Archive for the ‘Pleistocene Mammals’ Category

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.

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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

A Shocking New Study of Dire Wolf (Canis dirus) DNA

January 15, 2021

Dire wolves were one of the most common large predators of Late Pleistocene North America, and sub-fossils of this species are common, but scientists have had difficulty finding specimens with enough intact DNA to analyze.  There are thousands of dire wolf fossils excavated from the La Brea Tar Pits in California, but this DNA is contaminated with tar and can’t be used.  There are also many specimens of dire wolf fossils from Florida, but the humidity there causes DNA to deteriorate and become unusable.  However, Angela Perri, a zooarchaeologist from Durham University, made a concerted effort to find dire wolf specimens with enough viable DNA to study, and she found 5 specimens.  Labs from Australia and England analyzed the DNA from these specimens and came to a stunning conclusion–dire wolves were not closely related to gray wolves (Canis lupus) as most paleontologists had assumed, and they were not really even wolves.  Instead, they were the last in a lineage of now extinct ancient canids.

Dire Wolves Were Not Really Wolves, New Genetic Clues Reveal

Illustration by Mauricio Anton of dire wolves interacting with timber wolves. Dire wolves were larger and may have had shorter reddish coats.


The genetic study determined the ancestor of dire wolves diverged from the ancestor of gray wolves at least 5.7 million years ago.  The closest living relative of the dire wolf is the African jackal (C. mesomelas), but the ancestor of that species diverged from dire wolf ancestors about 5.1 million years ago.  Interestingly, jackals can interbreed with wolves, but the study of dire wolf DNA found no evidence of interbreeding between gray wolves and dire wolves.  Apparently, the 2 species had been geographically isolated from each other for too long, and when they came into contact did not recognize the other as possible sex partners.  This study casts doubt on my hypothesis that an extinct ecomorph of Beringian gray wolves were a gray wolf/dire wolf hybrid.  (See: https://markgelbart.wordpress.com/2016/05/30/beringian-wolves-an-extinct-ecomorph-of-canis-lupus-lived-as-far-south-as-wyoming/ )
Paleontologists assumed dire wolves were close relatives of gray wolves because their anatomy was so similar.  Dire wolves had broader skulls, bigger teeth, shorter limbs, and were more robust; but otherwise they were much alike.  The similarity can now be attributed to convergent evolution when unrelated species evolve similar traits in response to similar environmental conditions.

Canids originated in North America, but the ancestors of gray wolves, coyotes, and jackals colonized Eurasia and Africa and evolved separately from dire wolves whose ancestors remained in North and South America.  (Dire wolves ranged from Alberta south to Peru and from California east to the Atlantic Coast.)  Dire wolves appear suddenly in the fossil record 200,000 years ago.  Most paleontologists think they evolved from Armbruster’s wolf (C. arbrustrei). No scientist has considered the possibility, but maybe this line evolved from the bone-eating dogs (Borophagus), a group of canids that seemingly disappeared early during the Pleistocene.  Scientists can’t investigate this because no viable DNA from Borophagus dogs remains viable. Dire wolves were adapted to live in climates ranging from temperate to sub-tropical.  Scientists weren’t able to sequence the entire genome of the dire wolf to determine its appearance, but they may have had shorter more reddish coats than gray wolves and probably preferred warmer climates.  The ancestor of gray wolves and coyotes crossed the Bering Land Bridge and colonized North America at least 20,000 years ago and overlapped with dire wolves for about 10,000 years.  Gray wolves co-evolved with humans and learned to fear man.  Dire wolves never learned to fear man, and likely could not compete with humans.  I think this explains their extinction, while wolves and particularly coyotes continue to hang-on.  

The authors of the new study think dire wolves are so different from gray wolves they should be given a separate genus name–Aenocyon.  One of the first paleontologists who looked at dire wolf bones assigned this genus name to dire wolves, but it fell from fashion because of the misconception that dire wolves were close kin to gray wolves.  Turns out he was right; later paleontologists were wrong.

