Archive for the ‘Pleistocene Mammals’ Category

How Long did it Take Humans to Wipe Out American Megafauna?

October 15, 2021

20 years ago, a computer simulation determined low levels of human hunting could cause the extinction of Pleistocene megafauna within a 1,640 year time frame. This simulation has held up well since the results were first published. A recent study of sedimentary data from Lake Llaviucu, Ecuador determined most of the megafauna in this region became extirpated 1,800 years after humans first entered the area. 1,800 years is remarkably close to 1,640 years. Another study, this one of a site in Patagonia, determined megafauna were extirpated in that region between 1000-2000 years after first human contact–also remarkably close to the computer simulation.

Locations of the data obtained for the below referenced study. Scientists dredged cores of sediment from beneath Lakes Llaviucu and Palicacocha in Ecuador. They used pollen composition, charcoal abundance, and dung fungus spore concentrations to determine the presence of humans, not environmental change, caused the extirpation of megafauna in this region. Image from the below referenced study by Raczka et. al.
Graph showing pollen composition, charcoal abundance, and dung fungus (sporomiella) concentrations. Dung fungus abundance is a proxy for the presence of megafauna; charcoal concentrations are a proxy for human presence because people set fires. People were present, but the environment did not change. It was a paramo grassland before people entered the region, and it still was a paramo grassland when megafauna became extinct in this region. Image also from the below referenced study by Raczka et. al.
Lake Llaviucu in Ecuador along with a llama. A glacial moraine dams a stream, thus creating this lake. Photo from Travel Ecuador.
A paramo grassland. Photo from the Missouri Botanical Garden. This region has been a paramo grassland for 16,000 years. Megafauna became extinct here about 12,800 years ago…1800 years after humans colonized the region. There was no change in the environment.

Scientists analyzed the pollen composition, charcoal concentration, and dung fungus spore concentration from a sedimentary core taken at Lake Llaviucu. The pollen composition provides information about the local environment. The area was under a glacier until ~18,000 years ago. After the glacier receded it was replaced by paramo grassland, an environment dominated by tussock grasses, rosette plants, and evergreen shrubs. Tropical cloud forests occur at lower elevations and plants from this environment contribute to the pollen rain. Charcoal concentrations are used as a proxy for human presence. Lightning strikes, a natural cause of fires, are extremely rare at this locality, so charcoal most likely came from human-set fires. Charcoal became common at this site about 14,600 years ago. Dung fungus spore abundance is a proxy for megafauna populations. Dung fungus declined in abundance 12,800 years ago. This is when populations of stegomastodons, horses, and ground sloths likely disappeared from the region. The core taken from this lake was 36 feet long and radiocarbon dates ranged from 16,200 years BP at the lowest part of the core to 9,000 years BP at the highest. The finding is consistent with similar studies at other sites in the Americas.

Lake Llaviucu is located in El Cajas National Park. Though most of the megafauna is gone, there are still some species of large mammals left here including llamas, mountain tapir, deer, spectacled bear, and cougar. The park is also home to 157 species of birds, and it is the Andean condor’s last stand. I’d love to visit the paramo grasslands and tropical cloud forests, but alas it is too far away.

Reference:

Alroy, John

“A Multi-Species Overkill Simulation of the End Pleistocene Megafaunal Extinction”

Science 292 (5523) 2001

Raczka, M. et. al.

“A Human Role in Andean Megafaunal Extinction?”

Quaternary Science Review 205 2019

Grayson’s and Meltzer’s Case Against Overkill would get Thrown out of a Court of Law for Perjury

I was listening to National Public Radio the other day, and they were interviewing a paleontologist who was excavating the bones of extinct Pleistocene megafauna. I didn’t catch his name or the name of the fossil site, but he was certain overhunting by humans caused the extinctions. For balance they also interviewed Meltzer, an archaeologists from SMU, who believes environmental change, not humans, caused the extinctions. About 20 years ago, he co-authored a series of illogical papers with Donald Grayson, an anthropologist, in an attempt to debunk the theory that man caused the extinction of Pleistocene megafauna. They are both a couple of dishonest shmucks. They are not paleo-ecologists. They are an archaeologist and an anthropologist. They know nothing about paleo-ecology. On the radio Meltzer simply repeated the same illogical arguments he made 20 years ago, and he ignored the overwhelming number studies that have since been published in support of an human role for the extinctions. A few years ago, Grayson published a book with a chapter about extinctions. He deliberately misrepresented the findings of a paper that ruled out environmental change as a cause of megafaunal extinctions. He suggested the results were the opposite of what the authors of the study concluded. (See: https://markgelbart.wordpress.com/2017/01/23/donald-graysons-disingenous-case-against-overkill/ ) In a court of law a judge will throw out a case, if a witness perjures himself. Grayson’s and Meltzer’s case against overkill would get thrown out for perjury. Incidentally, I informed Grayson of the above linked article. He refused to respond.

