Posts tagged pinniped

One of these things is not like the other…

First row: Walrus (Odobenus rosmarus) skeleton
Second row: Hooded seal (Cystopkora cristata) skeleton
Third row: Dugong (Dugong dugon) skeleton, Brazilian sea lion (Otaria flavescens) skeleton.

*Skulls depicted are of species in the same genus as the skeleton.

Sirenia (manatees, dugongs, and sea cows) and Pinnipedia (the seals, walruses, and sea lions) are often seen as very similar, but they came from very different lineages.

While both came from land mammals (just like all sea mammals), the pinnipeds evolved from a bear-like ancestor, who returned to the sea around 28 MYA. They’re Caniformidae, or dog-like Carnivora.

The sirens evolved from the same ancestor as the hyraxes and elephants, and returned to the sea around 50 MYA. They’re only distantly related to Cetaceans and Pinnipeds.

Vergleicheende Osteologie. Edward D’alton, 1821.

rhamphotheca: Skull of the Leopard Seal (Hydrurga leptonyx) from The zoology of the voyage of the H.M.S. Erebus & Terror, under the command of Captain Sir James Clark Ross, during the years 1839 to 1843. By authority of the Lords Commissioners of the Admiralty (1844) illustration by Benjamin Waterhouse Hawkins

rhamphotheca:

Skull of the Leopard Seal (Hydrurga leptonyx)

from The zoology of the voyage of the H.M.S. Erebus & Terror, under the command of Captain Sir James Clark Ross, during the years 1839 to 1843. By authority of the Lords Commissioners of the Admiralty (1844)

illustration by Benjamin Waterhouse Hawkins

So, can YOU tell the difference between eared pinnipeds by muzzle alone?

1. Stellar Sea Lion - Head

2. Southern Fur Seal - Head

3. Hooker’s Sea Lion - Head

4. Stellar Sea Lion - Nose/Mouth

5. Southern Fur Seal - Nose/Mouth

6. Hooker’s Sea Lion - Nose/Mouth

Transactions of the Zoological Society of London, Vol XII. 1890.

When was the last time you really looked at a walrus face? LOOK. LOOK AT THE WALRUS FACE. Transactions of the Zoological Society of London, Vol. VII. 1872.

When was the last time you really looked at a walrus face?

LOOK. LOOK AT THE WALRUS FACE.

Transactions of the Zoological Society of London, Vol. VII. 1872.

Sea Lion Skeleton vs Seal Skeleton

The Handy Natural History. Ernest Protheroe, 1919.


“Sea Bear” refers to any fur seal, but often sea lions (which weren’t good pinnipeds to hunt for pelt, unlike the other fur seals). The Handy Natural History. Ernest Protheroe, 1910.

“Sea Bear” refers to any fur seal, but often sea lions (which weren’t good pinnipeds to hunt for pelt, unlike the other fur seals).

The Handy Natural History. Ernest Protheroe, 1910.