Astraponotus

Astraponotus Temporal range: Middle-Late Eocene (Mustersan-Tinguirirican) ~48–33.9 Ma PreꞒ Ꞓ O S D C P T J K Pg N
Reconstruction of the skull of Astraponotus, based on Kramarz et al., 2010.
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	†Astrapotheria
Family:	†Astrapotheriidae
Genus:	Astraponotus Ameghino, 1901
Type species
Astraponotus assymmetrum Ameghino, 1901
Species
A. dicksoni Roth, 1903[1] A. dilatatus Roth, 1903 A. holdichi Roth, 1903 A. thompsoni Roth, 1903
Synonyms
Megalophodon Roth 1903 Notamynus Roth 1903

Astraponotus is an extinct genus of astrapotheriids. It lived during the Middle-Late Eocene (in the Mustersan and Tinguirirican of the South American land mammal ages (SALMA), 48-33.9 million years ago) and its fossil remains have been found in the Sarmiento Formation of Argentina, South America.^[2]

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 The nasal bones were quite withdrawn, which suggests the presence of a short proboscis.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 premaxillary and nasal bones, the absence of an antorbital circle, and the reduction of the frontal region. The canines were long and strong, as in all astrapotheres.^[3]

Classification

Astraponotus was first described in 1901 by Florentino Ameghino, based on teeth fossils.^[5] The type species, Astraponotus assymetrum, comes from Eocene terrains known as Gran Barranca, in Patagonia (Argentina). The area was later nicknamed capas Astraponotenses ("Astraponotus' layers" in Spanish) 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 nearly complete skull was not described until 2010, which has allowed hypothesis of the phylogenetic relationships of this animal more precisely.^[3]

The features observed in the teeth of Astraponotus are intermediate between the Middle Eocene astrapotheres and those of the Oligocene-Miocene in the degree of hypsodoncy, the reduced dental formula, and the development of accessory occlusal elements. Moreover, the skull retains plesiomorphic features also observed in the archaic genus Trigonostylops, while the auditory region and the skull base are much closer to those of Parastrapotherium, Astrapotherium, and Granastrapotherium. 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.^[3]

Phylogeny

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

References

External links

• Media related to Astraponotus at Wikimedia Commons

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Genera of South American native ungulates

• Kingdom: Animalia
• Phylum: Chordata
• Class: Mammalia
• Superorder: Laurasiatheria

Xenungulata, Pyrotheria, Astrapotheria, and other minor groups
†Kollpaniidae? Andinodus Molinodus Pucanodus Simoclaenus Tiuclaenus †Didolodontidae Didolodus Enneoconus Ernestokokenia Escribania? Lamegoia Paulogervaisia Raulvaccia Ricardocifellia Saltaodus Umayodus †Xenungulata †Carodniidae Carodnia Etayoa Notoetayoa Rodcania †Pyrotheria †Colombitheriidae Colombitherium Proticia †Pyrotheriidae Baguatherium Berracotherium Carolozittelia Griphodon Propyrotherium Pyrotherium †Astrapotheria Eoastrapostylops †Trigonostylopidae Shecenia Tetragonostylops Trigonostylops †Astrapotheriidae Antarctodon Astrapodon Comahuetherium Liarthrus Maddenia Parastrapotherium †Albertogaudryinae Albertogaudrya Astraponotus †Astrapotheriinae Astrapothericulus Astrapotherium Scaglia †Uruguaytheriinae Granastrapotherium Hilarcotherium Uruguaytherium Xenastrapotherium

Litopterna
†Litopterna †Protolipternidae Asmithwoodwardia Miguelsoria Protolipterna †Amilnedwardsiidae Amilnedwardsia Ernestohaeckelia Rutimeyeria †Sparnotheriodontidae Notiolofos Phoradiadius Sparnotheriodon Victorlemoinea †Indaleciidae Adiantoides Indalecia †Notonychopidae Notonychops Requisia †Lopholipterna †Adianthidae Adianthus Proadiantus Proectocion? Proheptaconus Thadanius Tricoelodus †Macraucheniidae Polymorphis †Cramaucheniinae Caliphrium Coniopternium Cramauchenia Llullataruca Phoenixauchenia Pternoconius Theosodon †Macraucheniinae Cullinia Huayqueriana Macrauchenia Macraucheniopsis Micrauchenia Oxyodontherium Paranauchenia Promacrauchenia Scalabrinitherium Windhausenia Xenorhinotherium †Proterotheriidae Mesolicaphrium Neodolodus Olisanophus Promylophis Pseudobrachytherium †Anisolambdinae Anisolambda Eolicaphrium Guilielmofloweria Heteroglyphis Lambdaconops Paranisolambda Protheosodon †Proterotheriinae Anisolophus Brachytherium Diadiaphorus Diplasiotherium Eoauchenia Epecuenia Epitherium Lambdaconus Neobrachytherium Neolicaphrium Paramacrauchenia Picturotherium Prolicaphrium Proterotherium Tetramerorhinus Thoatheriopsis Thoatherium Uruguayodon Villarroelia †Megadolodinae Bounodus Megadolodus Uncertain placement Kyraodus Proacrodon Salladolodus Xesmodon Wainka

