|Lowland gorilla (Gorilla gorilla) female and young |
at the Bronx Zoo - Wikipedia Commons (CC-BY-SA 3.0)
|Placenta of Gorilla gorilla showing invasion of decidua (at left) by|
trophoblasts (black stain) following the interstitial route;
villi and intervillous space are at right
|Fetus of Gorilla gorilla photographed by Louis Bolk|
Courtesy of Dr. Laurens de Rooy, Museum Vrolik, Amsterdam
We have not been able to find a gravid uterus of an orangutan. The split between orangutan and other great apes was as deep as 15-19 Mya (here). It would be interesting to know whether human-like trophoblast invasion evolved before or after that.