Phosphatherium

Map showing where fossils have been found

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[4] 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).[5] 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.

The specific name honors the discoverer French paleontologist François Escuillé.

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.[6] 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.[6][7]

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.[8]

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.[9] 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.[10]

The unique traits of Phosphatherium teeth suggest them to be intraspecific. Some features of P. escuilliei 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.[11]

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.[12]

Considering its highly adapted folivorous jaw and tooth structure, Phosphatherium provides evidence of the high age of African endemism. 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.[13]

• Gheerbrant, Emmanuel; Sudre, Jean; Cappetta, Henri; Bignot, Gérard (January 1998). "Phosphatherium escuillieidu Thanétien du Bassin des Ouled Abdoun (Maroc), plus ancien proboscidien (Mammalia) d'Afrique". Geobios. 31 (2): 247–269. doi:10.1016/S0016-6995(98)80041-7.

http://mygeologypage.ucdavis.edu/cowen/historyoflife/Phosphatherium.html