Archive for the ‘Uncategorized’ Category

Halloween Double Feature: The Lowenmensch and Brain-Eating Amoeba

October 26, 2019

I like to watch horror movie double features on Halloween.  My favorites are the movies made by Hammer Productions, a British company that produced horror movies from 1958-1976.  Turner Classic Movies often airs these every October.  For my annual Halloween blog article I am offering a scary double feature.

The Lowenmensch is a 1 foot tall figurine found in Hohlenstein-Stedelgre Cave, Germany during 1939.  Lowenmensch means Lion-Man in German, and the sculpture depicts a half-man, half lion.  The artifact is estimated to be between 35,000 years-40,000 years old.  Archeologists attempted to reproduce it, and they discovered that it took 370 hours to sculpt.  The artist could have spent 1 hour a day for about a year to make it.  Archeologists suggest this means other people were taking care of him, while he worked on this object because life during the Stone Age consisted of constant subsistence hunting and gathering.  I disagree with this notion.  People didn’t hunt and gather at night when they might be in danger from unseen predators.  Instead, I believe they likely hung around the campfire where there was more security within a crowd of other humans.  The artist probably made this sculpture at night by the light of the campfire.

The Lowenmensch.  Just imagine a beast that was half-man, half lion…a kind of werelion instead of a werewolf 

Who knows what this object symbolizes?  Lions (Panthera spelaea) were a common species that co-existed with humans in Europe 35,000 years ago,  and humans infrequently interacted with them.  The 2 species likely avoided each other most of the time.  Apparently, humans anthropomorphized animals tens of thousands of years before Disney and Warner-Robins.

The 2nd part of this double feature is scarier because it is real.  There is a species of amoeba that eats human brains.

Computer-generated representation of the amoeba Naegleria fowleri, which causes deadly brain infections.

The brain-eating amoeba (Naeglerea fowleri).

The brain-eating amoeba lives in the bottom sediment of warm freshwater lakes and ponds.  Normally, they eat bacteria.  But if a swimmer gets amoeba-filled water in their nose, the amoeba enter the olfactory nerves and penetrate the brain.  The amoeba can’t find bacteria in the brain, so they begin eating brain cells instead, and in response the human immune system fights the invasion, causing the brain to swell.  Symptoms of amoeba meningoencephalitis include headache, fever, nausea, stiff neck, disorientation, and hallucination.  The brain swelling stops the brain’s signals to the spinal cord.   The symptoms mimic bacterial and viral meningitis, often delaying the diagnosis.  The disease has a 97% mortality rate.  There is no sure known cure, but use of an experimental drug known as miltefosine saved 1 girl’s life.  Fortunately, this disease is extremely rare.  Just 146 cases have been recorded since 1962.

The crew of the U.S. Enterprise battled a giant space amoeba in 1 of my favorite episodes of the original Star Trek.

 

Paper Clowns

April 20, 2019

When I was in my mid-20s I was not an ambitious person.  I happened to be looking through the want ads 1 day and I thought I  found an ideal job.  A company would send me the material to construct paper clowns, and I would send them back, and they would pay me $5 for each clown I constructed.  I thought I could also save money by not having to drive to work everyday.  Better yet, it sounded like a job I could manage while high on pot.  I eagerly told my mother about this opportunity, but she was not enthused.  Instead, she gently insisted I get a real job with insurance benefits and paid vacations.  I did go out and get a real job and went on to meet my wife indirectly through work.  My mom was rewarded with a granddaughter, and I avoided the ignominy of being the kind of adult who lives in their parents’ basement and never really grows up.  There are many ways my mom influenced my life, but this incident always comes to mind when I think about them.

This is my mom with my father, my younger sisters, and me in 1967.

My mother, Audrey Gelbart, was born on  August 5th, 1939, in Cleveland, Ohio.  She was the product of a mixed marriage–her mother was a Yankee from New York and her father was a southerner from Georgia.  She grew up in Willoughby, Ohio with 2 brothers and a sister.  After graduating from high school she worked as a secretary in an hospital where she met my father who was a resident doctor there.  They married in 1961 and by 1966 they had 3 children.  She raised us while my father was busy working, and she always kept her house ultra clean.  She was a patient, sweet-tempered mother and grandmother, and a devoted wife.  She took good care of my father, especially during his many health crises, until his death in 2014.  My mom passed away on April 19th 2019.  We will miss her.

