Tag Archives: Eocene

Know Your Bones: June 2014

Last month’s challenge will have a huge contrast to this month’s challenge. Before we get to that, we must name the winner. Isotelus came the closest with:


Those dainty little toes remind me of

Hyracotherium (vasacciensis…I think)


Hyracotherium vasacciensis is now considered a junior synonym for Eohippus angustidens.


(Taken at the New Mexico Museum of Natural History and Science)


When I posted this challenge, I actually did not know that the classification of H. vasacciensis had changed; I found that out doing the research for this post. It turns out that H. leporinum has more basal features shared with several perissodactyls (odd-toed ungulates) outside of the horse clade. Eohippus has features that are only present in Equidae, which is the reason behind the change.


Eohippus lived during the Eocene (56 to 33.9 million years ago) and ranged across North America. Eohippus was most likely a forest dwelling animal that fed on soft vegetation as a browser. Eohippus was ~20 cm tall and ~60 cm in length. This tiny critter had five toes on its forelegs and three on the hind legs, and would probably make an adorable pet.


Moving on to this weeks challenge:


(Taken at the New Mexico Museum of Natural History and Science)


In honor of the giant critter found in South America, I thought I would share another giant that once roamed the earth.


(Taken at the New Mexico Museum of Natural History and Science)


This second viewpoint is to help one get an idea of how large this critter once was.


Good luck.

Know Your Bones: March 2014

Last months challenge was apparently very easy. WarK was able to guess the correct answer within a matter of hours. However, later in the day Aught3 gave an even more correct answer.


Some kind of terror bird but not a moa :(


Dammit WarK!
How about Gastornis giganteus then? Just to try and be even more correct.


Aught3 is correct that this is Gastornis giganteus, formally known as Diatryma giganteus, however, Aught3 is incorrect in thinking that this is a terror bird (also, moas were not terror birds).


(Taken at the New Mexico Museum of Natural History and Science)


Gastornis ranged across much of North America, Europe, and Asia during the late Paleocene and early Eocene 56-45 million years ago. It is largely believed that Gastornis was the apex predator of its day, like the “terror birds” that inhabited mostly South America. However, Gastornis and its relatives lack the curved beak and sharp-clawed feet found in their distant cousins, the “terror birds”. The lack of those features leads some paleontologist to believe that Gastornis may have been a vegetarian, using its large beak to crack nuts and branches.


Gastornis’s skull and large size (~2 meters) often lead it to be confused with “terror birds”. Gastornis is sometimes called a “terror crane” because it is allied with the wading birds (such as cranes). Often you will see the junior synonym Diatryma used in books or museum displays. The reason this happens, I believe, is because Edward Drinker Cope, a very famous U.S. paleontologist, gave it that name after discovering a large specimen near Cuba New Mexico. This critter is also the first dinosaur to appear in the “Know Your Bones” series.


Moving on to the new challenge:



(Taken at the New Mexico Museum of Natural History and Science)


Thought I would give a challenging one this month. Good luck to everyone.