Posts Tagged ‘river cat’

The Interglacial Invasion of Warm Climate Species into Southeastern North America

January 21, 2012

Humans have been enjoying a relatively stable warm climate phase for roughly 11,000 years now–a period of time known as the Holocene.  We’ve probably been experiencing an interglacial because it’s likely we’re between Ice Ages, although with the extraordinary release of CO2 from industrial activities, there’s no telling when the next Ice Age will occur.  This phase of warm stable climate has allowed agriculture to flourish.  If climate had remained unstable and as cool as it did during the last Ice Age, civilization as we know it may never have come into existence.

The most recent interglacial previous to the present one was the Sangamonian Interglacial which lasted from 132,000 BP-118,000 BP.  Climate during the Sangamonian was even warmer than that of today.  At one point during this interglacial the north polar ice cap completely melted and sea levels were higher than they are now.  Cypress swamps grew as far north as Illinois, alligators swam in rivers flowing through what today is Missouri, and giant tortoises roamed the ridge and valley region of the southern Appalachians.  This wasn’t the warmest era in geological history–it wasn’t even close to as warm as much of the Pliocene, Miocene, Oligocene, etc. ages–but it was unusually warm compared to most of the Pleistocene.  This prolonged warm climate phase allowed many frost sensitive species of vertebrates to colonize much of southeastern North America, at least temporarily.  But because cold phases of climate during the Pleistocene lasted 10 times longer than warm phases, fossils of these tropical and subtropical species are in some cases extremely rare.  There are probably more species than the following pictorial cavalcade illustrates, but these are the ones confirmed by science.

Eremotherium laurillardi, the largest ground sloth to ever live in North America, grew to 18 feet long and weighed up to 3 tons.  Fossils of this species are quite common along Georgia’s coastal fossil sites which mostly date to the Sangamonian and early Wisconsinian.  Cold climate eventually drove them from what is now Georgia, but they persisted in Florida until maybe 30,000 BP when the beginning of the LGM became too cold for them even there.  They did continue to live in South America until 10,000 BP when hunting Indians likely drove them to extinction.  If it wasn’t for man, they may have recolonized the gulf coast of today.  2 species of ground sloths (Jefferson’s and Harlan’s) were able to survive in North America during the Ice Age, but Eremotherium must have been incapable of tolerating frosts.

Evidence that the South American marsh deer (Blastoceras dichotomous) once lived in the southeast comes from 1 mandible found at Saber-tooth Cave in Florida.  It was given the scientific name, Blastoceras extraneous, but was likely the same species populating the present day South American pampas.  Dr. Richard Hulbert expressed doubt in his book, The Fossil Vertebrates of Florida, that this mandible was correctly identified, but that was before he himself indentified the presence of collared peccaries in the Florida Pleistocene–a big surprise.

Collared peccaries were only identified from the Florida Pleistocene within the last few years.  Apparently, they colonized the south during the Sangamonian and probably other interglacials.  2 other species of peccaries–the flat-headed and the long-nosed–did commonly occur in the south during cold stages as well.

1 ocelot specimen from the Florida Pleistocene proves this cat lived in the south.  It seems that this cat should be able to survive in Florida today.  I suspect Indians coveting its spotted coat led to its demise there.

Fossil evidence of a small species of cat resembling the modern day margay comes from Florida and 2 widely separated sites in Georgia–Ladds and the Isle of Hope site.  Scientists are uncertain of the identification–it’s either a margay,  jaguarundi, or a distinct extinct species.  Despite the scientific genus name, Leopardus, it’s not at all closely related to a leopard.  Was it climate or paleo-Indian desire for spotted coats that restricted this species to isolated jungles?

Giant tortoise fossils dating to the Pleistocene were found at Ladds, the northernmost locality, though during the Pliocene, which was mostly warmer than the Pleistocene, they lived as far north as Kansas.  In contradiction to what most scientists think, I suspect giant tortoises were capable of surviving light frosts.  See my reasoning in a blog entry from my April 2011 archives.

In the Sangamonian of Georgia I suspect alligators may have ranged into the Etowah River.  If giant tortoises lived in the area, alligators surely must have been able to live there too.

Many species of South American and Central American birds also extended their range north in Sangamonian times.