Cougars (Puma concolor) Control Feral Horse (Equus caballus) Populations in Some Environments

September 3, 2021
Photo of Cougar feeding on a horse from The Wildlife Society

President Teddy Roosevelt called the cougar that “horse-killing cowardly cat.” Though Teddy Roosevelt was a progressive President for his time, I think some of his opinions and attitudes were highly distasteful. He was a war monger and a sadist. He went on a safari to Africa and slaughtered thousands of animals, using the excuse that he was sending specimens back to an American museum. Cougars kill for food, but Roosevelt was slaughtering thousands of animals from a distance with an high-powered rifle under the false guise of obtaining scientific information. I think he did it because he enjoyed being a bloodthirsty killer. I respect the bravery of a cougar far more than anything Roosevelt ever did as an outdoorsman. Cougars are 1 of the few solitary carnivores that regularly attack prey larger than themselves.

There is no doubt cougars kill horses, but Steve Rinella, a Trumpanzee with an hunting and fishing show on the Outdoor Network, disputed a New York Times column written by Dave Phillipps, suggesting cougars could control feral horse populations. Phillips refused to appear on Rinella’s podcast, and Rinella seemed to relish how another expert had proven the author of the column wrong. He’s not wrong. A recent study determined cougars could control feral horse populations in sagebrush environments. Scientists studied 21 radio-collared cougars–13 in the Great Basin region of Nevada and 8 on the Sierra Nevada range. They counted 820 predation events and learned that in the Great Basin region horses made up 60% of the cougars’ diet while mule deer just made up 29% of their diet. On the Sierra Nevada range, mule deer made up 91% of their diet. Cougars hunted horses in sagebrush environments quite often, but rarely in mountain environments. In the Great Basin individual cougars killed an horse about once every 2.5 weeks. Another study looked at cougar prey on the Pryor Mountains. Here, cougars killed no horses and their primary prey was mule deer, though bighorn sheep made up 9% of their prey. 1 individual female cougar specialized in preying upon bighorn sheep, but most cougars preferred deer. I think horses are not an important part of the cougar diet in the Pryor Mountains because there are less than 200 of them there, and they are located in an area with no cougars.

Of course, cougars hunt horses. During the Pleistocene cougars co-existed with horses over the span of 2 continents for hundreds of thousands of years. I’m sure there were certain ancient environments where horses were the most available prey species. Horses are well adapted to arid grasslands, and during the Pleistocene were more common than deer in this type of environment. Cougars would have been competing with dire wolves, giant lions, and saber-tooths in open areas, and they likely were more common in woodlands or forest edges. But they may have held their own in some locations where horses and competing carnivores were abundant, depending upon ecological conditions. Incidentally, the Pleistocene cougars that lived in North America were not directly ancestral to cougars that live on this continent now. They were an extinct ecomorph that grew slightly larger than modern cougars and may have had spotted fur. According to genetic evidence, all modern North American cougars descend from a population originating in eastern South America about 10,000 years ago. Strange as it may seem, this population completely replaced the Pleistocene ecomorph.

Horses originated in North America and lived here for millions of years, until man wiped them out. People who claim feral horses harm the environment are full of shit. Horses make trails, defecate all over the place, and graze down vegetation…just like they did for millions of years. Horses recolonized North America, and this recolonization is no different from when wildlife managers re-introduce endangered species to lands where they had previously disappeared. There are only about 83,000 feral horses in North America today compared to tens of millions of cattle, yet cattle ranchers and do-gooder environmentalists would dishonestly lead people to believe horses are the problem, not the cattle. I call bullshit.

References:

Blake, L.

