Aegyptopithecus
Encyclopedia
Aegyptopithecus zeuxis means “linking Egyptian ape”. It was discovered by E. Simons in 1965. 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
. If Aegyptopithecus is placed in its own genus, then there is one documented species named A. zeuxis. The type specimen for the species is CGM26901. 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. Aegyptopithecus zeuxis has become one of the best known extinct primate
s based on craniodental and postcranial remains.
(CGM 40237) estimates a cranial capacity of 21.8 cm3. These estimates dispel earlier ones of approximately 30 cm3. These measurements, give an estimated male to female endocranial ratio of approximately 1.5, indicating A. zeuxis to be a dimorphic
species.
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
.
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.
Overall, the brain to body weight ratio of A. zeuxis is considered to be strepsirrhine-like and perhaps even non-primate like.
remains the body mass of A. zeuxis is estimated to be 6.708 kg.
The functional length of the femur is estimated to be 150 mm, which is larger than Cebus apella and smaller than Alouatta seniculus.
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.
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. Also, based on overall femoral morphology, A. zeuxis is thought to have been robust.
The phalanges of the hands and feet suggest powerful grasping consistent with arboreal quadrupedalism.
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.
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. This is consistent with evidence extrapolated from femoral morphology.
. It is also possible that Aegyptopithecus ate hard objects on occasion.
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
on its own or whether it should be moved into the genus Propliopithecus
Propliopithecus
Propliopithecus is an extinct genus of ape.The 40 cm long creature resembled today's gibbons. Its eyes faced forwards, giving it stereoscopical vision. Propliopithecus was most likely an omnivore. It is possible that Propliopithecus is the same creature as Aegyptopithecus...
. If Aegyptopithecus is placed in its own genus, then there is one documented species named A. zeuxis. The type specimen for the species is CGM26901. Aegyptopithecus zeuxis is an early catarrhine from the early Oligocene
Oligocene
The Oligocene is a geologic epoch of the Paleogene Period and extends from about 34 million to 23 million years before the present . As with other older geologic periods, the rock beds that define the period are well identified but the exact dates of the start and end of the period are slightly...
of Jebel Qatrani Formation
Jebel Qatrani Formation
The Jebel Qatrani Formation is a palaeontological formation located in Egypt. It dates to the Eocene-Oligocene period....
in the Fayum Province of Egypt
Egypt
Egypt , officially the Arab Republic of Egypt, Arabic: , is a country mainly in North Africa, with the Sinai Peninsula forming a land bridge in Southwest Asia. Egypt is thus a transcontinental country, and a major power in Africa, the Mediterranean Basin, the Middle East and the Muslim world...
. It is believed to be a basal catarrhine that precedes the divergence of Old World monkeys and apes. Aegyptopithecus zeuxis has become one of the best known extinct primate
Primate
A primate is a mammal of the order Primates , which contains prosimians and simians. Primates arose from ancestors that lived in the trees of tropical forests; many primate characteristics represent adaptations to life in this challenging three-dimensional environment...
s based on craniodental and postcranial remains.
Brain Size
In Egypt’s Fayum Depression, CGM 85785 was discovered by Rajeev Patnaik. 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 endocastEndocast
An endocast is the internal cast of a hollow object, often specifically used for an endocasts of the cranial vault. Endocasts can be man-made for examining the properties of a hollow, inaccessible space, or occur naturally through fossilisation....
(CGM 40237) estimates a cranial capacity of 21.8 cm3. These estimates dispel earlier ones of approximately 30 cm3. These measurements, give an estimated male to female endocranial ratio of approximately 1.5, indicating A. zeuxis to be a dimorphic
Sexual dimorphism
Sexual dimorphism is a phenotypic difference between males and females of the same species. Examples of such differences include differences in morphology, ornamentation, and behavior.-Examples:-Ornamentation / coloration:...
species.
The olfactory bulb
Olfactory bulb
The olfactory bulb is a structure of the vertebrate forebrain involved in olfaction, the perception of odors.-Anatomy:In most vertebrates, the olfactory bulb is the most rostral part of the brain. In humans, however, the olfactory bulb is on the inferior side of the brain...
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
Rostrum (anatomy)
The term rostrum is used for a number of unrelated structures in different groups of animals:*In crustaceans, the rostrum is the forward extension of the carapace in front of the eyes....
.
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.
Overall, the brain to body weight ratio of A. zeuxis is considered to be strepsirrhine-like and perhaps even non-primate like.
Body Size and Dimensions
Based on dental dimensions and femoralFemur
The femur , or thigh bone, is the most proximal bone of the leg in tetrapod vertebrates capable of walking or jumping, such as most land mammals, birds, many reptiles such as lizards, and amphibians such as frogs. In vertebrates with four legs such as dogs and horses, the femur is found only in...
remains the body mass of A. zeuxis is estimated to be 6.708 kg.
The functional length of the femur is estimated to be 150 mm, which is larger than Cebus apella and smaller than Alouatta seniculus.
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.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
Greater trochanter
The greater trochanter of the femur is a large, irregular, quadrilateral eminence and a part of the skeletal system.It is directed a little lateralward and backward, and, in the adult, is about 1 cm lower than the head...
’s morphology is inconsistent with that of leaping primates, serving as further evidence of the animal’s quadrupedalism.
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. Also, based on overall femoral morphology, A. zeuxis is thought to have been robust.
The phalanges of the hands and feet suggest powerful grasping consistent with arboreal quadrupedalism.
In conjunction with the femur, the humerus
Humerus
The humerus is a long bone in the arm or forelimb that runs from the shoulder to the elbow....
suggests arboreal quadrupedalism. This is based on the pronounced brachialis flange and stabilizing muscles on brachial flexors rather than extensors.
In addition, the ulna
Ulna
The ulna is one of the two long bones in the forearm, the other being the radius. It is prismatic in form and runs parallel to the radius, which is shorter and smaller. In anatomical position The ulna is one of the two long bones in the forearm, the other being the radius. It is prismatic in form...
and distal articular surface of the humerus indicate that A. zeuxis was not only an arboreal quadruped, but also large and slow. 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 frugivoreFrugivore
A frugivore is a fruit eater. It can be any type of herbivore or omnivore where fruit is a preferred food type. Because approximately 20% of all mammalian herbivores also eat fruit, frugivory is considered to be common among mammals. Since frugivores eat a lot of fruit they are highly dependent...
. It is also possible that Aegyptopithecus ate hard objects on occasion.
Habitat
Aegyptopithecus lived in the Fayum area of northern Egypt. Today, this area is semiarid and lacking in vegetation. At the time of Aegyptopithecus’ existence, the Oligocene, this area was heavily vegetated, subtropical, had many trees and had seasonal rainfall.Social Structure and Sexual Dimorphism
A. zeuxis is thought to have been sexually dimorphic. 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.External links
- Aegyptopithecus, Archaeology.info site
- Aegyptopithecus zeuxis Skull, skullsunlimited.com site
- Aegyptopithecus zeuxis, paragraph and picture on Duke University site.
- Aegyptopithecus zeuxis, article on members.tripod.com