''Astraponotus'' is an extinct

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

of astrapotheriids. It lived during the Middle-Late Eocene (in the

Mustersan The Mustersan age is a period of geologic time (48.0–42.0 Ma) within the Eocene epoch of the Paleogene, used more specifically within the South American land mammal age (SALMA) classification. It follows the Casamayoran and precedes the Divisade ...

and

Tinguirirican The Tinguirirican ( es, Tinguiririquense) age is a period of geologic time (36.0–29.0 Ma) within the Late Eocene and Early Oligocene epochs of the Paleogene, used more specifically within the SALMA classification in South America. It follows th ...

of the

South American land mammal age The South American land mammal ages (SALMA) establish a geologic timescale for prehistoric South American fauna beginning 64.5 Mya (unit), Ma during the Paleocene and continuing through to the Late Pleistocene (0.011 Ma). These periods are referre ...

s (SALMA), 48-33.9 million years ago) and its fossil remains have been found in the

Sarmiento Formation The Sarmiento Formation (Spanish: ''Formación Sarmiento''), in older literature described as the Casamayor Formation, is a geological formation in Chubut Province, Argentina, in central Patagonia, which spans around 30 million years from the mid- ...

Argentina Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, th ...

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the southe ...

.''Astraponotus''
at

Fossilworks Fossilworks is a portal which provides query, download, and analysis tools to facilitate access to the Paleobiology Database The Paleobiology Database is an online resource for information on the distribution and classification of fossil animals ...

.org

Description

Unlike most astrapotheres, ''Astraponotus'' was equipped with an unusually high, short, narrow skull. The nasal bones were quite withdrawn, which suggests the presence of a short proboscis. Other unusual features of ''Astraponotus'' includes the extreme reduction of the

premaxilla The premaxilla (or praemaxilla) is one of a pair of small cranial bones at the very tip of the upper jaw of many animals, usually, but not always, bearing teeth. In humans, they are fused with the maxilla. The "premaxilla" of therian mammal has b ...

ry and

nasal bone The nasal bones are two small oblong bones, varying in size and form in different individuals; they are placed side by side at the middle and upper part of the face and by their junction, form the bridge of the upper one third of the nose. Eac ...

s, the absence of an antorbital circle, and the reduction of the frontal region. The

canines Canine may refer to: Zoology and anatomy * a dog-like Canid animal in the subfamily Caninae ** ''Canis'', a genus including dogs, wolves, coyotes, and jackals ** Dog, the domestic dog * Canine tooth, in mammalian oral anatomy People with the surn ...

were long and strong, as in all astrapotheres.Kramarz, A. G., Bond M. and Forasiepi, A. M., 2010. New remains of ''Astraponotus'' (Mammalia, Astrapotheria) and considerations on Astrapothere cranial evolution. ''Paläontol Z''. DOI 10.1007/s12542-010-0087-4.

Classification

''Astraponotus'' was first described in 1901 by

Florentino Ameghino Florentino Ameghino (born Giovanni Battista Fiorino Giuseppe Ameghino September 19, 1853 – August 6, 1911) was an Argentine naturalist, paleontologist, anthropologist and zoologist, whose fossil discoveries on the Argentine Pampas, especially ...

, based on teeth fossils.F. Ameghino. 1901. Notices préliminaires sur des ongulés nouveaux des terrains crétacés de Patagonie reliminary notes on new ungulates from the Cretaceous terrains of Patagonia ''Boletin de la Academia Nacional de Ciencias de Córdoba'' 16:349-429 The

type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specimen ...

, ''Astraponotus assymetrum'', comes from Eocene terrains known as Gran Barranca, in

Patagonia Patagonia () refers to a geographical region that encompasses the southern end of South America, governed by Argentina and Chile. The region comprises the southern section of the Andes Mountains with lakes, fjords, temperate rainforests, and gl ...

