Phosphatherium on:
[Wikipedia]
[Google]
[Amazon]
(I2) was enlarged and conical in shape, but was perpendicular to the bone. In the lower jaw, on the other hand, the first incisor (I1) showed clear enlargements. However, both teeth did not yet form true tusks. The anterior dentition did not show a closed row of teeth, in the upper jaw there was an additional small diastema behind the first premolar. The premolars as a whole were quite simply built and not very molarised, i.e. they hardly resembled the molar. These had a bilophodont structure with two clearly formed transverse enamel ridges. The rearmost molar of the mandible, however, had a third enamel bar. In general, the teeth were brachyodont.
''Phosphatherium escuillei'' is a basal proboscidean that lived from the Late
One of the main factors of ''Phosphatherium'' body is its nontraditional musculoskeletal system. The shape of its head is composed of attributes of a snout, more vividly, turning into
a mouth with a rounded jawline. Similar mammals in its order retained a more snout-like nose, which was also a factor that pertained to it having a semiaquatic lifestyle. Furthermore, sexual dimorphism can be noticed on ''Phosphatherium'' face by a varying degrees of muscle attachments on its upper jaw.heterodont
In anatomy, a heterodont (from Greek, meaning 'different teeth') is an animal which possesses more than a single tooth morphology.
In vertebrates, heterodont pertains to animals where teeth are differentiated into different forms. For example, ...
, meaning it possessed more than one type of tooth morphology. This is evident because they possessed more than one type of molar upon fossil examinations. The various dental formations of heterodonts suggest that this animal, unlike later proboscideans, may have been omnivorous.
The unique traits of ''Phosphatherium'' teeth suggest them to be intraspecific. Some features of ''P. escuilliei''Paleocene
The Paleocene, ( ) or Palaeocene, is a geological epoch that lasted from about 66 to 56 million years ago (mya). It is the first epoch of the Paleogene Period in the modern Cenozoic Era. The name is a combination of the Ancient Greek ''pal ...
to the early stages of the Ypresian
In the geologic timescale the Ypresian is the oldest age or lowest stratigraphic stage of the Eocene. It spans the time between , is preceded by the Thanetian Age (part of the Paleocene) and is followed by the Eocene Lutetian Age. The Ypresian i ...
age until the 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 (part ...
some 56 million years ago in North Africa. Research has suggested that ''Phosphatherium'' existed during the 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'', " ...
period.
Description
''P. escuillei'' possessed rather flat features, centered around a low skull and a long, straight dorsal profile. The skull itself was rather disproportionate, consisting of an elongated cranial region and a rather short rostrum. Thesagittal crest
A sagittal crest is a ridge of bone running lengthwise along the midline of the top of the skull (at the sagittal suture) of many mammalian and reptilian skulls, among others. The presence of this ridge of bone indicates that there are exceptiona ...
, the ridge along the dorsomedian line of its skull, spans across nearly half of the skull itself. The nasal cavity is high and wide, suggesting a large snout in life.
One of the main factors of ''Phosphatherium'' body is its nontraditional musculoskeletal system. The shape of its head is composed of attributes of a snout, more vividly, turning into
a mouth with a rounded jawline. Similar mammals in its order retained a more snout-like nose, which was also a factor that pertained to it having a semiaquatic lifestyle. Furthermore, sexual dimorphism can be noticed on ''Phosphatherium'' face by a varying degrees of muscle attachments on its upper jaw.heterodont
In anatomy, a heterodont (from Greek, meaning 'different teeth') is an animal which possesses more than a single tooth morphology.
In vertebrates, heterodont pertains to animals where teeth are differentiated into different forms. For example, ...sexual dimorphism
Sexual dimorphism is the condition where the sexes of the same animal and/or plant species exhibit different morphological characteristics, particularly characteristics not directly involved in reproduction. The condition occurs in most an ...
