Eritherium

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Eritherium
Temporal range: Selandian, 60  Ma
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Eritherium azzouzorum 54.JPG
Jaw of Eritherium azzouzorum
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Proboscidea
Genus: Eritherium
Gheerbrant, 2009
Species:
E. azzouzorum
Binomial name
Eritherium azzouzorum
Gheerbrant, 2009

Eritherium is an extinct genus of early Proboscidea found in the Ouled Abdoun basin (early Thanetian age), Morocco. It lived about 60 million years ago. It was first named by Emmanuel Gheerbrant in 2009 and the type species is Eritherium azzouzorum. Eritherium is the oldest, smallest and most primitive known elephant relative.

Contents

Description

The holotype (specimen number MNHN PM69) is now in the Musée d'histoire naturelle - Guimet in Lyon and includes an upper jaw (with approaches of the zygomatic bone and two maxillary branches, each of the two posterior premolars (P3 and 4) and three molars (M1-3)). The piece is about 6 inches long, 5 inches wide and just over 3 inches high. In addition, the fossils include 15 more objects including the skull bones (frontal and nasal bones), lower jaw fragments and teeth and the upper and lower jaw. [1] It was about 20 cm tall at the shoulder and weighed about 5–6 kg. [2]

Generally, Eritherium shared similarities in the structure of their teeth with other Paenungulata such as the extinct Embrithopoda or early representatives of the manatees, but their teeth are more specialised. The dentition of the mandible that was reconstructed (from two left fragments) made up the complete sequence of the original teeth of mammals: with three incisors, one canine, four premolars and three molars. The tooth row was closed and had no diastema between the canine tooth on the front and back teeth. This primitive mammalian dentition is unique among Proboscideans.

The molars were generally bunodont (i.e. with small enamel cusps on the occlusal surface-bearing structure). Between these bumps were approaches for forming transverse strips on the first two molars and on the rearmost molar, which is typical in lophodont teeth. The premolars had only one (lower jaw) or two (in the maxilla) cusps. The first incisor is relatively large and asymmetric and already showed signs of reduction. These facts link Eritherium with other early Proboscideans. Another primitive characteristic is the short symphysis of the mandible.

The reconstruction of the upper portion of the skull showed that the eye socket was relatively far forward in the skull. Most other early Paenungulata had an orbit significantly shifted to the rear position of the skull.

Systematics

Eritherium is the oldest known representative of the Proboscidea, although it remains unassigned to any family within this order. [1] Fitting with its great age, Eritherium is basal to all other primitive proboscideans (including Phosphatherium , Numidotherium , Moeritherium and Daouitherium ) which together form one of the most complete evolutionary sequences of early mammalian radiations following the K/T extinction event. [1] Cladistic analyses suggest that the closest relatives of the proboscid lineage are the manatees (Sirenia) and Desmostylia. Together with Embrithopoda and the hyraxes (Hyracoidea) they form the group Paenungulata. The great age and location of Eritherium support the hypothesis that paenungulates originated in Africa and diversified rapidly in the Paleocene. [1]

Eritherium in cladogram after Tabuce et al., 2019: [3]

  Proboscidea  

 Eritherium

  Phosphatherium

  Daouitherium

  Numidotherium

  Barytherium

  Omanitherium

  Arcanotherium

  Saloumia

  Moeritherium

  Elephantiformes

  Deinotheriidae

History of discovery

The findings of Eritherium come from Sidi Chennane, quarry in Ouled Abdoun phosphate basin in Morocco. [1] These are 10 to 20 km south of Grand Daoui, where in 1996 (Phosphatherium) and 2002 (Daouitherium) two early proboscideans were described. The Eritherium fossils were found in the "lower bone bed" of the phosphate layer. Other fossils from this layer include earliest evidence of the carnivorous Hyaenodontidae, and a diverse assortment of elasmobranchs (sharks and rays). This places the findings in a geological time ranging from 61.1 to 57.8 million years ago. The genus was named by Emmanuel Gheerbrant (2009). The name Eritherium comes from the Greek words "eρυ" (eri: old) and "θηρίον" (therion: animal), while the species name azzouzorum honors the residents of the village of Ouled Azzouz, near where most of the fossils were discovered. [1]

Related Research Articles

<span class="mw-page-title-main">Proboscidea</span> Order of elephant-like mammals

Proboscidea is a taxonomic order of afrotherian mammals containing one living family (Elephantidae) and several extinct families. First described by J. Illiger in 1811, it encompasses the elephants and their close relatives. From the mid-Miocene onwards, most proboscideans were very large. The largest land mammal of all time may have been a proboscidean; Palaeoloxodon namadicus was up to 5.2 m (17.1 ft) at the shoulder and may have weighed up to 22 t, almost double the weight of some sauropods like Diplodocus carnegii. The largest extant proboscidean is the African bush elephant, with a record of size of 4 m (13.1 ft) at the shoulder and 10.4 t. In addition to their enormous size, later proboscideans are distinguished by tusks and long, muscular trunks, which were less developed or absent in early proboscideans.