Georgia Before People has Run out of Gas

January 15, 2019

This is just an heads up.  The future content of my blog is about to change.  I started this blog during March 2010 to promote my self-published book of the same name.  I really enjoyed producing new blog entries, and in many ways I think the blog was better than the book itself.  Deciphering the latest scientific journal articles related to my subject into language a layman could understand became 1 of my favorite hobbies.  I’ve managed to keep the focus of my blog on the paleoecology of southeastern North America or at least on any natural history remotely related to it for 9 years, but I just can’t do that any more–there just isn’t enough new scientific literature available.  I’m too prolific and professional paleoecologists can’t keep up.  I’m still fascinated with this obscure topic.  However, I’m tired of relying on speculation, and it seems as if I’m becoming too repetitive.  I feel like I’ve beaten a dead horse until it has turned into an unrecognizable bloody pulp.  Back in November I wrote an 800 word blog entry, then realized I’d already written about the same study a few years earlier.  I just re-blogged the original essay instead of posting a different version of it.

Translating scientific studies also puts a crimp in my writing style.  Because the science isn’t always definite, I’m forced to write awkward phrases such as “the authors of the study suggest…”  too often.  I never want to write that phrase again.

I will still write essays for my blog, but they will no longer be focused on the obscure topic of paleoecology.  I’ll still write about natural history once in a while, especially if there is a new discovery of a Pleistocene-aged fossil site in Georgia or if I have a particularly interesting idea.  But no Pleistocene fossils have been discovered in Georgia since 2006.

I’ve been reading a lot of biographies lately.  I’ll probably write more about people, history, pop culture, food, and (I’m sorry) politics.  My output may or may not become more irregular.  Nothing lasts forever.

The Page-Ladson Site in Northwest Florida

November 19, 2018

I wrote a new blog article about this last night, but then realized I’d already written an article about this subject. I’m re-running this article this week because I don’t have time to write another one before the holidays. Happy Thanksgiving.

GeorgiaBeforePeople

During the late Pleistocene sea level contracted because much of earth’s atmosphere was locked in glacial ice.  The land area of what today is Florida doubled in size, and shorelines extended 50-100 miles west into the Gulf of Mexico.  The water table fell and many present day small rivers did not yet exist.  Instead, the land was pockmarked with many spring-fed ponds that attracted herds of megafauna and other wildlife.  The basal chemistry of these waters preserved bones and organic matter, and later when water tables rose, the Aucilla River began flowing and it covered these ponds with sediment.  The Aucilla River flows over 4 known Pleistocene pond sites–Page-Ladson, Latvis-Simpson, Sloth Hole, and Little River Quarry.  These sites contain deep layers of mastodon dung deposits.  Bones and artifacts are often mixed with the ancient piles of turds, and tracks are also visible where mastodons stepped on their own shit.  Scientists…

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The Ancient Rivalry Between Cats and Dogs

January 18, 2018

The PBS documentary series, Nature, recently featured a 2 part episode about cats.  During the first episode the narrator claimed cats caused the extinction of at least 40 species of dogs after the felines colonized North America.  I knew there had to be a journal article behind this claim, so I googled “cats caused extinction of 40 dog species.”  I found the paper (referenced below) and also discovered 90% of media outlets misreported the conclusions of the study.  Cats did contribute to the extinction of many dog species, but competition with other dog species and the extinct carnivores known as Barbourofelidae were also responsible for the extinctions.

Dogs originally evolved in North America, while cats originated in Asia.  About 40 million years ago a land bridge began to periodically emerge across the Bering Strait, allowing cats and dogs to colonize each other’s continent of origin.  When cats first colonized North America there were 3 subfamilies of dogs–the Hesperocyoninae, the Borophaginae (or bone-eating dogs), and the Caninae.  The Hesperocyoninae and the Borophaginae are extinct.  All living species of dogs, jackals, wolves, and foxes belong to the Caninae subfamily.

The scientists who authored the below referenced paper collected data about climate change, and the fossil occurrences of predators including Felidae (cats), Amphicyonidae (the extinct bear-dogs), Barbourofelidae, Nimravidae (false saber-tooths), and the Ursidae (true bears).  They used statistics to determine whether climate change or competition with other carnivores caused the extinction of some species of dogs.  They concluded the extinction of 1 subfamily of dogs, the Hesperocyoninae, was caused by competition with another subfamily of dogs, the Borophaginae.  Cooler climate may have contributed to the extinction of some Borophaginae species 15 million years ago.  Finally, competition with Barbourofelidae, cats, and the surviving subfamily of dogs (the caninae) drove the remaining species of Borophaginae into extinction.