“Foraging Ecology of Cougars on the Pryor Mountains of Wyoming and Montana”

Utah State Graduate Thesis 2014

Andreason, A.; K. Stewart, W. Longled, J. Berkman

“Prey Specialization in Cougars on Feral Horses in a Desert Environment”

Journal of Wildlife Management July 2021

My Pleistocene Mammal Checklist of East Central Georgia 36,000 Years BP Revised

August 13, 2021

8 years ago, I wrote a blog entry listing the exact species of mammals I thought probably lived in east central Georgia 36,000 years ago. I chose this time because it was the most recent period when climate was similar to today’s climate, coinciding with the last time when man was probably absent. I wondered what mammals would live in an environment untouched by man but with a similar climate. My list was an educated guess because there is only 1 Pleistocene-aged fossil site in this region, though there are some to the immediate north, south, and east. This time period was an interstadial–a warm wet period between colder drier Ice Ages. Pollen evidence suggests oak tree populations expanded. So I assumed the ecosystem was a mix of open oak woodlands, some grasslands, wetlands, and relict arid scrub environments persisting from the previous stadial. Since I wrote this blog, new information has come to light, and my list needs to be revised. Before I started to write this, I didn’t realize I had already edited some of the changes into my original article. (See: https://markgelbart.wordpress.com/2013/12/27/if-i-could-live-during-the-pleistocene-part-xii-my-mammal-checklist/ )

The 9-banded armadillo is an addition to my list. 9-banded armadillos have recently recolonized the region, but until a few years back scientists didn’t realize this species had also lived in southeastern North America during the Pleistocene. Their fossils had been confused with those of the beautiful armadillo, a different extinct species that was about twice as big. But analysis of genetic material shows that both co-existed over the same range.

On my original list I put question marks next to species that I was unsure lived in the region during this time period. Fox squirrels are 1 that should have a question mark next to it. There is no evidence in the Florida fossil record of fox squirrels until very late during the Pleistocene ~12,000 years BP. However, fox squirrel remains have been found in a Georgia cave that date to the LGM ~21,000 years ago. They may be a late invader of southeastern North America, but on the other hand they could just have been local in distribution and perchance never left remains in fossil sites. By contrast gray squirrels are commonly found in regional fossil sites. Perhaps east central Georgia was an area where fox squirrels occurred 36,000 years ago and from where they expanded into the rest of the south, but the dearth of fossil sites explains why this is unknown.

On my original checklist I included 2 species of horses, but it seems likely there was only 1–Equus caballus. Fossils of the pseudo-asses that date to the late Pleistocene are restricted to the west. The pseudo-asses did occur in southeastern North America during the Pliocene and early Pleistocene, but by 36,000 years ago they were not living in the region.

I included elk on my original checklist, but genetic evidence suggests this species did not colonize North America until about 15,000 years ago. No radiometrically dated remains of elk on the continent prior to that date have ever been found. Unless there was an extinct lineage of elk ranging here, I don’t think they lived in the region. White-tailed deer were likely the most common species of deer in the region then, just like today. However, I do believe woodland caribou and the extinct stag-moose did occasionally range into the region. Fossil remains of both species have been found at this latitude. They were probably more common in the region during Ice Ages, but I think it seems likely a few stragglers did wander into the region during interstadials. After all, this was unchecked wilderness. Some caribou herds likely migrated haphazardly, and sometimes they wandered into the region.

I think herds of caribou wandered into east central Georgia even during interstadials.

Scientists identify the remains of a medium-sized canid as coyote from fossil sites that are known to date throughout the late Pleistocene. However, genetic evidence suggests coyotes diverged from the population of gray wolves that crossed the Bering Land Bridge into North America just 20,000 years ago. So what were these coyote-like canids? I think they are an unnamed extinct species anatomically difficult to discern from modern day coyotes. This species likely played a similar ecological role. On my list Canis latrans should be changed to unnamed extinct canid.

Dire wolves and jaguars were likely the most common large predators in the region. Giant lions and saber-tooths may have existed in low numbers here. The former were more common in the more open grasslands to the south of the region. But I think bears were by far the most common carnivores. If a person could travel back in time and take a walk in the woods of this region, it would be impossible not to run into a bear. Bears are omnivores and can breed and reproduce even when there are low populations of other large mammals. Grizzly-sized black bears, Florida spectacled bears, and giant short-faced bears all roamed the region then.

I still think most of the other famous Pleistocene megafauna occurred in the region, but some may have been transitory. I think Jefferson’s ground sloth and Harlan’s ground sloth were year round residents as were stout-legged llamas and long-nosed peccaries. Herds of long-horned bison roamed around looking for fresh pasture. Mammoths possibly passed through during annual migrations. And mastodons moved up and down the river valley bottoms.

Horn Size Comparison Between Bubalus arnee and Bison latifrons

July 16, 2021

Some species of extant megafauna demonstrate how impressive similar extinct species were. Asian water buffalo (Bubalus arnee) weigh up to 2600 pounds, and their horn span averages 3 feet long. The individual in the below photo has an horn span of about double the size of the average. The largest known horn span of an Asian water buffalo was from a specimen shot in 1955–it had an astounding horn span of 13 feet 10 inches. The extinct long-horned bison (Bison latfrons) had horn spans up to 7 feet long, but it seems likely the largest individuals had horn spans even longer than the record specimen of Asian water buffalo shot during 1955. Long-horned bison are estimated to have reached weights between 2700-4400 pounds–significantly heavier than Asian water buffalo–and if these estimates are accurate, some individuals probably had horn spans exceeding 14 feet long.

