Ratha's Creatures - What is the Blubber-tusker?

Jan 24, 2008 13:05

Before our little heroine in Ratha and Thistle-chaser meets Splayfoot the seamare, Newt/Thistle encounters another sea-beast that puzzles her. This one actually helps Newt, although she doesn't realize it at first, and probably wouldn't admit it later. By stealing this animal's leavings of clams and other shellfish, Newt learns to eat seafood. So, what is this creature who unintentionally aids her survival?
Here's some description from the book:

“It looked immense, whiskered and blubbery. Creases formed in the rolls of fat around its neck as it swung its head from side to side. Its muzzle was wide and pushed in. Short but massive tusks protruded from beneath a loose, slobbery upper lip.”

In Newt's mind, the creature becomes the “blubber-tusker”. Here's a bit more from pp. 10-12 of Ratha and Thistle-chaser:

“With a startled grunt, the blubber-tusker heaved itself upright and stared at her with eyes spaced so far apart they seemed about to fall off the sides of its pug-nosed face.”

“She had almost reached the shell-bed when the creature bellowed and wriggled toward her, its heaving motion sending ripples through its blubber.”

An elephant seal? That description could fit the huge California pinniped. However, recall from the previous installment that most seals and sea-lions were still pretty small. Enaliarctos, the “barking raider” and a very early sea-lion, was still in the otter-like stage. However, one branch of the family had rapidly achieved heavyweight status, namely the walruses.

Paleontologists now think that sea-lions and walruses descended from a canid (dog/wolf) ancestor and seals from a mustelid (weasel/otter) ancestor. Sea-lions and walruses evolved in the Pacific Ocean while seals originated in the Atlantic and migrated to the Pacific. Walruses made the trip the other way, from Pacific to Atlantic. Then they became extinct in their original home and a branch migrated back to the Pacific to fill the walrus vacancy there.

Is Thistle-chaser's blubber-tusker the long-tusked whiskered gentleman we know from Lewis Carrol's poem “The Walrus and the Carpenter”, namely a modern species? No. Thistle's animal is a very early walrus which still has some of the characteristics of its sea-lion ancestry. It's canine teeth have developed into tusks for raking shellfish, but they have not attained the length of the modern species. Certain aspects of its skull are very sea-lion-like. Paleontologists who study this creature's fossilized bones have named it Aivukis, and it really was grunting and and wriggling around on the beaches of the California Miocene.

I made one semi-deliberate goof when I portrayed Aivukis as being contemporary with the early sea-lion, Enaliarctos. In truth, Aivukis appeared later. Walruses (family Odobenidae) developed from the early sea-lions (family Enaliarctidae). The first walrus was an animal that was larger than the early sea-lions, but still had sea-lion teeth, a creature called Neotherium. I used Aivukis since it looked and behaved differently from Enaliarctos. One might call this a bit of poetic license, although the fossil record isn't exactly a time machine. No one knows exactly happened back then, which makes it a fun playground for a series.

Below is artist's Michael Long's interpretation of Aivukis ( from Savage and Long, Mammal Evolution: An Illustrated Guide. This book was a real source of inspiration for the beach setting of Ratha and Thistle-chaser. It deserves to come back into print.)




Whether or not it was involuntarily sharing its dinner with a limping little feline can't be told from fossils, but it could have happened!
This artist's re-creation of the creature helped inspire my description (“eyes so wide apart, etc.”)

Next up - Ratha's Challenge and the face-tails.

ratha, thistle-chaser, aivukis, miocene, the named, enaliarctos, thakur, california, sea-lions, clare bell, walruses, seals

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