<span class="mw-page-title-main">Desmostylia</span> Extinct order of mammals

The Desmostylia are an extinct order of aquatic mammals native to the North Pacific from the early Oligocene (Rupelian) to the late Miocene (Tortonian). Desmostylians are the only known extinct order of marine mammals.

<span class="mw-page-title-main">Elephantidae</span> Family of mammals

Elephantidae is a family of large, herbivorous proboscidean mammals collectively called elephants and mammoths. These are large terrestrial mammals with a snout modified into a trunk and teeth modified into tusks. Most genera and species in the family are extinct. Only two genera, Loxodonta and Elephas, are living.

<span class="mw-page-title-main">Paenungulata</span> Superorder of placental mammals including elephants, hyraxes, dungong and manatees

Paenungulata is a clade of "sub-ungulates", which groups three extant mammal orders: Proboscidea, Sirenia, and Hyracoidea (hyraxes). At least two more possible orders are known only as fossils, namely Embrithopoda and Desmostylia.

<i>Purgatorius</i> Extinct genus of mammals

Purgatorius is a genus of seven extinct eutherian species typically believed to be the earliest example of a primate or a proto-primate, a primatomorph precursor to the Plesiadapiformes, dating to as old as 66 million years ago. The first remains were reported in 1965, from what is now eastern Montana's Tullock Formation, specifically at Purgatory Hill in deposits believed to be about 63 million years old, and at Harbicht Hill in the lower Paleocene section of the Hell Creek Formation. Both locations are in McCone County, Montana.

Numidotheriidae is an extinct family of primitive proboscideans that lived from the late Paleocene to the early Oligocene periods of North Africa.

<i>Daouitherium</i> Extinct genus of mammals

Daouitherium is an extinct genus of early proboscideans that lived during the early Eocene some 55 million years ago in North Africa.

<i>Numidotherium</i> Genus of mammals

Numidotherium is an extinct genus of early proboscideans, discovered in 1984, that lived during the middle Eocene of North Africa some 46 million years ago. It was about 90-100 cm tall at the shoulder and weighed about 250-300 kg.

<i>Phosphatherium</i> Extinct genus of mammals

Phosphatherium escuillei is a basal proboscidean that lived from the Late Paleocene to the early stages of the Ypresian age until the early Thanetian some 56 million years ago in North Africa. Research has suggested that Phosphatherium existed during the Eocene period.

<span class="mw-page-title-main">Tillodontia</span> Extinct suborder of mammals

Tillodontia is an extinct suborder of eutherian mammals known from the Early Paleocene to Late Eocene of China, the Late Paleocene to Middle Eocene of North America where they display their maximum species diversity, the Middle Eocene of Pakistan, and the Early Eocene of Europe. Leaving no descendants, they are most closely related to the pantodonts, another extinct group. The tillodonts were medium- to large-sized animals that probably feed on roots and tubers in temperate to subtropical habitats.

<i>Hipposideros besaoka</i> Extinct species of bat

Hipposideros besaoka is an extinct bat from Madagascar in the genus Hipposideros. It is known from numerous jaws and teeth, which were collected in a cave at Anjohibe in 1996 and described as a new species in 2007. The site where H. besaoka was found is at most 10,000 years old; other parts of the cave have yielded H. commersoni, a living species of Hipposideros from Madagascar, and some material that is distinct from both species. H. besaoka was larger than H. commersoni, making it the largest insectivorous bat of Madagascar, and had broader molars and a more robust lower jaw. As usual in Hipposideros, the second upper premolar is small and displaced from the toothrow, and the second lower premolar is large.

Plesiopithecus is an extinct genus of early strepsirrhine primate from the late Eocene.

