Navigation Links
Fossil evidence of missing link in the origin of seals, sea lions, walruses found in Canadian Arctic
Date:4/22/2009

Pittsburgh, PennsylvaniaResearchers from the United States and Canada have found a fossil skeleton of a newly discovered carnivorous animal, Puijila darwini. New research suggests Puijila is a "missing link" in the evolution of the group that today includes seals, sea lions, and the walrus. The analysis of the skeleton and support for the hypotheses that pinniped origins can be found in the Arctic will be described in the April 23 issue of the journal Nature.

Modern seals, sea lions, and walruses all have flipperslimb adaptations for swimming in water. These adaptations evolved over time, as some terrestrial animals moved to a semi-aquatic lifestyle. Until now, the morphological evidence for this transition from land to water was weak.

"The remarkably preserved skeleton of Puijila had heavy limbs, indicative of well developed muscles, and flattened phalanges which suggests that the feet were webbed, but not flippers. This animal was likely adept at both swimming and walking on land. For swimming it paddled with both front and hind limbs. Puijila is the evolutionary evidence we have been lacking for so long," says Mary Dawson, curator emeritus of Carnegie Museum of Natural History.

Portions of the Puijila darwini specimen were found in 2007 in deposits that accumulated in what was a crater lake in coastal Devon Island, Nunavut, Canada. A subsequent visit in 2008 yielded the basicranium, an important structure for determining taxonomic relationships.

Paleobotanic fossils indicate this location during the Miocene had a cool, coastal temperate environment, similar to present-day New Jersey. Given that freshwater lakes would freeze in the winter, it is likely that Puijila would travel over land to the sea for food. The transition from freshwater to saltwater in semi-aquatic mammals has been hypothesized for some time, first by Charles Darwin, who wrote in On the Origin of Species by the Means of Natural Selection, "A strictly terrestrial animal, by occasionally hunting for food in shallow water, then in streams or lakes, might at last be converted in an animal so thoroughly aquatic as to brace the open ocean."

"The find suggests that pinnipeds went through a freshwater phase in their evolution. It also provides us with a glimpse of what pinnipeds looked like before they had flippers," says Natalia Rybczynski, leader of the field expedition.

The animal is described as having a long tail, and fore-limbs comparatively proportionate to modern carnivorous land animals as opposed to pinnipeds. It is the first mammalian carnivore found at the site. Other fossils found include two taxa of freshwater fishes, one bird, and four mammalian taxa: shrew, rabbit, rhinoceros, and small artiodactyl (small short-legged herbivores, ancestors to modern giraffes and deer).

The earliest well-represented pinniped, Enaliarctosa marine form with flippershas been found on northern Pacific shores of North America. It had been theorized for some time that pinniped evolution had been centered around the Arctic; the discovery of Puijila adds credence to this theory.


'/>"/>

Contact: Laura Sutin
lsutin@mus-nature.ca
613-566-7493
Carnegie Museum of Natural History
Source:Eurekalert  

Related biology news :

1. Fossils suggest earlier land-water transition of tetrapod
2. Fossil fragments reveal 500-million-year-old monster predator
3. Cretaceous octopus with ink and suckers -- the worlds least likely fossils?
4. One-fifth of fossil-fuel emissions absorbed by threatened forests
5. Famous fossil Lucy scanned at the University of Texas at Austin
6. Origin of claws seen in 390-million-year-old fossil
7. Worlds largest snake discovered in fossilized rainforest
8. Early whales gave birth on land, fossil find reveals
9. Dinosaur fossils fit perfectly into the evolutionary tree of life
10. Hobbit fossils represent a new species, concludes University of Minnesota anthropologist
11. Bacterial biofilms as fossil makers
Post Your Comments:
*Name:
*Comment:
*Email:
Related Image:
Fossil evidence of missing link in the origin of seals, sea lions, walruses found in Canadian Arctic
(Date:2/1/2016)... Feb. 1, 2016  Today, the first day of ... plans to develop a first of its kind workplace ... IBM Watson. In the first application of ... IBM ), and Welltok will create a new ... with cognitive analytics, delivered on Welltok,s health optimization platform. ...
(Date:1/25/2016)... Jan. 25, 2016  Glencoe Software, the world-leading supplier ... publication industries, will provide the data management solution OMERO ... Photo ... Phenotypic analysis measures the characteristics ... allowing comparisons between states such as health and disease, ...
(Date:1/20/2016)... 2016   MedNet Solutions , an innovative SaaS-based ... clinical research, is pleased to announce the attainment of ... the result of the company,s laser focus on (and ... , it,s comprehensive, easy-to-use and highly affordable cloud-based technology ... Key MedNet growth achievements in 2015 include: ...
Breaking Biology News(10 mins):
(Date:2/10/2016)... 2016  The Maryland House of Delegates and House ... University of Maryland School of Medicine Dean E. ... Maryland Medical System President and CEO Robert Chrencik ... highest honor given to the public by the leader ... Reece and Mr. Chrencik for their contributions to ...
(Date:2/10/2016)... , ... February 10, 2016 ... ... today announced that it has joined the Human Vaccines Project, a public-private ... diseases and cancer. , The Human Vaccines Project brings together leading ...
(Date:2/10/2016)... , Feb. 10, 2016  Matchbook, Inc., ... for fast growing biotech companies, announced today the ... Procurement Strategic Advisor. Jim brings nearly 25 years ... and procurement, having spent nearly two decades in ... Chain/Logistics and Procurement at Genzyme and, most recently ...
(Date:2/10/2016)... NY (PRWEB) , ... February 10, 2016 , ... LATHAM, ... packages at the SPIE Photonics West conference in San Francisco’s Moscone Center ... 14 in the same venue. , These latest InGaAs PIN diode standard packages ...
Breaking Biology Technology: