Tuesday, September 15, 2009

Algeripithecus and Azibius: Anthropoids or Strepsirhines?

The mandible of Algeripithecus. Photo from Science Daily.

The debate for the origin of anthropoid points to two locations. One hypothesis supports the notion that anthropoids originated from Africa while the other argues that anthropoids originated from Asia. The model for the African origin hypothesis rests on Algeripithecus minutus, a fossil discovered in Algeria, Africa that lived 45 million years old. Algeripithecus and Azibius are Eocene primates that lived around the same time in Africa some 50 million years ago.

Much more complete craniodental fossils of Algeripithecus and Azibius were recently excavated and reveal that they might not be anthropoids but were strepsirhines instead. New data from the fossils, according to a recently published paper by Tabuce et al. (2009), suggest that Algeripithecus and Azibius were the earliest primates to branch out of the Afro-Arabian strepsirhines clade.

According to Tabuce et al. (2009), there are anatomical evidence suggesting that Azibius were nocturnal. They also found that Algeripithecus has a long, thin and forwardly inclined lower canine alveolus, features that match the long and and flat lower canine in the tooth comb (dental comb) of crown strepsirhines. These physical characteristics suggest that both Algeripithecus and Azibius are closely related to crown strepsirhines. The researchers concluded that both Algeripithecus and Azibius were not members of the anthropoid family but instead an early representative of the crown strepsirhines. Crown strepsirhines gave rise to modern day lemurs, galagos and lorises.

Tooth comb of a ring-tailed lemur (Lemur catta). Notice the two lower canines that are long, thin and forwardly inclined. Together with four lower incisors, it makes up the tooth comb. Photo from Wikipedia.

These recently excavated fossils support the origin of crown strepsirhines from Africa. However, it also challenges the hypothesis that points to Africa as the origin of anthropoids since Algeripithecus should be classified as strepsirhines instead of anthropoids (and no longer provide evidence for the Africa origin hypothesis) according to this published paper by Tabuce et al.


CNRS (Délégation Paris Michel-Ange) (2009, September 15). African Origin Of Anthropoid Primates Called Into Question With New Fossil Discovery. ScienceDaily. Retrieved September 15, 2009, from http://www.sciencedaily.com­ /releases/2009/09/090915101355.htm

Rodolphe Tabuce, Laurent Marivaux, Renaud Lebrun, Mohammed Adaci, Mustapha Bensalah, Pierre-Henri Fabre, Emmanuel Fara, Helder Gomes Rodrigues, Lionel Hautier, Jean-Jacques Jaeger, Vincent Lazzari, Fateh Mebrouk, Stéphane Peigné, Jean Sudre, Paul Tafforeau, Xavier Valentin, and Mahammed Mahboubi. Anthropoid versus strepsirhine status of the African Eocene primates Algeripithecus and Azibius: craniodental evidence. Proc R Soc B 2009 : rspb.2009.1339v1-rspb20091339.

No comments: