''Eritherium'' is an extinct

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

of early Proboscidea found in the

Ouled Abdoun basin The Oulad Abdoun Basin (also known as the Ouled Abdoun Basin or Khouribga Basin) is a phosphate sedimentary basin located in Morocco, near the city of Khouribga. It is the largest in Morocco, comprising 44% of Morocco's phosphate reserves, and a ...

(early

Thanetian The Thanetian is, in the ICS Geologic timescale, the latest age or uppermost stratigraphic stage of the Paleocene Epoch or Series. It spans the time between . The Thanetian is preceded by the Selandian Age and followed by the Ypresian Age ( ...

age),

Morocco Morocco (),, ) officially the Kingdom of Morocco, is the westernmost country in the Maghreb region of North Africa. It overlooks the Mediterranean Sea to the north and the Atlantic Ocean to the west, and has land borders with Algeria t ...

. 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 Elephants are the largest existing land animals. Three living species are currently recognised: the African bush elephant, the African forest elephant, and the Asian elephant. They are the only surviving members of the family Elephantidae ...

relative.

Description

The

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of sever ...

(specimen number MNHN PM69) is now in the Musée d'histoire naturelle - Guimet in

Lyon Lyon,, ; Occitan language, Occitan: ''Lion'', hist. ''Lionés'' also spelled in English as Lyons, is the List of communes in France with over 20,000 inhabitants, third-largest city and Urban area (France), second-largest metropolitan area of F ...

and includes an

upper jaw The maxilla (plural: ''maxillae'' ) in vertebrates is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. The t ...

(with approaches of the

zygomatic bone In the human skull, the zygomatic bone (from grc, ζῠγόν, zugón, yoke), also called cheekbone or malar bone, is a paired irregular bone which articulates with the maxilla, the temporal bone, the sphenoid bone and the frontal bone. It is s ...

and two maxillary branches, each of the two posterior

premolars The premolars, also called premolar teeth, or bicuspids, are transitional teeth located between the canine and molar teeth. In humans, there are two premolars per quadrant in the permanent set of teeth, making eight premolars total in the mouth ...

(P3 and 4) and three

molars The molars or molar teeth are large, flat teeth at the back of the mouth. They are more developed in mammals. They are used primarily to grind food during chewing. The name ''molar'' derives from Latin, ''molaris dens'', meaning "millstone to ...

(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. It was about 20 cm tall at the shoulder and weighed about 5–6 kg. Generally, ''Eritherium ''shared similarities in the structure of their teeth with other

Paenungulata Paenungulata (from Latin ''paene'' "almost" + ''ungulātus'' "having hoofs") is a clade of "sub-ungulates", which groups three extant mammal orders: Proboscidea (including elephants), Sirenia (sea cows, including dugongs and manatees), and H ...

such as the extinct

Embrithopoda Embrithopoda ("heavy-footed") is an order of extinct mammals known from Asia, Africa and Eastern Europe. Most of the embrithopod genera are known exclusively from jaws and teeth dated from the late Paleocene to the late Eocene; however, the orde ...

or early representatives of the

manatee Manatees (family Trichechidae, genus ''Trichechus'') are large, fully aquatic, mostly herbivorous marine mammals sometimes known as sea cows. There are three accepted living species of Trichechidae, representing three of the four living speci ...

s, 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

incisor Incisors (from Latin ''incidere'', "to cut") are the front teeth present in most mammals. They are located in the premaxilla above and on the mandible below. Humans have a total of eight (two on each side, top and bottom). Opossums have 18, wher ...

s, one canine, four premolars and three molars. The tooth row was closed and had no

diastema A diastema (plural diastemata, from Greek διάστημα, space) is a space or gap between two teeth. Many species of mammals have diastemata as a normal feature, most commonly between the incisors and molars. More colloquially, the condition ...

between the canine tooth on the front and back teeth. This primitive mammalian dentition is unique among Proboscideans. The molars were generally

bunodont The molars or molar teeth are large, flat teeth at the back of the mouth. They are more developed in mammals. They are used primarily to grind food during chewing. The name ''molar'' derives from Latin, ''molaris dens'', meaning "millstone to ...