Asian water buffalo (Bubalus arnee). Their horn span averages 3 feet, but this animal has an horn span that is close to twice that long. I found this photo on Twitter. I don’t know who took it.
I took this photo of a Bison latifrons specimen at the Georgia College Museum in Milledgeville, Georgia. This specimen was found near Brunswick, Georgia and dates to 24,000 years ago. This species evolved into Bison antiquus during the Last Glacial Maximum. B. antiquus evolved into modern Bison (B. bison) after the end of the last Ice Age.

The Asian water buffalo has been classified as endangered since 1986. There are only 4000 left. They are found in small herds in 8 protected areas in India, 1 in Nepal, 1 in Bhutan, 1 in Thailand, and 1 in Cambodia. They are thought by many to be the ancestors of domesticated water buffalo, an animal used for pulling plows before the era of mechanization. Asian water buffalo prefer to live in swamps and marshes, and their hooves are wide and don’t sink in muddy ground, giving them superior performance in farm labor compared to a plain old ox. They also produce a richer milk than cows, and cheese-makers use their milk to make Mozzarella. Domesticated water buffalo have escaped from captivity in Australia, parts of Asia, Argentina, and Bolivia where they thrive on grass, sedges, fruit, bark, and twigs in wetlands. A species of European water buffalo became extinct about 10,000 years ago.

The ancestor of the long-horned bison crossed the Bering Land Bridge and colonized North America a little less than 300,000 years ago, marking the beginning of the Rancholabrean Land Mammal Age. They inhabited open woodland and prairie. Their long horns were a defense against big cats such as saber-tooths, giant lions, and jaguars (just like water buffalos use their horns to fend off tigers and lions). During the Last Glacial Maximum ((~21,000 years BP-~15,000 years BP) long-horned bison evolved into a smaller animal with shorter horns known as B. antiquus. This was likely in response to reduced quality of food and water sources. Following the arrival of man in North America, B. antiquus evolved into the even smaller but more mobile and migratory modern bison (B. bison). Instead of long horns and large bodies to battle big cats, bison needed longer legs, so they could run away from wolf packs and man.

Arthritic Glyptodonts

July 9, 2021

I am lucky so far. I am 59 years old and don’t feel arthritic yet, but my father was about my age when he first suffered from arthritis. The incurable disease forced him to give up playing tennis because his hand hurt too much when he tried to return a shot. About 50 million adults and 300,000 children suffer from arthritis. There are over 100 types of arthritis. The 4 most common include degenerative, infectious, inflammatory, and metabolic. Degenerative arthritis is caused by cartilage wearing away so that 2 different bones rub against each other at the joint. Bacteria cause infectious arthritis, and inflammatory arthritis is the result of the immune system turning against itself following an infection. Metabolic arthritis is caused by uric acid build up. This is the kind my dad had, and he also used to suffer terrible attacks of gout–a related condition.

Man isn’t the only animal that suffers from arthritis. Other primates, elephants, bears, and extinct ground sloths are known to be susceptible to the disease. Paleontologists examining bones of extinct glyptodonts found evidence of arthritic joints. Glyptodonts are related to armadillos. A recent genetic study found their closest living relative was the tiny pink fairy armadillo–an ironic discovery because fairy armadillos are so small, and glyptodonts weighed several tons. However, glyptodonts diverged from armadillos about 35 million years ago. The main difference between armadillos and glyptodonts is the shell. Armadillo shells in most species are flexible, and they can curl up in a ball when threatened. Glyptodonts had stiff turtle-like shells. The arthritic glyptodont bones were found in a limestone cave near Lajeda de Ecole, Brazil. Glyptodonts ranged throughout South America and into the southern parts of North America including coastal Georgia. The arthritic glyptodont specimen found in Brazil suffered from calcium pyrophosphate disease, a complication of spondyloarthropy. This disease is known as false gout because it is similar to gout, though the physiological cause differs. The specimen’s arthritis was in its arm and leg joints.

3 different species of glyptodonts compared to an average-sized man. I found this image on google. I don’t know who the original creator was.
Glyptodont joints with arthritis. Image from the below referenced paper.

