Astrapotherium

Astrapotherium ("lightning beast") is an extinct genus of large astrapotherian ungulate native to South America during the early-middle Miocene. It is the best known member of the group. The type species. A. magnus have been found in the Santa Cruz Formation in Argentina. Other fossils have been found in the Deseado, Sarmiento, and Aisol Formations of Argentina and Chile (Cura-Mallín Group).^[2]

Astrapotherium Temporal range: Early Miocene–Middle Miocene PreꞒ Ꞓ O S D C P T J K Pg N
Skull of Astrapotherium magnum
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	†Astrapotheria
Family:	†Astrapotheriidae
Subfamily:	†Astrapotheriinae
Genus:	†Astrapotherium Burmeister, 1879
Type species
†Astrapotherium magnum Owen, 1853
Species
†A. burmeisteri Mercerat, 1891 †A. guillei Kramarz et al. 2019[1] †A. magnum Owen, 1853 †A. ruderarium Ameghino, 1902
Synonyms
Genus synonymy Listriotherium Mercerat 1891 Mesembriotherium Moreno 1882 Xylotherium Mercerat 1891 Synonyms of A. burmeisteri Astrapotherium giganteum Ameghino, 1891 Astrapotherium delimitatum Ameghino, 1891 Synonyms of A. magnum Astrapotherium columnatum Ameghino, 1891 Astrapotherium nanum Ameghino, 1891 Astrapotherium karaikense Ameghino, 1904b Astrapodon carinatus Ameghino, 1891 Synonyms of A. ruderarium Parastrapotherium paucum Ameghino 1902 Parastrapotherium crassum (partim) Ameghino 1902 Astrapothericulus minusculus Ameghino 1902 Astrapothericulus laevisculus Ameghino 1902 Astrapotherium triangulidens Ameghino 1902 Prochalicotherium patagonicum Ameghino 1902

Description

Restoration and size comparison of A. magnus

Astrapotherium had an elongated body, with a total length around 2.5 m (8.2 ft), a weight of nearly 1,000 kg (2,200 lb), and relatively short limbs.^[3] Larger estimates suggest its body mass was up to 1,600–3,500 kilograms (3,500–7,700 lb).^[4] It had small plantigrade feet, and the hind limbs were significantly weaker than the fore limbs. Its four canine teeth were elongated to form short tusks, and it had broad, protruding lower incisors, which likely ground against a horny pad in the upper jaw, as in many modern ruminants.^[3]

Canine tooth of A. magnus at the Museum für Naturkunde, Berlin

Astrapotherium has been inferred to have had a tapir-like proboscis, based on its retracted narials and short upper jaw.^[5]

Classification

Cladogram based in the phylogenetic analysis published by Vallejo-Pareja et al., 2015, showing the position of Astrapotherium:^[6]

	Eoastrapostylops
	Trigonostylops Tetragonostylops Albertogaudrya Scaglia Astraponotus Maddenia Comahuetherium Parastrapotherium Astrapotheriinae Astrapotherium Astrapothericulus Uruguaytheriinae Uruguaytherium Hilarcotherium Xenastrapotherium Granastrapotherium

Paleobiology

The animal was probably at least partially aquatic, living in shallow water in a similar manner to a modern hippopotamus.^[3]