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The Barbourofelidae are an extinct group of carnivores distantly related to cats but different enough to be classified as a separate family.

The species of dogs that did become extinct were often cat-like in build and probably occupied ecological niches preferred by cats.  So cats were just better than these cat-like canids at surviving in these niches.  But the Caninae were also better adapted to survive in the constantly evolving environment.  The cat and dog species that emerged from this age-old competition have achieved a kind of stalemate.  Representatives of both naturally occur on every continent but Antarctica and Australia.  (Dingos were brought to Australia by man.)  1 species of each–Canis familiaris and Felis catus —live in our homes and compete for our affections today.

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References:

Silvestri, D.; A. Antonelli, N. Salamin, and T. Quentas

“The Role of Clade Competition in the Diversification of North American Canids”

PNAS 112 (28) 2015

R.D. Lawrence–Wildlife Writer

November 8, 2017

I enjoy deciphering articles published in scientific journals and translating them into language a layman can understand.  I learned how to do this because of my long fascination with Pleistocene ecology.  Information about Pleistocene ecology almost entirely comes from scientific journal articles, and I found the language in these publications can be unnecessarily complex and oftentimes the writing is just bad.  I had to learn how to interpret them.  Some scientists are good writers, but others are not.  R.D. Lawrence (1921-2003) was a writer who felt the same way I do about language in scientific journals.  At 1 point in his life he was studying to be a biologist.  He wrote a thesis about stickleback fish, and his professor told him it was good, but he wanted him to rewrite it in the language used by scientific journals instead of the easy to understand language Mr. Lawrence had used.  He rejected this “babblespeak” and dropped out of school.  He later wrote 36 books about Canadian wildlife and won 7 awards.

The late R.D. Lawrence relaxing at home with his pet raccoon.

R.D. Lawrence was born in Spain to a Spanish mother and an English journalist who worked for Reuters.  At the age of 14 he was separated from his family during the Spanish Civil War, and he joined the side fighting against the fascists.  (Ironically, his brother joined the fascists.)  Though just a teenager, he led 1 military attack in the sewers against the fascists.  Eventually, he escaped to southeastern France and was later reunited with his family in England.  He fought for Great Britain during World War II.  He was at Dunkirk, rode a tank in North Africa, and was severely wounded during the D-Day invasion.  His injuries ended his military career.  He moved to Canada and worked as a journalist, while studying nature in his spare time.  He gathered enough material so that he was able to start getting his books about Canadian wildlife published.  Recently, I’ve read 3 of his books.

Mr. Lawrence and his wife bought some land in the wilderness of Ontario during 1962.  Here, they built a cabin where they spent weekends.  (He still worked as a journalist during the week.)  He bought the land before most of Ontario was logged over and converted into suburbs, so much of the wildlife was naïve and not particularly afraid of people.  He wrote about his experiences at this cabin in his book, The Place in the Forest.  The semi-tame animals frequenting his cabin yard included red squirrels, fox squirrels, flying squirrels, white-footed mice, snowshoe hares, and birds.  Bird seed and table scraps encouraged the creatures of the forest to hang around the cabin, and if the door was left open, they would enter the cabin and help themselves.  Mr. Lawrence and his wife adopted 2 orphaned raccoon kits and after they were grown and freed, they often returned and joined the feast.  Mr. Lawrence also wrote about some of the less tame inhabitants in the local wilderness–beavers, deer, wolves, black bears, and birds of prey.  He didn’t let worms and insects go unnoticed either.  My favorite chapter relates his encounter with a bald-faced hornet’s nest when he was climbing a tree to photograph a hawk’s nest on another nearby tree.

Mr. Lawrence’s wife died of a brain aneurism at a quite young age, prompting him to move to British Columbia where he decided to buy a boat and travel up the Pacific coast from Vancouver to southern Alaska by himself.  He wrote about this experience in his book, Voyage of the Stella.  When he fished for salmon to eat, he often caught weird species of fish–wolf fish, Pacific lancet fish, barrel eyes, and dogfish. He fed these to the killer whales that occasionally swam near his boat, and he even dove in the water with them while wearing his scuba gear.  The killer whales never bothered him, but he once had to fend off a blue shark.  On his journey he also encountered pods of Dall’s porpoises and a pair of whale sharks.  He refueled his boat at the Indian villages that dotted the coast.  Most of the Indians were friendly, but 1 drunk tried to hit him over the head with a ketchup bottle while he was trying to eat supper at a restaurant. The brave war veteran floored the Indian with an open palm blow to the forehead.

