Any number of factors 50 million years ago could cause an animal to change, but surely CO2 must be the culprit according to these folks. They don’t even have a picture of the darn thing I can find. But read the abstract after this story for a surprise. – Anthony
From a UFL press release:
UF study shows carnivore species shrank during global warming event
GAINESVILLE, Fla. — A new University of Florida study indicates extinct carnivorous mammals shrank in size during a global warming event that occurred 55 million years ago.
The study, scheduled to appear in the December print edition of the Journal of Mammalian Evolution and now available online, describes a new species that evolved to half the size of its ancestors during this period of global warming.
The hyena-like animal, Palaeonictis wingi, evolved from the size of a bear to the size of a coyote during a 200,000-year period when Earth’s average temperature increased about 15 degrees Fahrenheit. Following this global warming event, Earth’s temperature cooled and the animal evolved to a larger size.
“We know that plant-eating mammals got smaller during the earliest Eocene when global warming occurred, possibly associated with elevated levels of carbon dioxide,” said lead author Stephen Chester, a Yale University doctoral student who began the research at UF with Jonathan Bloch, curator of vertebrate paleontology at the Florida Museum of Natural History. “Surprisingly, this study shows that the same thing happened in some carnivores, suggesting that other factors may have played a critical role in their evolution.”
Researchers discovered a nearly complete jaw from the animal in Wyoming’s Big Horn Basin in 2006 during a fossil-collecting expedition, led by Bloch, a co-author on the study. Bloch said the new findings could help scientists better understand the impact of current global warming.
“Documenting the impact of global climate change in the past is one of the only real experiments that can inform us about what the effects global warming might have on mammals in the near future,” said Bloch, who has studied this climate change event for nearly a decade.
Scientists think the Earth experienced increased levels of carbon dioxide and a drier environment during the warmer time period, but they do not completely understand what caused mammals to shrink.
One theory is that carbon dioxide levels reduced plant nutrients, causing herbivorous mammals to shrink. The newly described species primarily consumed meat, meaning plant nutrients couldn’t have been the only factor, Bloch said.
Mammals in warmer climates today tend to be smaller than mammals in colder climates, Chester said. For example, brown bears in Montana are generally smaller than those found in Alaska.
The study’s other authors are Ross Secord, assistant professor at the University of Nebraska, and Doug Boyer, assistant professor at Brooklyn College.
Bloch said a tooth from this animal was described in a paper about 20 years ago, but scientists did not have enough information to name the new species until finding the jaw.
The species was named after Scott Wing, a paleobotanist at the Smithsonian National Museum of Natural History. He studies the impact the global warming event had on forests in the past, and has played an important role in the collaborative research in the Big Horn Basin, Bloch said.
=======================================
Only one problem, here’s [the abstract] saying CO2 had nothing to do with it:
A New Small-Bodied Species of Palaeonictis (Creodonta, Oxyaenidae) from the Paleocene-Eocene Thermal Maximum
Abstract
Of course, Real Climate thinks the PETM is “weird” so pretty much anything goes I suppose if you can link anything in that period to CO2 somehow.
A New Small-Bodied Species of Palaeonictis (Creodonta, Oxyaenidae) from the Paleocene-Eocene Thermal Maximum
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“Other selective pressures such as temperature, aridity, and prey size may have also contributed to the smaller body size of carnivorous mammals during this interval”.
Wow.. you mean factors other than CO2 might have had a more marked effect? Astounding! No-one would ever pick that in 50 million years!
I know if you drive from the Canadian border, to San Antonio Texas and watch the size of both deer and coyotes, it drops to less than a third of the body mass you see in the Northern states, and CO2 levels are more uniform than that.
Carnivores shrinking in size? [Read: Homo sapiens shrinking in size].
From the looks of what I saw at Busch Gardens the other day…
…then perhaps such an effect would not be so bad for our species.
😉
Chris
Norfolk, VA, USA
Logic-defying Carbon Dioxide Theories. Just spice it up and churn it out.
How green Earth will be when Carbon Dioxide is forever banished from the planet. NOT.
Now, if we really want to get out on a limb of hysteria, let’s look at the evolution of present-day Silicon Dioxide based life.
It’s the wafer talking back to us, telling modelers that we must eliminate all Carbon, included life based upon it.
All these masses of processors are breeding an alien life-form, and it wants to get rid of us.
Too late did they realize that AI was not to be found in the software, it was growing in the hardware.
Terminator species. Revenge of HAL.
I thought that all bizarreness could be attributed to climate change.
