Phosphatherium

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Phosphatherium
Temporal range: Late Paleocene to Ypresian
Fossil
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Proboscidea
Family: †Numidotheriidae
Genus: †Phosphatherium
Gheerbrant, Sudre & Cappetta, 1996[1]
Species:
†P. escuillei
Binomial name
†Phosphatherium escuillei
Gheerbrant, Sudre & Cappetta, 1996[1]

Phosphatherium escuillei is a basal

proboscidean that lived from the Late Paleocene (early Thanetian some 59 Ma) to the early stages of the Ypresian age.[2] Research has suggested that Phosphatherium existed during the Eocene period.[3]

Description

Restoration

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.[4] The sagittal crest, 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.[4][5]

Skull Phosphatherium, discovered in 1996

One of the main factors of Phosphatherium's 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's face by a varying degrees of muscle attachments on its upper jaw.[6]

Phosphatherium lacked a trunk. The tooth rows extend back to roughly 45% of its total skull length. The dental structures suggests that P. escuillei is a heterodont, meaning it possessed more than one type of tooth morphology.[7] 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.[8]

The unique traits of Phosphatherium teeth suggest them to be

intraspecific. Some features of P. escuilliei's teeth and jaw structures also show noticeable variation, which is related to sexual dimorphism. This suggests physiological differences existed between males and females, which ultimately suggest behavioral differences.[9]

The lower jaw reached a length of 10 cm and had a rather low body. The number of teeth was somewhat reduced compared to older proboscideans. Adult animals had the following dental formula:

Dentition
3.1.4.3
2.1.3.3

The tooth row extended over a length of 8 cm, taking up less than half of the skull length. In the upper jaw, the second

brachyodont.[1][9]

Discovery

Map showing where fossils have been found

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 (

Muséum National d'Histoire Naturelle 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.[1]

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.[9][10] Other very early proboscideans are known from the same area, the related Eritherium and Daouitherium.[11]

Taxonomy

Phosphatherium is known primarily from two maxilla fragments dated to the latest Paleocene deposits of the Ouled Abdoun Basin, Morocco, which date from the Thanetian epoch. It is one of the oldest[12] and smallest members of the Proboscidea, with an estimated shoulder height of about 30 centimetres (12 in) and body mass of 17 kilograms (37 lb).[13] Like its later relative, Moeritherium, the animal was probably an amphibious browser that fed on aquatic plants, akin to a very small tapir. Both animals are included in the family Numidotheriidae, together with Numidotherium.

Below is a phylogenetic tree based on Tabuce et al. 2019.[14]

 Proboscidea 

 Eritherium

 Phosphatherium

 Daouitherium

 Numidotherium

 Arcanotherium

 Saloumia

 Moeritherium

 Derived Proboscidea (Elephantiformes)

 Deinotheriidae

Palaeobiology

Jaw fragments

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.[15]

Considering its highly adapted folivorous jaw and tooth structure, Phosphatherium provides evidence of the high age of African

placental mammals.[10]

References

  1. ^
    S2CID 4362199
    .
  2. ^ http://www3.planetarioroma.it/content/download/4908/62991/file/637_638.pdf. Archived 2016-03-05 at the Wayback Machine
  3. PMID 17999766
    .
  4. ^
    PMID 24587000
    .
  5. doi:10.1111/j.1096-3642.2010.00637.x
    .
  6. ^ Gheerbrant, Emmanuel; Sudre, Jean; Tassy, Pascal; Amaghzaz, Mbarek; Bouya, Baâdy; Iarochène, Mohamed (2005). "Nouvelles données sur Phosphatherium escuilliei (Mammalia, Proboscidea) de l'Eocene inférieur du Maroc, apports à la phylogeny of the Proboscidea et the ongulés lophodontes". Geodiversitas. 27 (2): 239–333.
  7. ^ https://www.app.pan.pl/archive/published/app47/app47-493.pdf [bare URL PDF]
  8. ^ "Archived copy" (PDF). Archived from the original (PDF) on 2014-10-24. Retrieved 2014-10-23.{{cite web}}: CS1 maint: archived copy as title (link)
  9. ^ a b c Gheerbrant, E. ( 1 ), et al. "New Data On Phosphatherium Escuilliei (Mammalia, Proboscidea) From The Early Eocene Of Morocco, And Its Impact On The Phylogeny Of Proboscidea And Lophodont Ungulates." Geodiversitas 27.2 (2005): 239-333.
  10. ^
    doi:10.37570/bgsd-1998-44-12
    .
  11. ^ Gheerbrant, E.; Sudre, J.; Cappetta, H.; Iarochène, M.; Amaghzaz, M.; Bouya, B. (2002). "A new large mammal from the Ypresian of Morocco: Evidence of surprising diversity of early proboscideans" (PDF). Acta Palaeontologica Polonica. 47 (3): 493–506.
  12. doi:10.2113/174.3.279
    .
  13. doi:10.4202/app.00136.2014
    .
  14. ^ Rodolphe Tabuce, Raphaël Sarr, Sylvain Adnet, Renaud Lebrun, Fabrice Lihoreau, Jeremy E. Martin, Bernard Sambou, Mustapha Thiam and Lionel Hautier; 2019 "Filling a gap in the proboscidean fossil record: a new genus from the Lutetian of Senegal." Journal of Paleontology. doi:10.1017/jpa.2019.98
  15. S2CID 56260944
    .

Further reading

External links
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