Notoungulata

Hegetotheriidae

Hegetotheriidae

Hegetotheriids (also known as hegetotheres) were small to medium-sized mammals that ranged from the size of a rabbit (probably about 12-16″/30-40 cm ) to a beaver (about 3 feet/1 m long). Some hegetotheres were very rabbit-like in both their skull and skeleton (pachyrukhines; see below), whereas others had proportions more similar to a large rodent such […]

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Basal typotheres (Oldfieldthomasiidae, Archaeopithecidae)

Basal typotheres (Oldfieldthomasiidae, Archaeopithecidae)

The evolutionary relationships of most notoungulates are not entirely clear. This is particularly true for notoungulates that diverged prior to the split between typotheres and toxodonts (basal notoungulates) and early members of the Typotheria (basal typotheres). Basal typotheres are generally placed in the families Oldfieldthomasiidae and Archaeopithecidae, but although some phylogenetic analysis have found these to be […]

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Notoungulata

Notoungulata

Notoungulates –  literally “southern ungulates.” – may be the most emblematic of all extinct South American mammals. Notoungulates were the most abundant of the native South American ungulates, and probably more species of notoungulates have been named than all other groups of endemic ungulates combined. The group includes more than 150 extinct genera in around a dozen families. Notoungulates lived […]

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Basal Notoungulates (Henricosborniidae, Notostylopidae)

Basal Notoungulates (Henricosborniidae, Notostylopidae)

The basal notoungulate families Henricosborniidae and Notostylopidae are mainly known from Eocene fossil sites. Henricosborniids have also been identified from at least one Paleocene site (Tiupampa), and notostylopids survived into the early Oligocene based on a recently named species from Chile, Chilestylops davidsoni (Bradham et al. 2015). The cheek teeth of notostylopids are rather distinctive (see Simpson 1948 for […]

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Mesotheriidae

Mesotheriidae

Mesotheriids, more commonly known as mesotheres, have been known to science longer than almost any other group of notoungulates. The first mesotheriid, Mesotherium, was named by Serres in 1867. At that time, only the toxodontids Toxodon and Nesodon had been named and described. Mesotherium was named “middle beast” in reference to Serres’ belief that it represented an evolutionary intermediate […]

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Interatheriidae

Interatheriidae

The Interatheriidae (interatheres) are perhaps the most successful group of notoungulates; they are the longest-ranging of all notoungulate families, and nearly two dozen genera have been described (though it is unclear how many of these are valid). Moreover, interatheriids are often very abundant in the faunas in which they are found, suggesting high population densities; […]

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Archaeohyracidae

Archaeohyracidae

Archaeohyracids (“ancient hyraxes”) are in no way related to true hyraxes (order Hyracoidea), nor do they closely resemble them. They have traditionally been one of the most poorly known groups of  notoungulates; they tend to be rare in most faunas, and only a single skull (the holotype of Archaeohyrax patagonicus, at left) had been described until […]

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Hegetotheriidae

Hegetotheriidae

Coming Soon. Classification: Order Notoungulata; Suborder Typotheria Stratigraphic Range: early Oligocene (Tinguirirican) to early Pleistocene (Marplatan) Selected Genera: Hegetotherium, Hemihegetotherium, Paedotherium, Prohegetotherium, Propachyrucos, Pachyrukhos, Tremacyllus  Selected References: Cerdeño, E., and M. Bond. 1998. Taxonomic revision and phylogeny of Paedotherium and Tremacyllus (Pachyrukhinae, Hegetotheriidae, Notoungulata) from the late Miocene to Pleistocene of Argentina. Journal of Vertebrate […]

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Toxodontidae

Toxodontidae

Coming Soon. Classification: Order Notoungulata; Suborder Toxodontia Stratigraphic Range: Selected Genera: Selected References:

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Isotemnidae

Isotemnidae

Coming Soon. Classification: Order Notoungulata; Suborder Toxodontia Stratigraphic Range: Selected Genera: Selected References:

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