This article is about the fossil mammalian genus. For the given name, see Leonardus (name).

Leonardus
Temporal range: Late Santonian-Maastrichtian
~84–66 Ma
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Superorder: †Dryolestoidea
Order: †Dryolestida
Clade: †Meridiolestida
Family: †Leonardus
Bonaparte 1990
Type species
Leonardus cuspidatus
Bonaparte 1990

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.

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 South American and African dryolestoids at the exclusion of Laurasian species, in a clade known as Meridiolestida.[4] Within Meridiolestida, it consistently groups with Necrolestes and Cronopio.[2][3]

Paleobiology

Leonardus' teeth are noted as being unique among dryolestids and the animal would have had an orthal and transverse jaw-stroke with tooth-to-tooth shearing,[4] though no further comments have been made on its diet.

References
  1. Leonardus at Fossilworks.org
  2. 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.
  3. 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.
  4. 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
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