Arthritic glyptodonts may have been more vulnerable to predators. When attacked, glyptodonts quickly turned around and swung their tails which in some species were clubbed. A glyptodont slowed by arthritis may have been too sluggish to swing their tail in time. Scientists found 1 specimen of arthritic glyptodont with gnaw marks from an extinct dog known as Protocyon trogylodytes. This predator may have killed the aged glyptodont or perhaps it scavenged an animal that died of old age.

References:

Aurauj-Junior, H. ; et. al.

“Overlapping Paleoinchnology, Paleoecology, and Taphonomy: Analysis of Tooth Traces in Late Pleistocene-Early Holocene Megafaunal Assemblage of Brazil and Description of New Ichnology in Hard Substrate”

Paleogeography, Paleoclimatology, and Paleoecology 468 2017

Barbosa, F. ; et. al.

“Arthritis in a Glyptodont (Mammalia, Xenartha, Cintulata)”

Plos One Feb 2014

Pleistocene Megaherbivores of India

March 25, 2021

388 species of land mammals occur in India today, including 15 species of flying squirrels, 20 species of bovids, 18 species of deer, 16 species of cats, 19 species of monkeys, and 3 species of apes.  The diversity of habitats in India from high mountains to desert plains with subtropical forests and mangrove swamps in between supports this great variety of mammals.  Africa has 1100 land and marine species of mammals and Pleistocene North America had 540, but they are whole continents.  India is just a subcontinent.  Compared to North America but like Africa, India didn’t suffer many late Pleistocene extinctions.  However, there were a few notable species that became extinct or extirpated in India.

Gelada baboons (Theropithecus gelades) today are restricted to the Ethiopian Highlands, but fossil evidence from the Billasugrun Cave Complex showed they formerly ranged into India.  Ostriches also formerly extended their range into India during the Pleistocene, but no longer occur there.

Screenshot (186)

Gelada baboons are restricted to the Ethiopian Highlands today, but during the Pleistocene their range extended into India.

Today, Asiatic elephants still live in India, but during the Pleistocene 2 additional species of elephants occurred in India–the Asian straight-tusked elephant (Paleoloxodon namadicus) and stegodon (Stegodon namadicus).  The former may have been the largest land mammal to ever live on earth.  Both species went extinct about 30,000 years ago when men began using projectile weapons.

Palaeoloxodon namadicus is a prehistoric straight-tusked elephant that ranged through Pleistocene Asia, fro… | Prehistoric animals, Extinct animals, Ancient animals

Scientists think the Asian straight-tusked elephant may have been the largest land mammal ever.  It became extinct in India soon after humans began using projectile weapons ~30,000 years ago.

What are the differences between Stegodon and Palaeoloxodon? - Quora

Stegodon namadicus.  The fossil record suggests it was formerly more abundant than the Asiatic elephant.  It too became extinct about the time man began using projectile weapons.

The pygmy hippo (Hexaprotodon) lasted in India until about 16,000 years ago.  There still is plenty of available habitat for pygmy hippos in India today, so man must be responsible for the disappearance of this species.  An horse (Equus namadicus) became extinct in India.  I can’t find much about this species, and I think it may have been the same species as the modern horse.  The wild ancestor of modern cattle (Bos namadicus) also vanished from India during the late Pleistocene, but its domesticated descendants are extremely abundant now.

File:Hexaprotodon.liberiensis-ZOO.Jihlava1.jpg - Wikimedia Commons

African pygmy hippo.  A species of pygmy hippo lasted in India until about 16,000 years ago when humans wiped them out.

Gaur - Description, Habitat, Image, Diet, and Interesting Facts

The gaur along with Asiatic elephants and Indian rhinos are still extant but endangered in India.

Scientists hypothesize India suffered fewer end Pleistocene extinctions than elsewhere because the animals there slowly co-evolved with man and learned to be wary of us.  They think this allowed for a robust population network in climatic refugia that could then rebound following local extirpations.  While this might be partially true, I have a different hypothesis.  I propose that in India (and Africa) tropical diseases and tribal warfare kept human populations relatively low.  Large tracts of land remained uninhabited for centuries.  These were the refugia that allowed animal populations to rebound and replenish regions with diminished or extirpated populations.  The Hindu religion’s reverence for life originated at least 6300 years ago and may be an additional factor in the persistence of abundant wildlife on the Indian subcontinent.  When India’s population of humans eventually did increase, the Hindu religion prevented the wonton slaughter of wildlife that plagued other regions such as China where tigers and elephants have been wiped out.