. This suggests physiological differences existed between males and females, which ultimately suggest behavioral differences.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, w ...Discovery
The first finds were probably made by a fossil dealer in the early 1990s from an unknown location. The two fragments of the upper jaw were coated with phosphate, and the preparation of the finds revealed the tooth of a fossil shark, which dates to the late Paleocene (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 (part ...
) and thus confirms the ancient age of the finds. The holotype (copy number MNHN PM2) consists of a right upper part of the jaw with the last two premolars and the first two molars (P3 to M2). It is now in the Muséum National d'Histoire Naturelle
The French National Museum of Natural History, known in French as the ' (abbreviation MNHN), is the national natural history museum of France and a ' of higher education part of Sorbonne Universities. The main museum, with four galleries, is loca ...
in Paris. The first scientific description took place in 1996 by Emmanuel Gheerbrant and colleagues. The name Phosphatherium is made up of the Greek words φωςφορος (phosphoros "light-bearing") and θηρίον ( thērion "animal") and refers to the fact that it is stored in phosphate-containing sediments. The only known species is Phosphatherium ''escuilliei''. The species name ''escuilliei'' honors the person who found the type fossils, François Escuillié. The first description was largely limited to the tooth features, a more extensive template of the then known find material was only published two years later.
The first fossil finds were discovered in the north-eastern part of the Ouled Abdoun Basin in a phosphate-containing layer. However, they only comprised two fragmented upper jaws. However, the exact location of this find was not known. Further and much more extensive finds were discovered in the early 2000s in the same basin in the ''Grand Daoui'' area. This consists of numerous skull fragments, mandibles and some limb elements.Eritherium'' and '' Daouitherium''.
Taxonomy
''Phosphatherium'' is known primarily from twomaxilla
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 ...
fragments dated to the latest Paleocene deposits of the Ouled Abdoun Basin, 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 ...
, which date from the 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 (part ...
epoch. It is one of the oldest and smallest members of the Proboscidea
The Proboscidea (; , ) are 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. Fr ...
, with an estimated shoulder height of about and body mass of . Like its later relative, '' Moeritherium'', the animal was probably an amphibious browser that fed on aquatic plants, akin to a very small tapir
Tapirs ( ) are large, herbivorous mammals belonging to the family Tapiridae. They are similar in shape to a pig, with a short, prehensile nose trunk. Tapirs inhabit jungle and forest regions of South and Central America, with one species inh ...
. Both animals are included in the family Numidotheriidae, together with '' Numidotherium''.
Below is a phylogenetic tree based on Tabuce ''et al''. 2019.Palaeobiology
''Phosphatherium'' is thought to have had a broad diet. The dental microwear patterns observed on their teeth show lengthy scratches on the molars of juveniles. Correspondingly, similar patterns are found on adult individuals. Through study of the wear and specifically scratches on the teeth of ''Phosphatherium'', the food items it ingested include shrubs and bushes, indicating a mixed feeding preference. Adult molars are found to have a much higher density of scratches, indicating abrasive food sources and possibly insects and small animals. Overall, ''Phosphatherium'' is thought to be an omnivorous browser mainly determined by its preferences, as well as the availability of resources.
Considering its highly adapted folivorous jaw and tooth structure, ''Phosphatherium'' provides evidence of the high age of African endemism
Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found els ...
. The dental structure of ''Phosphatherium'' suggests its diet consisted mainly of leaves, which indicates it may have fulfilled a niche role in its environment, although diet can only be inferred. The discovery of this animal has ultimately helped reinforce the African origin of proboscideans, and provide insight into the radiation of modern orders of placental mammals.
References
* http://mygeologypage.ucdavis.edu/cowen/historyoflife/Phosphatherium.html {{Taxonbar, from=Q134951 Paleocene proboscideans Eocene proboscideans Ypresian extinctions Transitional fossils Paleocene mammals of Africa Eocene mammals of Africa Prehistoric placental genera Prehistoric monotypic mammal genera Fossil taxa described in 1996