Aegyptopithecus

Aegyptopithecus Temporal range: 35–33 Ma PreЄ Є O S D C P T J K Pg N ↓ Late Eocene-Early Oligocene
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	Primates
Suborder:	Haplorrhini
Superfamily:	†Propliopithecoidea
Family:	†Propliopithecidae
Genus:	†Aegyptopithecus
Species:	†A. zeuxis
Binomial name
Aegyptopithecus zeuxis

Aegyptopithecus zeuxis means “linking Egyptian ape”. It was discovered by E. Simons in 1965.^[1][2] There is controversy over whether or not Aegyptopithecus should be a genus on its own or whether it should be moved into the genus Propliopithecus.^[2] If Aegyptopithecus is placed in its own genus, then there is one documented species named A. zeuxis.^[2] The type specimen for the species is CGM26901.^[1] Aegyptopithecus zeuxis is an early catarrhine from the early Oligocene of Jebel Qatrani Formation in the Fayum Province of Egypt. It is believed to be a basal catarrhine that precedes the divergence of Old World monkeys and apes.^[3] Aegyptopithecus zeuxis has become one of the best known extinct primates based on craniodental and postcranial remains.^[3]

Brain Size

In Egypt’s Fayum Depression, CGM 85785 was discovered by Rajeev Patnaik.^[4] CGM 85785 is a subadult female cranium of Aegyptopithecus zeuxis. This specimen’s cranial capacity was found to be 14.63 cm³ and reanalysis of a male endocast (CGM 40237) estimates a cranial capacity of 21.8 cm³.^[4] These estimates dispel earlier ones of approximately 30 cm³.^[4] These measurements, give an estimated male to female endocranial ratio of approximately 1.5, indicating A. zeuxis to be a dimorphic species.^[4]

The olfactory bulb to endocranial volume ratio is considered to be on the lower end of the strepsirrhine spectrum, perhaps as a result of the organism’s rostrum.^[4]

In relation to other anthropoids, the frontal lobes of A. zeuxis are considered to be rather small but the olfactory bulbs are not considered to be small when taking into account the body size of A. zeuxis.^[4]

Overall, the brain to body weight ratio of A. zeuxis is considered to be strepsirrhine-like and perhaps even non-primate like.^[4]

Body Size and Dimensions

Based on dental dimensions and femoral remains the body mass of A. zeuxis is estimated to be 6.708 kg.^[3]

The functional length of the femur is estimated to be 150 mm, which is larger than Cebus apella and smaller than Alouatta seniculus.^[3]

Locomotion

Three femoral remains were found in Quarry I (DPC 5262 and 8709) and Quarry M (DPC 2480). Paleomagnetic dating puts the sites at 33 Ma, consistent with the Oligocene epoch.^[3]

Based on estimated femoral neck angle (120-130 degrees) of aforementioned remains, the femur is similar to that of a quadrupedal anthropoid. The greater trochanter’s morphology is inconsistent with that of leaping primates, serving as further evidence of the animal’s quadrupedalism.^[3]

Aegyptopithecus is thought to have been an arboreal quadruped due to the distal articular region of the femur, which is deeper than that of “later” catarrhines.^[3] Also, based on overall femoral morphology, A. zeuxis is thought to have been robust.^[3]

The phalanges of the hands and feet suggest powerful grasping consistent with arboreal quadrupedalism.^[3]

In conjunction with the femur, the humerus suggests arboreal quadrupedalism. This is based on the pronounced brachialis flange and stabilizing muscles on brachial flexors rather than extensors.^[5]

In addition, the ulna and distal articular surface of the humerus indicate that A. zeuxis was not only an arboreal quadruped, but also large and slow.^[5] This is consistent with evidence extrapolated from femoral morphology.