Mr. Lawrence demonstrated even more courage in his next book, The Ghost Walker.  He spent 8 months in a wilderness cabin located in a remote area of British Columbia that was 60 miles from the nearest town, and the only feasible connection to civilization was an hazardous canoe ride down a river.  He used this makeshift cabin as an home base for tracking a large male cougar.  He gained the cougar’s trust, and the big cat let the man follow him around.  Mr. Lawrence experienced several dangerous situations, aside from trusting the cougar not to turn around and eat him.  During a blizzard, Mr. Lawrence sought shelter in a creekside cave but found himself staring eye-to-eye with an hibernating grizzly bear.  Mr. Lawrence popped out of the cave like a “champagne cork” and fled, dropping his backpack which the angry bear tore to shreds. On another occasion he slipped down an icy slope, hit a tree, and sustained a concussion.  He administered his own first aid.  He often tracked the cougar after sunset, walking in the dark woods by himself for hours.  He was 1 brave soul.

I have 1 criticism of Mr. Lawrence.  He imagined he had established ESP connections with a cougar and a killer whale.  There is no rational scientific basis for his belief.  I’m sure it was his imagination, not an ESP connection.  He was just lucky the animals he “communed” with didn’t decide to attack and eat him.

 

No Need for Males

September 23, 2017

I probably read the novels At the Earth’s Core and Pellucidar about 20 times when I was between the ages of 10 and 15.  They were written by Edgar Rice Burroughs, creator of Tarzan, who also wrote a crossover novel entitled Tarzan at the Earth’s Core. The world Burroughs created fascinated me.  An old scientist, accompanied by a classic American hero, builds a drilling machine that takes them to the center of the earth where they find a land of dinosaurs, pre-historic mammals, friendly natives, and barbaric ape-like cavemen known as the Sagoths.  The novels are full of chivalrous nonsense.  After the hero, David Innes, saves a beautiful native woman from being ravaged by a Sagoth he makes a faux pas–according to the custom among the natives of this world, a saved woman was to be embraced and kissed and made a mate or freed.  Innes didn’t know he was supposed to place his hand over her head to symbolize her freedom, otherwise she was considered his slave.  It takes him a while to realize his mistake and right his wrong.  Later, he has to save her again from a race of intelligent dinosaurs that rule this world.  This race of all female dinosaurs, known as the Mahars, raise humans like livestock.  Whenever they want something to eat, they hypnotize, then eat their human chattel.

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Illustration of human being hypnotized by intelligent parthenogenetic dinosaur in Edgar Rice Burroughs’ At the Earth’s Core.  In this fantasy novel the intelligent all female dinosaurs enslaved and fed upon humans until they were routed by the hero from the earth’s surface.

In Burroughs’s novel the Mahars used science and technology to eliminate the need for males, but in the real world evolution has eliminated males in 80 species of reptiles, amphibians, and fish.  Organisms that produce viable eggs without mating are known as parthenogenetic.  Species that are all female have a couple of advantages over species that need to mate.  They can reproduce when their population is low, and energy is not wasted on individuals that produce no eggs.  Most species are not parthenogenetic because in most cases the disadvantages outweigh the advantages.  Parthenogenetic species can suffer low genetic variability leading to an increase in harmful mutations.

The New Mexican whiptail lizard (Cnemidophorus neomexicanus) is an example of an all female parthenogenetic species.  The New Mexican whiptail lizard is an hybridized cross between the little striped whiptail lizard (C. ornatus) and the western whiptail lizard (C. tigris).  The New Mexican whiptail lizard produces viable eggs that all hatch to become female clones.  New lineages are created and genetic variability is established every time a western whiptail mates with a little striped whiptail.  New Mexican whiptails engage in lesbian sex.  This, of course, doesn’t fertilize the eggs, but lesbian whiptails do produce more viable eggs, probably because the sex stimulates hormone production.

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New Mexican whiptail lizards are all female clones.

Some species of vertebrates are facultive parthenogenetic species.  They normally mate with individuals of the opposite sex, but when populations are low can produce viable eggs without mating.  Komodo dragons, boa constrictors, and some species of sharks are able to switch from sexual breeding to asexual reproduction.  The offspring can then mate normally when they come into contact with males.  Other species are considered accidental parthenogenetic species.  They produce viable eggs without mating on very rare occasions.  Parthenogenetic cases have been reported for chickens, turkeys, and pigeons.

