Archive for the ‘Pleistocene Mammals’ Category

Goodbye Right Molar #2, Hello Legal Pot Dispensaries in Georgia

September 22, 2022

The dentist and the dental hygienist were shocked my right molar didn’t hurt when I went for my first teeth cleaning in 10 years. It used to hurt. In 1998 my old dentist filled a large cavity and told me he didn’t think the filling would last 6 months, and I would eventually require a root canal. I’d heard nothing but bad things about root canals, and I began flossing regularly. The tooth endured with no change for 20 years, though it occasionally ached. One evening, I was watching The Walking Dead television show, while snacking on corn chips. I started digging what I mistakenly thought were chewed up corn chips stuck in my right molar, and I pulled out most of that dental work. My right molar never hurt again. By odd coincidence, I later learned my old dentist died suddenly in his office that same week. My new dentist took one look at this molar and said extraction was the only option–not even root canal could save it. I scheduled an appointment to have it removed, but 10 days before this date, it became loose and fell out when I flossed. If I didn’t already have an appointment, I’d leave that spot alone, but the dentist will still want to remove the roots to prevent infection. This procedure shouldn’t be a big deal. He’ll numb the area and use forceps to wiggle the roots free.

I want to keep the rest of my teeth and that means regular visits to the dentist. Like a kid, I need an incentive. Kids get candy for being good, so I’m going to give myself adult candy and visit a local cbd smoke shop every time I have a dental appointment. Stores that sell cannabis products are now offering Delta-8 cbd. Illegal marijuana is Delta-9, but chemists use isomerization to change Delta-9 to Delta-8. Delta-8 has the exact same chemical composition as Delta-9, but it has a different structure, so technically it is legal. I wasn’t impressed the first time I tried Delta-8–the high was mild and short-lived. However, smoke shops and convenience stores that sell Delta-8 are not regulated at all, and I believe some of the Delta-8 products they sell have considerable amounts of residual Delta-9. Last time I tried it, I could not tell the difference. The FDA warns there have been hundreds of people who have gone to emergency rooms across the country after consuming Delta-8, but this is out of tens of millions of users. Those people were probably not used to getting high or simply suffered unwarranted paranoia–a side effect of marijuana consumption. I don’t think state authorities are eager to crack down on cbd shops. I think they don’t want people from Georgia traveling to other states to purchase recreational pot because it means lost tax revenue. So pot is basically legal here now.

Honest, I wasn’t high when this thought occurred to me. What if the human race became extinct, and the only evidence left of our existence was my broken tooth pictured above? How would alien paleontologists exploring our planet imagine what we looked like based on 1 broken tooth? The only evidence of the existence of an extinct ape known as Gigantopithecus blacki is about 60 teeth–no other skeletal remains have been found. This species is thought to have lived from 2 million years BP-300,000 years BP. They lived in jungle environments with acid soils where fossil preservation is rare. Their teeth were found in caves with the remains of stegodon, rhino, tapir, goat, deer, ancestral tiger, hyena, dhole, and bear. Scientists believe they ate forest plants, especially fruit. 15 of the 62 teeth found so far have tooth decay. This species could have used a dentist. Scientists think its closest living relative was the orangutan, but it is believed to have been much larger. In my opinion artists’ depictions are quite fanciful, based on wild guessing.

Paleontologists imagine Gigantopithicus looked like this. The only fossil evidence of this species is some 60 odd teeth. I think this reconstruction is a stretch.

Pleistocene Paw, Hoof, and Footprints in New Mexico (redux)

August 17, 2022

I already wrote an article with this title 2 years ago, but a minor disaster last week inspired me to rewrite it. In the original article I wrote the fossilized human footprints found at White Sands National Park were at least 11,000 years old. A new study published last year determined the footprints were between 23,000 years-21,000 years old. I tried to edit in a note to the old article explaining the results of the new study, and some kind of glitch erased the last 2 paragraphs and the image I used for the original article. I could look for the old handwritten first draft in a stack of old notebooks I keep in a dusty, old, cardboard box, then retype it, but I decided to start all over and rewrite it completely.