References:

Jukar, A.; S. Lyons, P. Wagner, M. Uhen

“Late Pleistocene Extinctions in the Indian Subcontinent”

Palaeogeography, Palaeoclimatology, Palaeoecology 562 (15) 2020

Roberts, P.; et. al.

“Continuity of Mammalian Fauna over the Last 200,000 Years in the Indian Subcontinent”

PNAS 111 (16) 2014

Ancient Bear Hybridization

March 4, 2021

It’s always surprising when studies of an animal’s genetic history yield unexpected results, and the latest look at spectacled bear (Tremarctos ornatus) DNA is no exception.  The study (referenced below) examined 3 specimens of the extinct giant short-faced bear (Arctodus simus) and 1 specimen of the extinct Arctotherium sp. and compared their genetics with that of the extant spectacled bear.  The giant short-faced bear specimens came from the Yukon and Alaska and dated to ~47,000 years BP and ~24,000 years BP.  The Arctotherium specimen came from Chile and dated to 12,000 years BP.  Although Arctotherium anatomically resembled A. simus, results of the study determined the 2 species never interbred.  The giant short-faced bear was a North American species, and Arctotherium was a South American species, but their ranges did overlap in Mexico.  However, the study indicated the extinct Arctotherium did hybridize with the extant spectacled bear during the late Pleistocene.  Both are South American species  and their ranges did overlap extensively.  This is a surprising result because scientists estimate the ancestor of the spectacled bear diverged from the ancestor of Arctotherium about 3.6 million years ago, and they were quite distinct species.

ADW: Tremarctos ornatus: PICTURES

Spectacled bear–the only extant tremarctine bear.  Genetic evidence from a new study suggests they occasionally interbred with the extinct Arctotherium bears during the late Pleistocene and they also interbred with the common ancestor of modern grizzly and black bears during the Pliocene.

Arctotherium Angustidens : Naturewasmetal

Artist’s depiction of the extinct Arctotherium.

The study produced an additional surprising result, but before I discuss this I need to digress and explain the 2 lineages of bears.  Ursine bears (black, grizzly, polar, Asiatic black, sun, and sloth) diverged from tremarctine bears about 10 million years ago.  The spectacled bear is the only tremarctine bear still extant, but during the late Pleistocene there were 3 additional species including the giant short-faced, Arctotherium, and the Florida spectacled bear (T. floridanus).  Results of this study suggests the ancestor of the South American spectacled bear did hybridize with the common ancestor of the black bear and grizzly bear.  The ancestor of black bears diverged from the ancestor of grizzly bears at least 1.5 million years ago, so this hybridization event likely occurred during the Pliocene.  The giant short-faced bears and Arctotherium never hybridized with ursine bears, but different species of ursine bears hybridized with each other numerous times.

In the future it would be interesting to see the results of a genetic study of T. floridanus.  The Florida spectacled bear ranged throughout southeastern North America during the Pleistocene and it shared the range with black bears.  Did these 2 species ever hybridize?

Reference:

Salis, A.; et. al.

“Ancient Genomes Reveal Hybridization between Extinct Short-faced bears and the Extant Spectacled Bear (T. ornatus)

BioRxiv Feb 2021

https://www.biorxiv.org/content/10.1101/2021.02.05.429853v1

Some Pleistocene caribou (Rangifer tarandus) Gorged on Seaweed

February 11, 2021

Seaweed is an healthy dietary supplement for ruminants (animals that chew their cud).  Sheep in Scotland, reindeer in Norway, and caribou living along the coast of Alaska eat seaweed that washes up on the shore.  However, seaweed is seldom more than 5% of their diet.  If a caribou or sheep eats too much seaweed, they ingest too much salt and suffer diarrhea. A diet of mostly seaweed is not optimal.

Scientists recently analyzed a 45,000 year old caribou antler found on Haida Gwaii Island located off the coast of British Columbia.  They determined through an analysis of carbon and nitrogen isotopes in the amino acids that seaweed made up between 23%-41% of this individual’s diet.  The authors of this study think weather conditions forced this caribou into a suboptimal diet.  Normally, caribou feed upon birch and willow twigs and leaves, sedges, and mushrooms during summer; and lichen and dried sedges during winter.  They are capable of removing snow cover with their hooves, but they have difficulty breaking through icy snow when it covers their feeding grounds.  Apparently, icy snow covered this caribou’s prime feeding grounds, and it had to subsist on kelp washed on shore.  This caribou did live during a cold stage of the Wisconsinian Ice Age.