Diet

Studies in dental microwear and microsutures focusing on the molars, suggest that Aegyptopithecus was probably a frugivore.^[6] It is also possible that Aegyptopithecus ate hard objects on occasion.^[6]

Habitat

Aegyptopithecus lived in the Fayum area of northern Egypt.^[7] Today, this area is semiarid and lacking in vegetation.^[7] At the time of Aegyptopithecus’ existence, the Oligocene, this area was heavily vegetated, subtropical, had many trees and had seasonal rainfall.^[7]

Social Structure and Sexual Dimorphism

A. zeuxis is thought to have been sexually dimorphic.^[4] Tooth size, craniofacial morphology, brain size, and body mass all indicate this. Due to A. zeuxis being sexually dimorphic, the social structure is thought to have been polygynous with intense competition for females.^[4]

References

1. ^ ^{a b} Ciochon, Russell L., and Gregg F. Gunnell (2002). "Eocene primates from Myanmar: Historical perspectives on the origin of Anthropoidea". Evolutionary Anthropology 11 (4): 156–168. doi:10.1002/evan.10032. 
2. ^ ^{a b c} Simons, Elwyn L., and D. Tab Rasmussen (1991). "The Generic Classification of Fayum Anthropoidea". International Journal of Primatology 12 (2): 163–178. doi:10.1007/BF02547579. 
3. ^ ^{a b c d e f g h i} Ankel-Simons, Friderun, John G. Fleagle, and Prithijit S. Chatrath (1998). "Femoral Anatomy of Aegyptopithecus zeuxis, An Early Oligocene Anthropoid". American Journal of Physical Anthropology 106 (4): 413–424. doi:10.1002/(SICI)1096-8644(199808)106:4<413::AID-AJPA1>3.0.CO;2-K. PMID 9712474. 
4. ^ ^{a b c d e f g h i} Simons, Elwyn L., et al (2007). "A remarkable female cranium of the early Oligocene anthropoid Aegyptopithecus zeuxis (Catarrhini, Propliopithecidae)". PNAS 104 (21): 8731–8736. doi:10.1073/pnas.0703129104. PMC 1885571. PMID 17517628. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1885571. 
5. ^ ^{a b} Fleagle, John G., and Elwyn L. Simons (1982). "The Humerus of Aegyptopithecus zeuxis: A Primitive Anthropoid". American Journal of Physical Anthropology 59 (2): 175–193. doi:10.1002/ajpa.1330590207. PMID 6816072. 
6. ^ ^{a b} Teaford, Mark F., Mary C. Maas, and Elwyn L. Simons (1996). "Dental Microwear and Microstructure in Early Oligocene Primates From the Fayum, Egypt: Implications for Diet". American Journal of Physical Anthropology 101 (4): 527–543. doi:10.1002/(SICI)1096-8644(199612)101:4<527::AID-AJPA7>3.0.CO;2-S. PMID 9016366. 
7. ^ ^{a b c} Bown, Thomas M., et al (1982). "The Fayum Primate Forest Revisited". Journal of Human Evolution 11 (7): 603–632. doi:10.1016/S0047-2484(82)80008-0. 

External links

• Aegyptopithecus, Archaeology.info site
• Aegyptopithecus zeuxis Skull, skullsunlimited.com site
• Fleagle JG, Simons EL (October 1982). "The humerus of Aegyptopithecus zeuxis: a primitive anthropoid". Am. J. Phys. Anthropol. 59 (2): 175–93. doi:10.1002/ajpa.1330590207. PMID 6816072. 
• Aegyptopithecus zeuxis, paragraph and picture on Duke University site.
• Aegyptopithecus zeuxis, article on members.tripod.com
• Rossie JB, Simons EL, Gauld SC, Rasmussen DT (June 2002). "Paranasal sinus anatomy of Aegyptopithecus: Implications for hominoid origins". Proc. Natl. Acad. Sci. U.S.A. 99 (12): 8454–6. doi:10.1073/pnas.092258699. PMC 123088. PMID 12060786. http://www.pnas.org/cgi/pmidlookup?view=long&pmid=12060786.