Reference:

Perri, A.; K. Mitchell, L, Frantz; et. al.
“Dire Wolves were the Last of an Ancient New World Canid Lineage”
Nature 2021




Cave Paintings of Megafauna in the Amazon Rain Forest

December 5, 2020

Archaeologists have been studying ancient paintings on cave and rock shelter walls in Cheribiquete National Park for over 30 years, but last year they discovered an 8 mile stretch that includes rare images of extinct megafauna.  Cheribiquete National Park is located in Colombia and covers 17,000 square miles–the largest tropical forest park in the world.  The newly discovered rock shelter walls are illustrated with images of a giant ground sloth and young, horse, llama, macrauchenia, gompothere, and perhaps bear.  An extinct species of horse known as hippidion lived in South America over 10,000 years ago.  The llama depicted on the wall maybe an extinct or extant species.  All the images are crudely drawn and don’t depict adequate details to distinguish species identification.  These may be the only images of a gompothere and macrauchenia that have ever been drawn by people who actually saw them alive.  Gompotheres were a mastodon-like animal, similar to elephants, but nothing like a macrauchenia lives today.  Their closest living relatives are rhinos, horses, and tapirs; but genetic evidence suggests they diverged from those odd toed ungulates 66 million years ago when dinosaurs became extinct.  Macrauchenia were adaptable animals capable of living in many different kinds of habitats, and they likely occupied a giraffe-like ecological niche because they had long necks.  Fossil remains of macrauchenia are not found anywhere near Cheribiquete National Park, showing how inadequate the fossil record is.

Image

Rock art paintings of pre-historic megafauna.  The art work is poor, but I think they depict a ground sloth and young, gompothere (an animal similar to a mastodon), a llama, an horse, and a bear or another ground sloth?, and a macrauchenia.  It looks like a man is hunting the gompothere (a juvenile?) with a club or atlatl.  It also looks like a man has his armed raised at the ground sloth, but the atlatl isn’t drawn.  In another image it looks like the man is stabbing the bear in the side.

Colombia expands Chiribiquete National Park

The Natives must have used ladders to paint these figures on some of the rock shelters.  They are much higher than a human can reach.  Archaeologists used drones to photograph some of them.

Archaeologists suggest the natives scaled the high rock shelter walls to paint these images.  I think it is more likely they used ladders to reach these heights.  The paintings are thought to vary in age from about 15,000 years BP to the 16th century.  Apparently, natives stopped painting walls shortly after European contact perhaps because the culture shock of this interaction destroyed American civilizations.  The paintings themselves can’t be radio-carbon dated because the substance used was inorganic.  European cave paintings were drawn with charcoal and can be radio-carbon dated.

Some of the articles reporting this discovery are written by people who assume the presence of the animals depicted on the rock shelter walls is evidence of a different local environment during the Late Pleistocene than occurs there today.  This is not necessarily true.  Macrauchenia was a generalist species, and gompotheres likely preferred dense forests.  Clearings in the forest created by gompothere foraging may have sustained populations of horses and llamas.

In addition to the extensive rock shelter drawings, Cheribiquete National Park is home to 82 species of mammals (52 of them bats), an astonishing 410 species of birds, 60 species of reptiles, 57 species of amphibians, 238 species of fish, and over 200 species of butterflies.  Notable animals include jaguars, cougars, monkeys, armadillos, peccaries, tapirs, scarlet macaws, emerald hummingbirds, and harpy eagles.  The park has great potential as a tourist destination.  Unfortunately, it is also an hideout for thousands of FARC rebels.  FARC is an organization that basically is a bunch of communist gangsters who kidnap people for ransom and sell cocaine.  FARC battled the Colombian government for 40 years before finally signing a peace agreement recently, but the region is still not safe enough for tourism.

Mastodon Ranges Fluctuated with Climate Changes

November 21, 2020

When I first began my blog I was unsure of my writing, so I submitted samples to an internet forum at absolutewrite.com.  One person criticized me for being redundant when I wrote about mammoths and mastodons because he wrongly assumed I was referring to the same animal.  I explained they were 2 completely different species: mastodons were a semi-aquatic animal that mostly ate leaves, twigs, and fruit; while mammoths were an upland species that mostly ate grass.  The lead author of a new study of mastodon genetics admitted he had the same misconception prior to studying the mastodon genome.  Emil Karpinski is a geneticist not a paleontologist, and his false assumption is understandable. Karpinski and his colleagues sequenced the complete genomes of 33 individual mastodon specimens and the partial genomes from an additional 12 individual specimens.  They found 5 major clades from different geographical locations including Alaska, Yukon, Alberta/Missouri, Mexico, and Virginia/Great Lakes.  A single specimen from Nova Scotia indicates the possible discovery of a 6th clade.  Genomes of mastodons from Alberta suggest a mixture of 3 different clades.  This region was a migratory corridor between the Cordilleran and Laurentide Glaciers during interglacial climate phases when Ice Sheets retreated.  Different populations came into contact here when mastodons expanded their range north during interglacials.