Many species of plants and invertebrates are parthenogenetic.  Unlike vertebrate parthenogenetic species which produce all females, invertebrates and plants can produce offspring that are all female, all male, or female and male.

 

Meat Eater

June 28, 2017

Steven Rinella hosts the television series Meat Eater, an hunting show airing on the Outdoor Channel every Monday at 8:00 pm.  He hunts for the right reason.  Many hunters kill animals so they can hang a trophy on the wall.  Others (more than any pro-hunting organization would ever admit) simply like to kill animals for the hell of it.  On an episode of one of Anthony Bourdain’s television series the host went hunting with a bunch of duck hunters who didn’t like the taste of duck.  Mr. Bourdain, an accomplished chef, changed their minds when he showed them how to correctly cook the birds.  But still, I don’t get it.  Why did all those men go duck hunting, if they didn’t like to eat duck?  Mr. Rinella is not like that at all.  Most Meat Eater episodes show him cooking and eating whatever animal he killed for that week’s show.

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Steve Rinella, host of the tv series Meat Eater.

Mr. Rinella first published an interesting and well written book about 10 years ago entitled The Scavenger’s Guide to Haute Cuisine.  The book is about his year long quest to produce a 45 course 3 day feast of recipes from a century old cookbook authored by the famous French chef Auguste Escoffier.  Many of the recipes used animals once popular but not commonly consumed today.  He caught stingray off the Atlantic Coast, trapped house sparrows and pigeons in the inner city, hunted wild pig in California, and helped an eel fisherman gather eels from his weir in Delaware.  He discovered he no longer enjoyed gigging for bullfrogs in Michigan.  Although this was an activity he enjoyed as a child, he admitted it grossed him out as an adult.  The frogs he killed for the feast would be his last because he decided to retire from frog-gigging.  Of course, he hunted bear, elk, mountain goat, and pronghorn out west–the main guest stars of his current television series.

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Mr. Rinella’s book is interesting and well-written.

My favorite chapter in the book was about his trip to coastal Alaska when he had the opportunity to fish for halibut.  I know I will never have a chance to visit this region and see all that wilderness and rich marine life.  By reading about his experience, I at least enjoyed some vicarious satisfaction.

Ironically, Mr. Rinella’s girlfriend at the time was a Jewish vegetarian.  He successfully converted her into a fish and shellfish eater but his feast of headcheese, pigeon cooked in pronghorn bladder, crayfish mousse, and 11 other old-fashioned dishes made her sick.  Most of the dishes he served at his Thanksgiving weekend feast of 45 courses were hits but there were misses as well.  I suppose his guests were friends close enough to give him their honest opinions.

I own a copy of Escoffier’s cookbook, but I rarely use it.  The book has over a thousand recipes, mostly consisting of various fancy ways to decorate a plate.  I am more of a blue plate special kind of cook and eater–hamburger steak and gravy, mashed potatoes, chili con carne, smothered pork chops, chicken and sausage jambalaya, stuffed cabbage, Greek salad, pumpkin pie, blueberry cobbler, etc.  Good food makes presentation irrelevant.  Escoffier doesn’t inspire me, but I’m glad it inspired Mr. Rinella to take on this project and write a book about it.  I concede Escoffier’s book is a decent primer on cooking technique.  It has helped Mr. Rinella become a really good cook.  Just look at all these delicious recipes posted on his website.

http://www.themeateater.com/section/recipe/

Mr. Rinella shares my disdain for the euphemism of the word, harvest, as a substitute for kill.  It always irks me when hunters say they are harvesting an animal.  Harvesting means a person is picking an apple or an ear of corn.  If an animal isn’t killed instantly, I’m sure the bullet or arrow piercing its nerves and flesh hurts a lot.  Hunting is killing, not harvesting.  Hunters who use the word, harvest, are dishonestly sanitizing what they do.  I’ve taken some flack for my opinion about this, but at least 1 person agrees with me.

 

Pygmy Sperm Whales of the Pliocene

May 14, 2017

The transition between the Pliocene and the Pleistocene about 2 million years ago was  marked by a major marine extinction event.  By contrast there was far less faunal turnover on land.  Many species of whales that no longer exist swam in Pliocene oceans.  Paleontologists recently analyzed fossil whale ear bones excavated from sites in Florida and North Carolina and determined at least 2 morphotypes of pygmy sperm whales occurred in the Atlantic Ocean during the Pliocene.  These specimens may represent different species or size variations within a single species.  Scientists can’t make a certain determination based on just the ear bones.  Extant bottle-nosed dolphins ( Tursiops truncatus ) occur as 2 different morphotypes in the Atlantic Ocean. Deep sea dolphins are larger and more powerful than near coastal dolphins, and dolphins living in estuaries and tidal rivers don’t even interbreed with dolphins living off the coast.  Yet, these 3 separate populations are considered the same species.  The extinct species of pygmy sperm whales may have also occupied different habitats.