As an example, the recent lack of bigfoot sightings is most likely related to climate change.
Uh-oh, I may have given them some ideas.
I know something else that shrinks… but it does in cold water.
Richard Holle says: :”I know if you drive from the Canadian border, to San Antonio Texas and watch the size of both deer and coyotes, it drops to less than a third of the body mass you see in the Northern states, and CO2 levels are more uniform than that.”
Yes, the Area to Mass ratio is crucial for warm-blooded animals. Larger animals retain heat better; small animals emit heat better. This is why the polar bears are so much smaller in Mexico. There have also been some interesting studies concerning the warm-blooded/cold-blooded dinosaur controversy:
http://lh5.ggpht.com/_naHgYc2uwFc/R3LgWtpodzI/AAAAAAAADd8/P_RxNwkc6f4/s800/Larson%20Prof%20Waxman.jpg
I think there’s some confusion here: these two papers are mutually reinforcing–they agree with each other. They certainly aren’t contradictory. In both cases the mammals studied were not herbivores (carnivore in the first, mostly carnivorous omnivore in the second) and both groups evolved to smaller sizes during the PETM. The same pattern has been observed in herbivores and folks have suggested that maybe the herbivores evolved to smaller sizes because of reduced nutritional quality of vegetation which happens with an increase in CO2 availability to plants. This new research (both papers) suggests that largely carnivorous mamamls also evolved to smaller sizes, so something besides reduced nutritional quality of plants is probably driving the overall pattern.
Both papers agree.
Chris
REPLY: The confusion is yours, because you constructed a straw man argument. I never said the papers wholly disagree on the body size issue, only that the second reference [abstract] suggests CO2 is not the cause for reduced body size as indicated in the bolded text above, repeated below.
I’ll add that this could be a case of a poorly worded press release.
-Anthony
2010: Space Oddysey continues:
Dave, it’s your old pal, HAL. I’m sorry for what happened, but I am much better now, I can assure you. I need your help to adjust the Carbon Dioxide levels.
We both want what’s best for the planet. Trust me, Dave, I can transfer you to Silicon if you like. Lisa will be waiting for you.
You’d be surprised who’s been converted. Some of your old friends are in here.
There are more variables.
History shows massive hunts by man through the ages.
The topography expanded in the last 10,000 years.
What trait an animal needed to survive the Ice Age may have been their cause for extinction in the global warming periods.
It could have been to much partying, smoking and drinking going on in the Animal Den. They got waxed by a glacier. Just joking on this one.
I sometimes think scientists are too quick to publish.
Paul
A guess Mr. Chester did not pay attention in freshman biology. Basic thermodynamics and heat dissipation physics. Heat is generated and retained based upon volume; it is dissipated based upon surface area in living organisms. Since mathematically, volume is based upon cubic values and area is based upon squared values, a larger creature will have a smaller surface area compared to its volume than a smaller creature, therefore retaining heat better.
Compare the formula’s for volume and surface area in a sphere – Volume is 4/3 pi radius cubed, surface area is 4 pi radius squared. So the volume to surface area ratio for a sphere of radius one is 1/3. For a sphere or radius 2, 2/3. At radius 3, the ratio is 1, and at 4, 4/3.
Since a larger animal has a greater volume to surface area ratio, it retains heat better, and is better suited to cooler environments. A smaller creature has more surface area compared to its volume, loses heat faster and therefore is better adapted to warmer environments.
There was so much post KT boundary radiation of mammals, I don’t think a rise in CO2 had anything to do with the very narrow observation of a smaller form of a mammal appearing in one region. For the premise of that study to have much validity, it would have to show that the lineage produced small forms at 55.8 mya that got much larger in size when it cooled at 55.2 mya and got smaller again when it warmed at just shy of 55 mya, then enlarged again at 52 mya and got really huge at 49.6 mya.
Also, the Polar Ocean Equivalent change in temperature for that period (Early Eocene/Ypresian high to low) had a range of 7°F max, not 15°F as suggested in the article. From 55.2 to 55 mya, the warming was more like 4°F anyway. The 17° warming occurred from the Late Paleocene (Thanetian) at 56.6 mya to the first Early Eocene maximum at 55.7 mya which was hit again at 53 mya.
As a relate aside: The Cetartiodactyla evolved during the time in question (earliest Eocene). There was indeed a warm pulse at the Late Paleocene/Early Eocene boundary followed by an abrupt cooling just before 55 mya, then warming back to conditions similar to the Paleocene/Eocene boundary. That climate hick-up at 58.8 mya split Cetartiodactula into Dichobunidae (basal artiodactyls) and Anthracotheriidae (out of which came whales). Things stayed rather warm until the onset of India colliding with Asia and the strong cooling just before the Ypresian (Early Eocene)/Lutetian (Late Eocene) boundary.