Notoungulata
incertae sedis Acoelodus Archaeogaia Carolodarwinia Perutherium †Notioprogonia Satshatemnus Seudenius †Henricosborniidae Henricosbornia Nanolophodon Othnielmarshia Peripantostylops Simpsonotus †Notostylopidae Boreastylops Chilestylops Edvardotrouessartia Homalostylops Notostylops Otrhonia Parastylops †Toxodontia †Homalodotheriidae Asmodeus Chasicotherium Homalodotherium Trigonolophodon †Isotemnidae Anisotemnus Coelostylodon Distylophorus Hedralophus Isotemnus Lophocoelus Pampatemnus Periphragnis Pleurocoelodon Pleurostylodon Rhyphodon Thomashuxleya †Eutoxodontia †Leontiniidae Anayatherium Ancylocoelus Colpodon Coquenia Elmerriggsia Gualta Henricofilholia Huilatherium Leontinia Martinmiguelia Purperia? Scarrittia Taubatherium Termastherium †Notohippidae Acoelohyrax Argyrohippus Deuterotherium? Edvardocopeia Eomorphippus Eurygenium Mendozahippus Moqueguahippus Morphippus Nesohippus Notohippus Pampahippus Pascualihippus Patagonhippus Perhippidion Plexotemnus Puelia Purperia? Rhynchippus Rosendo Stilhippus Teushentherium Trimerostephanos †Toxodontidae †Nesodontinae Adinotherium Nesodon Proadinotherium †Toxodontinae Abothrodon Andinotoxodon Calchaquitherium Ceratoxodon Charruatoxodon Dinotoxodon Eutomodus Falcontoxodon Gyrinodon Haplodontherium Hemixotodon Hoffstetterius Hyperoxotodon Mesenodon Mesotoxodon Minitoxodon Mixotoxodon Neoadinotherium Neotoxodon Nesodonopsis Nonotherium Ocnerotherium Palyeidodon Paratrigodon Pericotoxodon Piauhytherium Pisanodon Plesiotoxodon Posnanskytherium Prototrigodon Stenotephanos Stereotoxodon Toxodon Toxodontherium Trigodon Trigodonops Xotodon †Typotheria Campanorco Griphotherion †Archaeopithecidae Archaeopithecus Teratopithecus †Oldfieldthomasiidae Allalmeia Brachystephanus Camargomendesia Colbertia Dolichostylodon Itaboraitherium Kibenikhoria Maxschlosseria Oldfieldthomasia Paginula Suniodon Tsamnichoria Ultrapithecus Xenostephanus †Interatheriidae Antofagastia Ignigena Johnbell Munizia Punapithecus †Interatheriinae Archaeophylus Argyrohyrax Boleatherium Brucemacfaddenia Caenophilus Choichephilum Cochilius Eopachyrucos Federicoanaya Interatherium Juchuysillu Miocochilius Neoicochilus Patriarchus Proargyrohyrax Progaleopithecus Protypotherium Santiagorothia †Notopithecinae Antepithecus Guilielmoscottia Notopithecus Transpithecus †Mesotheriidae Fiandraia? Trachytherus †Mesotheriinae Altitypotherium Caraguatypotherium Eotypotherium Eutypotherium Hypsitherium Mesotherium Microtypotherium Plesiotypotherium Pseudotypotherium Rusconitherium Typotheriopsis †Archaeohyracidae Archaeohyrax Archaeotypotherium Bryanpattersonia Eohyrax Pascualhyrax Protarchaeohyrax Pseudhyrax Punahyrax †Hegetotheriidae †Hegetotheriinae Ethegotherium Hegetotheriopsis Hegetotherium Hemihegetotherium Prohegetotherium Pseudohegetotherium Sallatherium †Pachyrukhinae Medistylus Propachyrucos Prosotherium Tremacyllus †Pachyrukhini Pachyrukhos Paedotherium Tremacyllus