Image showing how mastodon ranges expanded during interglacials and contracted during Ice Ages.  Southern mastodons were more genetically diverse than northern mastodons because northern populations were extirpated during every Ice Age.  From the below reference.

Map showing location of mastodon specimens used in the genetic study.  Also from the below reference.

The genetic evidence clearly shows mastodons expanded their range into Canada and Alaska between Ice Ages, and the expansions occurred at least twice, probably more.  Spruce forests and wetlands in Alaska converted into dry grassland during Ice Ages–unsuitable habitat for a semi-aquatic species.  And of course Canada was covered with thick glacial ice–inhospitable to most life.

The authors of this paper express bafflement over why mastodons did not recolonize Alaska and Canada following the last Ice Age.  Wetlands and spruce forests expanded when glaciers retreated and left behind meltwater lakes and bogs.  The answer is obvious and no mystery at all.  Men disrupted mastodon migration routes and overhunted them to extinction.  Large areas of suitable mastodon habitat exist today all over North America, but they are devoid of these massive beasts because they could not co-exist with increasing human populations.

Reference:

Karpinski, E.; et. al.

“American Mastodon Mitochondrial Genomes Suggest Multiple Dispersal Events in Response to Pleistocene Climate Oscillations”

Nature Communications 11 Article 4048 (2020) 

https://www.nature.com/articles/s41467-020-17893-z

 

Pleistocene Bush Dogs (Speothos sp.)

November 7, 2020

Scientists occasionally discover species as fossils before they are known to still be extant. The coelacanth and the Chacoan peccary are famous examples of this. Add South American bush dogs (Speothos venaticus) to the list.  A Danish paleontologist discovered bush dog bones in a Brazilian cave during 1839 and mistakenly thought he’d found evidence of an extinct species.  However, bush dogs still exist, though I can’t determine which western scientist first realized they were not extinct.  I’m sure native Americans were aware of their existence and may have kept some of them as pets once in a while.

Bush dogs range throughout the tropics from Brazil to Costa Rica.  Science was unaware of their existence in Costa Rica until last year, and they are not included in a book I covered on my blog recently–Mammals of Costa Rica by Mark Wainright.  Bush dogs are most common in Suriname and Guyana.  They prefer lowland tropical forest, wet savannahs, brush, and pasture habitats.  They reach a length of 2 feet long and weigh up to 18 pounds.  Bush dogs hunt in packs during the day, and their favorite prey are large rodents including pacas, agoutis, and capybaras.  The former 2 are uncommon in populated areas where natives hunt them for food, and this explains why bush dogs are also uncommon.  Competition with man has likely reduced bush dog numbers over the past 14,000 years.  Bush dogs have also been reported attacking peccaries, deer, armadillos, and rheas.

Bush dogs (Speothos venaticus) are an elusive (and very cute) species of  pupper native to tropical South America! : rarepuppers

Bush dogs. They may be similar to many species of extinct primitive canids.

File:Speothos venaticus range map.png - Wikimedia Commons

Bush dog range map.  This map doesn’t include documented sightings with photos taken in Costa Rica last year.

Canids first evolved in North America and were more diverse during the Miocene over 5 million years ago.  Cats from Eurasia then invaded the Americas and caused the extinction of many dog genera by outcompeting them.  A genetic study determined bush dogs are a sister clade with African hunting dogs (Lycaon pictus).  A species of hunting dog occurred in North America during the mid-Pleistocene.  Fossils of this species were found in Texas, and it is known as Troxell’s dog (Protocyon texanus).  Troxell’s dog also had short legs and dentition that resembled that of bush dogs.  This genetic study determined the ancestor of bush dogs diverged from the ancestor of African hunting dogs about 7.5 million years ago.  Amazingly, the bush dog’s closest relative lives on the other side of the planet.  Another genetic study found bush dogs are more closely related to wolves than they are to raccoon dogs or foxes.  However, they are not closely related enough to mate with wolves or domestic dogs and produce fertile offspring.