(

). The area was later was nicknamed ''capas Astraponotenses'' ("''Astraponotus layers" in

Spanish Spanish might refer to: * Items from or related to Spain: **Spaniards are a nation and ethnic group indigenous to Spain **Spanish language, spoken in Spain and many Latin American countries **Spanish cuisine Other places * Spanish, Ontario, Cana ...

) due to the abundance of the peculiar fossils of this animal. Other species were described later (for example, ''A. dicksoni'' and ''A. holdichi''), but always based just on the remains of the teeth and jaws. A a nearly complete skull was not described until 2010, which has allowed hypothesis of the

phylogenetic In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...

relationships of this animal more precisely. The features observed in the teeth of ''Astraponotus'' are intermediate between the

Middle Eocene The Eocene ( ) Epoch is a geological epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period in the modern Cenozoic Era. The name ''Eocene'' comes from the Ancient Greek (''ēṓs'', "dawn ...

astrapotheres and those of the

Oligocene The Oligocene ( ) is a geologic epoch of the Paleogene Period and extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that define the epoch are well identified but the ...

Miocene The Miocene ( ) is the first geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and means "less recen ...

in the degree of hypsodoncy, the reduced

dental formula Dentition pertains to the development of teeth and their arrangement in the mouth. In particular, it is the characteristic arrangement, kind, and number of teeth in a given species at a given age. That is, the number, type, and morpho-physiolo ...

, and the development of accessory occlusal elements. Moreover, the skull retains

plesiomorphic In phylogenetics, a plesiomorphy ("near form") and symplesiomorphy are synonyms for an ancestral character shared by all members of a clade, which does not distinguish the clade from other clades. Plesiomorphy, symplesiomorphy, apomorphy, and ...

features also observed in the archaic genus ''

Trigonostylops ''Trigonostylops'' is an extinct genus of South American meridiungulatan ungulate, from the Late Paleocene to Late Eocene (Itaboraian to Tinguirirican in the SALMA classification) of South America (Argentina and Peru) and Antarctica (Seymour Isla ...

'', while the auditory region and the skull base are much closer to those of ''

Parastrapotherium ''Parastrapotherium'' is an extinct genus of South American land mammal that existed from the Late Oligocene (Deseadan SALMA) to the Early Miocene (Colhuehuapian SALMA). The genus includes some of the largest and smallest known astrapotherian, bu ...

'', ''

Astrapotherium ''Astrapotherium'' ("lightning beast") is an extinct genus of South American mammals that vaguely resembled a small elephant or large tapir. However, it was unrelated to elephants or tapirs, but was instead related to other extinct South American ...

'', and ''

Granastrapotherium ''Granastrapotherium'' is an extinct genus of ungulate mammals, described from remains found in rocks of the Honda Group in the Tatacoa Desert, in the Colombian departments of Huila and Tolima, at the Miocene fossil site La Venta. The only spec ...

''. Furthermore, the ''Astraponotus'' skull differs from all astrapotheres known in its disproportionate height, the narrowness of the skull, and other numerous cranial specializations that are opposite to ''Astrapotherium''. These features seem surprisingly derived for an Eocene astrapothere, and suggest that these extreme cranial specializations were developed independently during the evolution of this order; ''Astraponotus'' could represent a lineage distinct from ''Astrapotherium'' and other Miocene forms.

Phylogeny

Cladogram A cladogram (from Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an evolutionary tree because it does not show how ancestors are related to d ...

based in the

phylogenetic analysis In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...

by Vallejo-Pareja ''et al''., 2015, showing the position of ''Astraponotus'':

References

External links

* {{Taxonbar, from=Q18416301 Meridiungulata Eocene mammals of South America Tinguirirican Divisaderan Mustersan Paleogene Argentina Fossils of Argentina Fossil taxa described in 1901 Taxa named by Florentino Ameghino Prehistoric placental genera Golfo San Jorge Basin Sarmiento Formation