The pygmy sperm whale fossils came from phosphate mines in Florida and spoil piles originating from Lee Creek Mine in North Carolina.  The Florida site is thought to yield fossils that are 5-4.7 million years old, and fossils from Lee Creek Mine are estimated to be between 4.8-3.1 million years old.  Ear bones of the larger morphotype were found at both sites, but the smaller morphotype was found exclusively in Florida.

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Pygmy sperm whales are barely bigger than bottle-nosed dolphins.

Dwarf Sperm Whale Ear

Dwarf sperm whale ear bone.  The dwarf sperm whale is not the same species as the pygmy sperm whale.

The extant pygmy sperm whale ( Kogia breviceps ) grows to 11 feet long and feeds upon squid, octopus, and shrimp.  They release a kind of ink from their intestines when they are attacked by large sharks or killer whales.  I think this defense strategy is unknown among any other species of mammal.  Pygmy sperm whales are related to dwarf sperm whales ( K. sima ), and the more famous hero of the novel, Moby Dick ( Physeter macrocephalus ).  Like their larger cousin, pygmy sperm whales locate their prey using echolocation.

The sperm whale family had more relatives during the Pliocene, but those extinct species are so little known and so little evidence of them remains that we will probably never know what made each unique.

Reference:

Velez-Jaurbey, Jorge; A Ward, and C. Pimento

“Pygmy Sperm Whale (Odostecenti, Kogiidae) from the Pliocene of Florida and North Carolina”

Journal of Vertebrate Paleontology 2016

 

Panthera atrox: the 1007 Pound Giant Lion

January 31, 2017

An extinct species of lion ( Panthera atrox ), similar but larger than the extant African lion ( P. leo ), occupied open habitat in North America from California to South Carolina and Florida for over 300,000 years.  The American lion evolved from the also extinct Eurasian cave lion ( P. spelea ) when the ice sheet that covered Canada isolated the 2 populations from each other. The 2 species never re-connected during interglacials because extensive spruce forests, an unfavorable habitat for lions, grew between them.  Fossil evidence of large carnivores is relatively uncommon because their populations are smaller than those of their prey. But there are 2 fossil sites that preserved a considerable number of carnivores due to unusual circumstances, and scientists were able to collect enough lion specimens from them to study and compare the anatomy of the species as a whole.  The 2 sites are Natural Trap Cave in Wyoming and the Rancho La Brea Tar Pits in California. Scientists estimated average body size and the results were astounding.

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Hercules is the world’s largest cat. It is a 922 pound lion x tiger hybrid that lives at the Myrtle Beach Safari Preserve in South Carolina.  It is smaller than the estimated size of the largest known fossil specimen of North American lion, an extinct species that formerly lived coast to coast.

The largest male Panthera atrox specimen came from an animal that was estimated to weigh 1007 pounds, though the average male weighed 544 pounds.  The largest female American lion was estimated to weight 577 pounds, while the average was 390 pounds.  By contrast the average extant African male lion weighs 392 pounds.  This means the average female American lion was about the size of the average male African lion.  The large difference in size between the sexes, known as sexual dimorphism, suggests American lions lived in social prides like their African cousins.  An 1000 thousand pound lion would be too large and slow to hunt successfully enough to sustain its bulk, but instead relied on the smaller more agile females to secure all the bison, horses, and camels he required.  A large pride could probably even take down a full grown mammoth.

The large size of the males helped them fend off other male lions that wished to usurp their mating rights and kill their offspring.  The enormous powerful males could also aid in protecting the pride’s kills from competing carnivores such as bears, saber-tooth cats, and dire wolves.  American lions had longer legs and bigger braincases than African lions, so they were faster runners and smarter as well.  P. atrox really was a king of the beasts.

Reference:

Wheeler, H.T; and G.T. Jefferson

Panthera atrox: Body Proportions, Size, Sexual Dimorphism, and Behavior of the Cursorial Lion of the North American Plains.”

In Papers on Geology, Vertebrate Paleontology, and Biostratigraphy in Honor of Michael O. Woodburne edited by L.B. Albright III

Museum of Northern Arizona Bulletin 65