Station 3: Eocene Primates: Adapids and Omomyids

The Eocene epoch lasts from about 56 to 34 mya, and began with very warm global temperatures.  Forests and wetlands covered the planet with tropical plants appearing even at the poles (Palm trees in Alaska and Greenland!!).  Halfway through the Eocene the climate changed dramatically with many places experiencing seasonal variations in climate. Deciduous trees proliferated. By the end of the Eocene, global climate was very cold at the poles, and it was then that the Antarctic polar cap was formed.  Many new species of mammals appeared in the Eocene including hoofed animals.  Eocene animals of all sorts were very small –  even the largest weighed no more than 20 lb. 

During the Eocene is when we see the emergence of the first true primates, also known as euprimates. Examples of euprimates from the Eocene include Adapids and Omomyids. Adapids are members of the family Adapidae.  They are considered to be ancestors to the strepsirrhines.  Members of the family Omomyidae (the Omomyids) are considered to be quite similar to the Tarsier, and therefore likely ancestors to the haplorrhines.   

Adapis Skull

4. Crania of Leptadapis (A) and two Magnadapis species (B, C) in dorsal views (A-C) at the same scale (bar is 4 cm), and ventral views of their palates (D-F) at another scale (bar is 3 cm). QU 11002 is the type specimen of L. magnus (A, D); QU 10875 is the type specimen of M. quercyi n. gen. n. sp. (B, E), and QU 10870 is the type specimen of M. intermedius n. gen. n. sp. (C, F). Note differences in interorbital breadth, medial orbital rims and muzzle breadth between the two genera in A-C, and differences in palate breadth and anterior outline in D-F. 
Image of 2 species of Adapidae– Leptadapis (A/D) and Magnadapis (B/E and C/F). Image credit: Sebastien Couette.

Adapis by Kelly Goldberg on Sketchfab

Adapiform | fossil primate | Britannica
Artistic interpretive rendering of what Adapids may have looked like. This drawing based off fossil finds of genus Northarctus. Image Credit: Encyclopaedia Britannica 2012.

Fun Fact: George Cuvier (of Catastrophism fame) named this genus.  The remains he was working with were very distorted, and he thought that they were some kind of elephant.  Adapis was a non-scientific name for the Hyrax – a furry, rotund, animal that look like a guinea pig but is actually more closely related to elephants and manatees.  They are found in Africa and SW Asia.

Omomyids

Anaptomorphus-descent-primates.jpg
Omomyidae - Wikipedia
faculty.cascadia.edu - /tsaneda/anth205/lectures/unit2/
ANTH 42: Primates in Nature Quiz clock 18 10 Omomyids Anthropoid origins China

Compare the fossil and living forms listed below, using the specimens and illustrations provided (Adapis top left, Omomyid top right, Ring Tailed lemur bottom left, Tarsier bottom right).

Adapis by Kelly Goldberg on Sketchfab

Anaptomorphus-descent-primates.jpg
Omomyid skull

Ring Tailed Lemur by Kelly Goldberg on Sketchfab

Tarsier by Kelly Goldberg on Sketchfab

Station 3 Reflection Questions

1. Look at the relative size of the orbits of the tarsier versus those of a monkey and a lemur (see other stations). What can we tell about the activity patterns (diurnal vs nocturnal) from fossilized remains

2. Adapids are thought to be ancestral to what modern forms?

3. Omomyids are thought to be ancestral to what modern forms?

Back to Start of Lab 7
To Station 4: Oligocene Primates
css.php