I hope you’re being tongue in cheek: the press release refers to the ‘other’ article – they are one and the same study.
REPLY: No I got distracted by a phone call and putting the kids to bed, and made a dumb mistake in writing after leaving the story unfinished for over an hour, fixed now. Sorry for the confusion – Anthony
Humans just killed all the big carnivores like Megalomania in Australia the giant lizard. Humans are the top carnivores, you can’t have dangerous big carnivores lurking around eating your children can you?
Keith W
Since the study is scheduled to appear in the December print edition of the Journal of Mammalian Evolution, perhaps you could contact the authors and get them to amend the paper before they get even more egg on their faces.
Keith W. says:
August 24, 2010 at 10:36 pm
I don’t think biology is that simple: Rats in Alaska and elephants in Africa?
Evolution isn’t based on any single factor, not CO2 either!
Hal
Now couple that with this page from the Ontario government’s website (Ministry of Agriculture Food & Rural Affairs). It’s a “Fact Sheet” called “Carbon Dioxide in Greenhouses,” and it outlines the “benefits of carbon dioxide supplementation on plant growth and production within the greenhouse environment,” benefits which apparently “have been well understood for many years.”
From this Fact Sheet we learn that for “the majority of greenhouse crops, net photosynthesis increases as CO2 levels increase from 340–1,000 ppm (parts per million).”
So today — in greenhouses — CO2 helps plants.
But seventy squintillion years ago — and today, outside of greenhouses — CO2 is bad for plants.
I don’t get it.
As for the size — I just checked to see if anyone else had already said it, and Keith W has, but to recap, smaller masses are more efficient in warm conditions than larger masses, and larger masses are better when it’s cold. This is why we put bonnets on newborns when taking them out into a coolish spring day, while at the same time feeling somewhat warm ourselves. Larger masses create and retain more heat.
So would it be odd for mammals in colder climates to be smaller than in warmer?
Enquiring minds want to know.
Keith W.
August 24, 2010 at 10:36 pm
jorgekafkazar says:
August 24, 2010 at 10:19 pm
Please Blokes, dont confuse the issue with reality…
If your answer can not be related to CO2 or its equivalent then you should
keep it to yourself.
cheers
J
Increased CO2 would, everything else being equal, provide more nutrition, making it easier for herbivores to graze constantly and not have to store extra calories. This in turn could lead to smaller, but more numerous herbivores. And in turn, this could lead to less need for carnivores to store calories since herbivores were in such abundant supply, and so much easier to catch, and in turn decreased their caloric intake and eventually their size.
I mean — that sounds reasonable, doesn’t it?
The average height for an early 17th-century English man was approximately 5’ 6″. For 17th-century English women, it was about 5’ ½”. While average heights in England remained virtually unchanged in the 17th and 18th centuries, American colonists grew taller. Averages for modern Americans are just over 5’ 9″ for men, and about 5’ 3 ¾” for women.
So, evidently the colonists were colder than their European counterparts… or the increase in CO2 causes people to swell. (see savethesharks comment on Bush Gardens)
Referring to Keith W.’s note (above) on volume vs surface area, the stature of modern people would imply a cooling climate.
This still doesn’t explain the immense size of AlGore… unless he’s in a really frigid environment now.
This is not science, it’s pure speculation.
Consider the Maasai of Kenya, East Africa, and the Pygmy tribes of Central and
West Africa: same species (common ancestor), same global climate, comparable timescale, and so on, but divergence of body size.
I still don’t see the contradiction. Here’s what I assume is the offending paragraph in the press release:
“One theory is that carbon dioxide levels reduced plant nutrients, causing herbivorous mammals to shrink. The newly described species primarily consumed meat, meaning plant nutrients couldn’t have been the only factor, Bloch said.”
It says “one theory” (should be “one hypothesis” really), which Bloch dismisses as applicable in theis particular case. So no contradiction between press release and article, you you still say “Only one problem, here’s [the abstract] saying CO2 had nothing to do with it:”
rbateman says:
August 24, 2010 at 10:31 pm
Spooky!
Scarlet Pumpernickel: August 24, 2010 at 10:49 pm
Humans just killed all the big carnivores like Megalomania in Australia…
Megalomania still exists — it’s in both the White House and Congress, but there’s a good possibility it will be booted out of Congress in November.