About This Project

Ask the Scientists

What is the context of this research?

This fossil, named Allodesmus, was discovered in an ancient sea bed in California. It is clearly a pinniped (seals, sea lions and walruses), but no one is sure which one! From examining the fossils, it looks like the general shape and structure of the skeleton resembles modern sea lions, but a closer look reveals that the skull looks more like that of a seal. I will find out which by examining modern seal and sea lion skulls and skeletons, noting distinct differences, and running those through a computer program. The program will give me a family tree showing how the different species I'm comparing are related. For accuracy, I will be including DNA for all modern species.

What is the significance of this project?

Understanding how the species today came to be, is critical to understanding the world around us. Knowing whether Allodesmus was a seal or sea lion will provide the framework for understanding how swimming evolved in both seals and sea lions. Early in their evolution, pinnipeds were land mammals, which over time adapted to a life in the sea. But they each did it differently. Seals swim by moving their hind limbs side to side, kind of like a shark, while sea lions use their forelimbs in a motion that has often been described as "flying". Knowing how Allodesmus swam, and which it's more closely related to, will help us understand the transition from a land mammal to a marine mammal.

What are the goals of the project?

1. Collect data on distinct differences (characters) between the bones of seals and sea lions.

2. Examine the Allodesmus fossil to see which landmarks it has in common with each (coding the characters).

3. Enter the coded landmarks for each species into a program that will help me build their phylogenetic (family) tree.

4. Run the program (including DNA information) and see how each species is related to each other. This will tell me whether Allodesmus was a seal or sea lion!