During the Pleistocene extant bush dogs co-occurred with another species of now extinct bush dog (S. pacivorus).  The latter species was slightly larger.  More carrion from extinct megafauna supported greater populations of predators then.

Spotted Hyenas (Crocuta crocuta) May Have Persisted in Europe until 7,000 BP

October 3, 2020

European climate might be more suitable for spotted hyenas than African climate, according to a 10 year old study published in Quaternary Science Review. Ironically, the spotted hyena is presently extinct in Europe and survives on the continent of Africa and nowhere else, except zoos. Hyenas thrived from Spain to the Ural Mountains for about 3 million years. Genetic evidence suggests hyenas from Africa invaded Europe in 3 waves: 3 million years ago, 1 million years ago, and again 300,000 years ago. The hyenas in Europe were a subspecies of the African hyena, given the scientific name Crocota crocota spelaea and are commonly known as the cave hyena, though most individuals never ventured into a cave. Their primary prey consisted of horse and bison, but their diet also included rhino, deer, ibex, bear, lion, wolf, and other hyenas. Some of these prey items were scavenged, but hyenas actively kill most of their food. European hyenas were on average 40% larger than African hyenas–evidence European climate and habitats were a more optimum environment for them. European female hyenas (for hyenas females are generally larger than males) weighed up to 225 pounds, while African hyenas weigh up to 140 pounds. Hyenas occurred in Europe during all climate phases of the Pleistocene, including interglacials, glacials, interstadials (warms ups during cold stages) and stadials (cool downs during warm stages). This suggests climate change alone can not explain their extinction in Europe. Competition with humans was likely the cause of their extinction there, though scientists believe hyenas succumbed to a combination of environmental change and competition with humans. I disagree with this notion because if humans are eliminated as a variable in the equation, hyenas would still occur in Europe. Thus, humans alone are the cause of their extinction. Hyenas persist in Africa because tropical diseases kept human populations low on large areas of that continent.

Cave hyena (Crocuta crocuta spelaea)

Image of Crocuta crocuta spelaea.

Fossil Presence of spotted hyenas in Europe from 126,000 years BP-21,000 years BP. Note how they still occurred in the middle of Europe during the Last Glacial Maximum (the white circles). Image from the below reference authored by Vareles et. al.

Scientists think hyenas went extinct in Europe about 11,000 years ago, but a new study touts evidence hyenas persisted in Spain until ~7,000 years ago. Some Spanish scientists studied hyena coprolites (fossil feces) found in 2 caves in Spain. The coprolites dated between 37,000 calendar years BP-7,000 calendar years BP. The authors of this study concede younger dated coprolites might have inaccurate dates due to contamination. However, the focus of their study was an analysis of pollen grains found in the hyena coprolites. Palynologists attempt to reconstruct past environments based on the composition of pollen grains, and they use them to estimate past climate. For example during cold dry climate phases pine and grass pollen predominates in samples, while moist warm climate phases show an increase in oak pollen. The pollen profile of the youngest dated coprolites are consistent with the floral composition of the early Holocene, so it seems likely the radio-carbon dates are accurate, and hyenas lived in Spain as recently as 7,000 years ago.

References:

Deidrich, L; and K. Zak

“Prey Deposits and Den Sites of the Upper Pleistocene Hyena Crocuta crocuta spelaea (Goldfuss 1923) in Hoorjostid and Ventral Caves of the Bohemian Karst (Czech Republic)”

Bulletin of Geoscience 84 (4) 2006

Ochard, J. et al

“Palynology and Chronology of Hyena Coprolites from the Pinur Karstic Caves Las Ventanas and Carihoula, Southern Spain”

Paleogeography, Paleoclimatalogy, and Paleoecology 552 August 2020

Vareles, S; J. Lobo, J. Rodriguez, and P. Baten

“Were the Late Pleistocene Climate Changes the Responsible for the Disappearance of the European Spotted Hyena Population? Hindcasting a Species Geographic Distribution over Time”

Quaternary Science Review 29 2010