Image result for Haida Gwaii map

Map of Haida Gwaii Island, location of the 45,000 year old caribou specimen analyzed by scientists.  During the Ice Age the island was larger.  The coast of British Columbia and Alaska served as a glacial refuge for western caribou because most of their present day range was under glacial ice.  Caribou also roamed as far south as South Carolina, Georgia, and Alabama during the Ice Age.

Image result for caribou eating seaweed

Svalbard reindeer feeding upon washed up kelp.  Reindeer are the same species as caribou.

Image result for caribou

North American caribou

Image result for kelp washed ashore

Kelp washing up on shore was an important item in the diet of at least 1 caribou 45,000 years ago.

Image result for Cladonia rangerfina

Cladonia rangerfina–a lichen.  This is a common winter food for caribou over much of their range.  Lichen are a symbiotic organism–a fungus with algae and/or cyannobacteria living in it.

Caribou roamed far down the eastern seaboard during the Ice Age.  Caribou fossils have been found as far south as Charleston, South Carolina, and their bones are often dredged up in fishing nets off the coast of North Carolina.  Caribou bones have also been excavated from caves in north Alabama and north Georgia.  Caribou probably migrated seasonally in eastern North America, and the route of some herds likely included an area along the Atlantic Coast that is now ocean but was dry land during the Ice Age.  I wonder if eastern caribou some times ate seaweed as well.  There are specimens that scientists could study to answer this question.

I also wonder what else caribou ate when they lived farther south during the Ice Age.  Lichen is a present day favorite food, and there are 17,000 different species of lichen worldwide.  Lichens are symbiotic organisms consisting of a fungus with algae and/or cyannobacteria.  The fungus gets nutrients from the woody or rocky substrate but also gets nutrients from the photosynthesis of the algae or cyannobacteria.  Nevertheless, I don’t think lichen was an important food source for eastern Ice Age caribou.  There were probably better quality foods available in the richer woodlands and grasslands of the east.

Reference:

Kubiak, C; R. Mathewes, J. Grimes, G. Biesen, and M. Rochester

“Evidence of a Significant Marine Plant Diet in a Pleistocene Caribou from Haida Gwaii, British Columbia”

Palaeogeography, Palaeoclimatology, and Palaeoecology 564 Feb 2021

Middle Pleistocene Man (Homo heidelbergensis)

January 29, 2021

Many late Pleistocene animals evolved from middle Pleistocene ancestors that were different enough to be considered separate species.  Columbian mammoths (Mammuthus colombi) evolved from the southern mammoth (M. meridionalis), a shorter elephant with straighter tusks. Jefferson’s ground sloth (Megalonyx jeffersoni) evolved from Wheatley’s ground sloth (M. wheatleyi), and Smilodon fatalis evolved from the more lightly built S. gracilis, among many other examples.  The same is true for humans.  Both Homo sapiens and H. neanderthalis evolved from H. heidelbergensis, also known as Heidelberg man after discovery of the first specimen in Heidelberg, Germany during 1907.  Genetic evidence suggests modern humans diverged from Neanderthals between 750,000 years BP-550,000 years BP.  The population of Heidelberg man that lived in Europe evolved into H. neanderthalis, while the population of Heidelberg man that lived in Africa evolved into H. sapiens.  (The poorly known Denisovans diverged from Neanderthals.) Fossil evidence of Heidelberg man dates to between 600,000 years BP-300,000 years BP, though undoubtedly it occurred earlier than the fossil evidence indicates.  The oldest evidence of humans in Europe dates to 800,000 years ago and was found in Spain, but these specimens are considered an extinct sister species of Heidelberg man known as H. ancessor.

Homo Heidelbergensis: Forbears of Homo Sapiens - The Human Journey

Artist’s depiction of Homo heidelbergensis.  They were about the same height as modern men and had the same average brain capacity, but their jaws were distinctly different.

New insights on the wooden weapons from the Paleolithic site of Schöningen - ScienceDirect

The Schoningen spears, 330,000 year old projectile weapons used by Homo heidelbergensis.  They were found in a strip mine in Germany.  Archaeologists found 9 spears, 1 lance, a stick pointed on both ends, and a burned stick along with the remains of butchered horses next to a lakeshore.

Heidelberg man evolved from H. erectus.  Heidelberg man had a more human-like face and a larger brain capacity (averaging 1200 cc compared to 973 cc).  They had the same average brain size as modern day humans, and the main difference between the 2 is the shape of the jaw which was distinct.  Heidelberg man was the first species of human to colonize regions with cold climates.  To survive in harsher climates, they evolved to eat more meat.  In Europe this diet included elephant, rhino, bear, deer, boar, and horse; and in Africa they ate antelope and zebra.  They surely ate many different kinds of plants, but nothing is known of the vegetal part of their diet.  Heidelberg man had control of fire and used tools such as stone hand axes and wooden spears. In 1994 nine spears made of spruce wood were found in a German strip mine, and they dated to 330,000 years BP.  They are known as the Schoningen spears, and they were found associated with butchered horse bones.  Rapid rise of a lake level covered all this evidence in sediment and helped preserve it.

