Multiple species of seacows once coexisted: study

Mar 08, 2012
Sirenians, or seacows, are a group of marine mammals that include manatees and dugongs; Today, only one species of seacow is found in each world region. Smithsonian scientists have discovered that this was not always the case. According to the fossil record of these marine mammals, it was more common to find three or more different species of seacows living together at one time. This suggests that the environment and food sources for ancient seacows were also different than today. Credit: Carl Buell

Sirenians, or seacows, are a group of marine mammals that include manatees and dugongs; today, only one species of seacow is found in each world region. Smithsonian scientists have discovered that this was not always the case. According to the fossil record of these marine mammals, which dates back 50 million years ago, it was more common to find three, or possibly more, different species of seacows living together at one time. This suggests that the environment and food sources for ancient seacows were also different than today. The team's findings are published in the journal PLoS ONE.

Today there are only four of seacows―three species of , which are found in different coastal waters of the Atlantic Ocean, and one species of dugong, found along the coasts of the Indo-Pacific Ocean. All seacows are herbivores, and their diet is made up largely of seagrasses.

"The discovery that these multispecies seacow communities once existed revealed answers, but it also created new questions," said Nicholas Pyenson, curator of fossil marine mammals at the Smithsonian's National Museum of Natural History and co-author of the research. "Were these species competing against each other for seagrass resources, or were they avoiding competition by each species feeding in separate areas or on different grasses? Also, were seagrass beds structured differently in the past, or were they dominated by one seagrass species like we see today?"

To answer these questions, the team, lead by Smithsonian predoctoral fellow Jorge Velez-Juarbe, examined three localities from separate time periods, from the late Oligocene (about 23-28 million year ago) in Florida, the early Miocene (about 16-23 million years ago) in India and the early Pliocene (about 3-5 million years ago) in Mexico. All three areas showed conclusive fossil evidence that two or more species of seacow had once coexisted there.

By examining the size and dimensions of the skulls as well as estimating the body sizes, the team deduced that the different species of seacows had characteristics that allowed each to feed on different types of seagrass. Such separation among physical features, the team suggests, reduced any competition for food and allowed multiple species of seacows to coexist. This also suggests that, unlike today's seacow habitats that are dominated by one or two species of seagrass, many species of seagrass once coexisted.

Explore further: 550-million-year-old fossils provide new clues about fossil formation

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foofighter
Mar 08, 2012
This comment has been removed by a moderator.
LuckyBrandon
1 / 5 (1) Mar 08, 2012
More proof of the stupidity of man... ^ A flood NEVER HAPPENED. Learn basic geology and go check for yourself if you don't believe the current geologists....
Unless that was a smart a** comment, in which case, bravo...
Callippo
1 / 5 (6) Mar 08, 2012
This is just a problem, because in AWT all extreme stances become indistinguishable from the dual subject of their fight. For example, the surface ripples disperse into underwater at their very end, the relativistic Universe at extreme distances gets quantum behavior, the Hitler's methods were surprisingly similar to those of Stalin's, well - and many aspects of fight of atheists against creationism aren't distinguishable from the stupidity of creationists, because their only motivation is the flamewar itself.
barakn
1 / 5 (2) Mar 08, 2012
Let me draw an analogy for the method of foofighter, who is definitely a smartass and not a creationist: "I am offended that anyone would let children play in pools. They'll inevitably defecate or urinate in them. And to express my feelings on this matter, I'm going to preemptively shit in every pristine pool I find."
John_Randall
not rated yet Mar 08, 2012
the CREATOR dun dun dun
bewertow
5 / 5 (2) Mar 09, 2012
This is just a problem, because in AWT all extreme stances become indistinguishable from the dual subject of their fight. For example, the surface ripples disperse into underwater at their very end, the relativistic Universe at extreme distances gets quantum behavior, the Hitler's methods were surprisingly similar to those of Stalin's, well - and many aspects of fight of atheists against creationism aren't distinguishable from the stupidity of creationists, because their only motivation is http://www.nytime...ted=all.


Why do you insist on bringing up your crazy aether crap in every single discussion?
Evilbeagle
5 / 5 (1) Mar 12, 2012
More proof of the stupidity of man... ^ A flood NEVER HAPPENED. Learn basic geology and go check for yourself if you don't believe the current geologists....
Unless that was a smart a** comment, in which case, bravo...


I'm going to go ahead and believe that it's the latter because it boggles the mind to think that this person might be serious.

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