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Pleistocene Fossil Felid Ratios from the University of Florida Database

January 16, 2012

I followed the same procedure from last week’s study but counted the number of cat fossils in the University of Florida’s Natural History Museum database instead of dog fossils.  I only counted fossils dating from the Rancholabrean Land Mammal Age 300,000 BP-11,000 BP.  The results may be off a little because I was scrolling down while looking at a computer screen.  The results may also be misleading because many specimens may come from just 1 individual.   Nevertheless, I think the data reveals a good estimate of the ratio of species composition during the Pleistocene.

Listed on the University of Florida Museum of Natural History database, I counted 46 jaguar (Panthera onca) specimens, 21 giant panther (Panthera atrox) specimens, 42 saber-tooth (Smilodon fatalis) specimens, 6 scimitar-tooth (Dinobastis serum) specimens, 41 cougar (Puma concolor) specimens, 46 bobcat (Lynx rufus) specimens, 12 river cat (Leopardus amnicola or weidii) specimens and 1 ocelot (Leopardus pardalis) specimen.

The results are similar to those reported by the amateur fossil collectors who post on the fossil forum.  The most significant difference between their reports and database information is abundance of jaguar to saber-tooth abundance.  Amateur fossil collectors claim jaguar fossils are much more common in Florida than saber-tooth, though they do collect the latter and some have found scimitar-tooth specimens as well which are rare in the database.  It may be that the UF database includes a skeleton of a saber-tooth accounting for multiple specimens from 1 individual.

Dire wolves accounted for 64 specimens in my previous study, making them 33% more common, at least in the fossil record than any single species of big cat.  Overall, big cats combined outnumbered dire wolves 156 to 64, making large felines more than twice as common as dire wolves.  Perhaps there was less competition among species of canids, but more among felids.

Pleistocene habitats favorable to various species of big and small cats varied widely.  Mesic oak forests and cypress swamps, which expanded during warm interglacials and interstadials, favored jaguars, river cats, and ocelots.  Jaguars are adabtable enough to live in desertlike brush conditions which were common during cold arid stadials.  Cougars and bobcats thrive in many different types of environments.  The exact environments favored by giant panthers, saber-tooths, and scimitar-tooths is unknown, but it’s likely they were capable of adapting to many different ecotones.

Saber-tooths were evidently one of the most common large carnivores south of the ice sheets in North America.  They were actually no larger than a modern day jaguar.  Saber-tooths never colonized Eurasia, but a distant cousin, the scimitar-tooth had close relatives that did live from the southern tip of Africa to Alaska.  Scimitar-tooths also had longer front legs but these were more slender than those of the saber-tooth.  Their fangs were also smaller and more curved.  In Africa, Asia, and Europe scimitar-tooths became extinct much earlier than saber-tooths did in America.  I suspect they never learned to fear man, explaining their earlier extinction.  I suggest fanged cats didn’t often back down from anything.  Scimitar-tooths probably colonized southeastern North America during stadials when grasslands expanded due to dry climate which in turn caused an increase in the populations of ungulates. 

Giant panthers probably resembled large maneless lions.  True lions did live in Alaska and across Eurasia.  But south of the ice sheets in North America, the common ancestor split into 2 different species–Panthera atrox and Panthera onca.

8 cat 10 Biggest Cats in the History

This image comparing Pleistocene jaguars with modern jaguars may be a slight exaggeration, but jaguars did grow bigger during the Pleistocene because they preyed on larger mammals and had more competition among carnivores.

I’ll write more about the presence of margays and ocelots in Pleistocene Florida in my next blog entry.

Here are some related articles about big cats from my archives.

“Panthera atrox! What Kind of Cat was it?”– https://markgelbart.wordpress.com/2010/07/28/panthera-atrox-what-kind-of-cat-was-it/

“Why did fanged cathttps://markgelbart.wordpress.com/tag/saber-tooth/s have sloping backs and large forelimbs?”–

“Two new studies of saber-tooths.”– https://markgelbart.wordpress.com/2011/07/08/two-new-studies-of-sabertooth-smilodon-fatalis-anatomy/

“Cougars vs. jaguars”–https://markgelbart.wordpress.com/2010/07/08/cougars-vs-jaguars/