<i>Ocepeia</i> Extinct Afrotherian mammal

Ocepeia is an extinct genus of afrotherian mammal that lived in present-day Morocco during the middle Paleocene epoch, approximately 60 million years ago. First named and described in 2001, the type species is O. daouiensis from the Selandian stage of Morocco's Ouled Abdoun Basin. A second, larger species, O. grandis, is known from the Thanetian, a slightly younger stage in the same area. In life, the two species are estimated to have weighed about 3.5 kg (7.7 lb) and 10 kg (22 lb), respectively, and are believed to have been specialized leaf-eaters. The fossil skulls of Ocepeia are the oldest known afrotherian skulls, and the best-known of any Paleocene mammal in Africa.

<i>Coronodon</i> Extinct genus of whales

Coronodon is a genus of toothed (transitional) baleen whales from the Early Oligocene Ashley and Chandler Bridge formations of South Carolina. The genus contains three species: the type species C. havensteini, and additional species C. newtonorum and C. planifrons.

Saloumia is an extinct genus of the order Proboscidea. It is one of the oldest members of the order and lived in the middle Eocene of Senegal. It is known only from a single molar, whose pronounced bumpy chewing surface indicates it is probably closely related to Moeritherium.

Saxonella is a genus of extinct primate from the Paleocene Epoch, 66-56 Ma. The genus is present in the fossil record from around ~62-57 Ma. Saxonella has been found in fissure fillings in Walbeck, Germany as well as in the Paskapoo Formation in Alberta, Canada. Saxonella is one of five families within the superfamily Plesiadapoidae, which appears in the fossil record from the mid Paleocene to the early Eocene. Analyses of molars by paleontologists suggest that Saxonella most likely had a folivorous diet.

Dagbatitherium is an extinct genus of proboscideans. So far a single molar from the phosphate basins of Togo in West Africa has been found. The fossil dates to the Middle Eocene, around 47 million years ago. A striking feature of the tooth are the three pairs of cusps oriented transversely to the longitudinal axis of the tooth. This feature is found in more derived proboscideans, which are grouped in the Elephantiformes. For its age, Dagbatitherium is the earliest member of Elephantiformes to date. Furthermore, it is characterized by a low tooth crown and a humped occlusal pattern. The genus was described in 2021.

Taowu is an extinct genus of machairodonts, a type of saber-toothed cat. It lived during the Early Pleistocene about 2.5 million years ago in East Asia. So far, only one skull is known, found in northern China. Based on this, a relatively small representative of the saber-toothed cats can be reconstructed, which only reached the size of a present-day leopard. In its dentition characteristics, it mediates between phylogenetic older forms such as Amphimachairodus and younger members such as Homotherium. The genus was scientifically described in 2022, but the find material was recovered as early as the 1930s.

<i>Periptychus</i> Extinct genus of mammals

Periptychus is an extinct genus of mammal belonging to the family Periptychidae. It lived from the Early to Late Paleocene and its fossil remains have been found in North America.

Hadrogeneios is an extinct genus of afrotherian mammal recovered from the Khouribga Phosphates of the Ouled Abdoun Basin dating from the Selandian to the Thanetian. Only the type species H. phosphaticus is known for this genus, with the material being of dental and jaw specimens. The placement of Hadrogeneios recovered it to be the most basal stem-paenungulate, the clade that includes elephants, sea cows, and hyraxes. Despite this Hadrogeneios was a contemporary of more derived members of the group such as Abdounodus, Ocepeia, and the early proboscideans Eritherium, Phosphatherium, and Daouitherium.

References

  1. 1 2 3 4 5 6 Emmanuel Gheerbrant (2009). "Paleocene emergence of elephant relatives and the rapid radiation of African ungulates". Proceedings of the National Academy of Sciences of the United States of America. 106 (26): 10717–10721. Bibcode:2009PNAS..10610717G. doi: 10.1073/pnas.0900251106 . PMC   2705600 . PMID   19549873.
  2. Larramendi, A. (2016). "Shoulder height, body mass and shape of proboscideans" (PDF). Acta Palaeontologica Polonica. 61. doi: 10.4202/app.00136.2014 .
  3. Rodolphe Tabuce, Raphaël Sarr, Sylvain Adnet, Renaud Lebrun, Fabrice Lihoreau, Jeremy E. Martin, Bernard Sambou, Mustapha Thiam und Lionel Hautier: Filling a gap in the proboscidean fossil record: a new genus from the Lutetian of Senegal. Journal of Paleontology, 2019, doi:10.1017/jpa.2019.98