I have no doubt Heidelberg man could speak, though a minority of scientific opinion believes they could not.  The hyoid bone, important for speech, is well developed as are the middle ear bones used for understanding speech.  There is also evidence for right brain/left brain lateralization–one side of the brain is more dominant.  Brain lateralization suggests a brain used to speak and understand speech.  Heidelberg man hunted large mammals, an activity requiring cooperative hunting and therefore speech.

Specimens of Heidelberg man have been found in sites located in Germany, England, France, Greece, India, Zambia, Kenya, Ethiopia, and South Africa.  I tried to find out exactly how many specimens have been discovered worldwide, but as far as I can determine no study has catalogued them all.

Heidelberg man likely occurred in low population numbers, fluctuating with boom and bust climatic conditions, and whole tribes often perished  when important members died.  One site in Germany where Heidelberg remains were found also yielded bones of saber-tooths (Homotherium), lions, leopards, hyenas, bear, elephant, red deer, and horse.  Unlike modern humans, Heidelberg man didn’t always win in competition with the predators they shared the landscape with.

Reference:

Schoch, W.; G. Bigga, W. bohner, P. Richter, and T. Terberger

“New Insights on the Wooden Weapons from the Paleolithic Site of Schoningen”

Journal of Human Evolution 89 December 2015

Did Some Species of Giant Ground Sloths Live in Herds?

January 22, 2021

At least 22 giant ground sloths (Eremotherium laurillardi) perished in a pond polluted with their own feces over 18,000 years ago.  Scientists excavating this site found 667 vertebrate bones of which 575 were identified as belonging to Eremotherium.  These included the remains of at least 16 adults, 6 subadults, and 1 juvenile.  Fossil feces and gut contents were found alongside the bones.  The site, known as Tanque Loma, is located in Southwestern Ecuador.  Eremotherium was the largest of the extinct ground sloths, roughly the size of an African elephant, and they ranged from South America into southern North America, though they disappeared from the northern part of their range during the Last Glacial Maximum when the climate got too cold for them there.  Eremotherium bones show up in most coastal fossil sites in Georgia.  Fossil sites mostly composed of Eremotherium bones occur in Florida, Ecuador, Brazil, Mexico, and Uruguay; and the circumstances of these mass death sites may be the same.  Large groups of Eremotheriums, attracted to shrinking water holes during droughts, congregated there until they poisoned the water with great quantities of their feces.  The entire group then died within a few days, explaining the mass accumulation of mostly 1 species.  Modern hippos in Africa often suffer the same fate today.

Eremotherium Foot and Hand

Illustration of Eremotherium along with other Pleistocene animals.  Painting by the late Charles Knight.  Eremotherium may have been less hairy, like humans and elephants.  They were also larger than this illustration indicates.

Anthrax May Have Killed 100 Hippos in Namibia

Mass hippo deaths can occur when they contaminate the water they live in with their own feces.

Some scientists think the occurrence of different age groups at these mass death sites indicates Eremotherium lived in herds.  I doubt this can be determined.  It seems more likely they were simply attracted to the same resource.  Caves accumulate ground sloth remains as well because they were a resource that provided shelter for an animal that had difficulty controlling its body temperature.  Water holes and food items were resources that attracted ground sloths to the same spot, and many of the mothers just happened to be accompanied by young, but they were not necessarily living in organized herds.

Remains of other species found at Tanque Loma include Glossotherium (a smaller probably hairier species of ground sloth), pampathere (a giant armadillo), an extinct species of horse, and a deer related to the modern day whitetail.

Note to paleoecologists:  Nobody has yet studied the plant species composition of the sloth feces and gut contents found here.

Reference:

Lindsey, E.; et. al.

“A Monodominant Late-Pleistocene Megafauna Locality from Santa Elena, Ecuador: Insight on the Biology and Behavior of Giant Ground Sloths”

Paleogeography, Paleoclimatology, and Paleoecology 544 April 15, 2020

https://www.researchgate.net/publication/338565424_A_monodominant_late-Pleistocene_megafauna_locality_from_Santa_Elena_Ecuador_Insight_on_the_biology_and_behavior_of_giant_ground_sloths