(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 A symphysis (, pl. symphyses) is a fibrocartilaginous fusion between two bones. It is a type of cartilaginous joint, specifically a secondary cartilaginous joint. # A symphysis is an amphiarthrosis, a slightly movable joint. # A growing togethe ...

of the mandible. The reconstruction of the upper portion of the skull showed that the

eye socket In anatomy, the orbit is the cavity or socket of the skull in which the eye and its appendages are situated. "Orbit" can refer to the bony socket, or it can also be used to imply the contents. In the adult human, the volume of the orbit is , o ...

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. Fitting with its great age, ''Eritherium ''is basal to all other primitive proboscideans (including '' Phosphatherium'', ''

Numidotherium ''Numidotherium'' ("Numidia beast") 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- ...

'', ''

Moeritherium ''Moeritherium'' ("the beast from Lake Moeris") is an extinct genus of primitive proboscideans. These prehistoric mammals are related to the elephant and, more distantly, sea cows and hyraxes. They lived during the Eocene epoch. Description ''M ...

'' and ''

Daouitherium ''Daouitherium'' ("Sidi Daoui beast" from the name of the site where it was discovered) is an extinct genus of early proboscideans (a group including modern elephants and their extinct relatives) that lived during the early Eocene (Ypresian sta ...

'') which together form one of the most complete evolutionary sequences of early mammalian radiations following the K/T extinction event. Cladistic analyses suggest that the closest relatives of the proboscid lineage are the manatees (

Sirenia The Sirenia (), commonly referred to as sea-cows or sirenians, are an order of fully aquatic, herbivorous mammals that inhabit swamps, rivers, estuaries, marine wetlands, and coastal marine waters. The Sirenia currently comprise two distinct ...

) and

Desmostylia The Desmostylia (from Greek δεσμά ''desma'', "bundle", and στῦλος ''stylos'', "pillar") are an extinct order of aquatic mammals that existed from the early Oligocene (Rupelian) to the late Miocene ( Tortonian) (). Desmostylians are t ...

. Together with

and the hyraxes (

Hyracoidea Hyraxes (), also called dassies, are small, thickset, herbivorous mammals in the order Hyracoidea. Hyraxes are well-furred, rotund animals with short tails. Typically, they measure between long and weigh between . They are superficially simila ...

) they form the group

. The great age and location of ''Eritherium'' support the hypothesis that paenungulates originated in Africa and diversified rapidly in the Paleocene.

History of discovery

The findings of ''Eritherium ''come from Sidi Chennane, quarry in

Ouled Abdoun The Oulad Abdoun Basin (also known as the Ouled Abdoun Basin or Khouribga Basin) is a phosphate sedimentary basin located in Morocco, near the city of Khouribga. It is the largest in Morocco, comprising 44% of Morocco's phosphate reserves, and a ...

phosphate basin in Morocco. 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 Hyaenodontidae ("hyena teeth") is a family of extinct predatory mammals from extinct superfamily Hyaenodontoidea within extinct order Hyaenodonta. Hyaenodontids arose during the early Eocene and persisted well into the early Miocene. Fossils of ...

, and a diverse assortment of

elasmobranchs Elasmobranchii () is a subclass of Chondrichthyes or cartilaginous fish, including sharks (superorder Selachii), rays, skates, and sawfish (superorder Batoidea). Members of this subclass are characterised by having five to seven pairs of gil ...

(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.

References

{{Taxonbar, from=Q1354868 Fossil taxa described in 2009 Paleocene proboscideans Transitional fossils Prehistoric monotypic mammal genera Paleocene mammals of Africa Prehistoric placental genera