During the late Pleistocene climate patterns were much different in the American Southwest than they are today. The region enjoyed higher rainfall and a cooler more temperate climate, resulting in abundant lakes. Lake Otero, now a completely dry lakebed, was filled with water then and surrounded with lush prairie and scattered trees. A drier climate phase struck, and the lake began to recede, leaving a muddy shoreline where many species of mammals left trackways, including humans, mammoths, camels, bison, Harlan’s ground sloths, saber-toothed cats, giant lions, and dire wolves. Some of the human trackways crisscross those of a ground sloth, and it appears as if the sloth paused and stood, so the animal could better detect the human scent. 61 fossilized human footprints have been found here, and they are mostly of teenagers and children. Apparently, the teenagers were going back and forth, as if they were carrying objects. Children appear to be playing. Scientists hypothesize the adults were fishing and/or collecting edible aquatic plants, and the teens were carrying the items to a camp (not yet found by archaeologists). One teenager was babysitting a toddler and carrying it around.

Human trackways at White Sands National Park in New Mexico. Some scientists estimate these footprints are about 21,000 years old. Human trackways are interspersed with the prints of Pleistocene megafauna.
Artist’s rendition of White Sands National Park 21,000 years ago. Image is a courtesy of the National Park Service.

Of course, fossilized footprints can’t be radiocarbon dated, so how did scientists date the trackways? They radiocarbon dated the ditch grass (Ruppia cirrhosa) seeds found in sediment above and below where the trackways are located. They determined the trackways are between 23,000 years BP-21,000 years BP. This evidence contradicts mainstream archaeologists who believe humans didn’t arrive in North America until about 14,000 years ago.

Diagram showing how the conclusions by the above discussed study could be wrong. Gary Haynes believes wind erosion redeposited older sediment over younger sediment or simply displaced younger sediment so 21,000-year-old ditch grass seeds were on the surface when men and megafauna walked in the area 13,000 years ago. Image from the below reference (Haynes 2022).

Gary Haynes, a renowned archaeologist, casts doubt on the purported age of the trackways. In an article he published in the journal PaleoAmerica, he points out 3 factors that could cause the scientists to reach misleading conclusions about the age of the trackways. The presence of hardwater in an environment causes radiocarbon dates to be older than they actually are. The scientists who dated the trackways were aware of this but think this isn’t a problem because local water is currently not hard. However, Haynes points out they didn’t analyze modern ditch grass to see if it absorbs a greater concentration of hard water than is found in the environment. Another factor that could cause misleading dates is redeposition of sandy sediment by wind. One study of a stratigraphic column in the area nearby found roughly half of the dates were out of order with older sediment on top of younger sediment and alternating with it. Haynes thinks the stratigraphic column in the region where the trackways are found date to between 15,000 years BP-11,000 years BP, dates consistent with when the Clovis culture was known to occur in North America. Finally, he thinks the trackways were made 13,000 years ago, but the exposed sediment where the humans and animals walked happened to be older due to wind redeposition. In other words wind blew the younger sediment away, and people and animals were walking on old sediment.

M. Bennett is the lead author of the study determining the trackways were 21,000 years old. His response to Haynes’s alternative explanation was short and rather obtuse. He believes it was unlikely redeposition of windblown sand occurred, but he offers no explanation why. He also stated the trackways couldn’t be of Holocene age because the human trackways were interspersed with Pleistocene megafauna trackways, and Pleistocene megafauna were extinct by the Holocene (beginning about 11,000 years ago). However, Haynes merely quoted another study that mentioned the trackways being of Holocene age was just 1 of 3 possibilities. Bennett didn’t even address Haynes’s belief that the trackways date to 13,000 years BP when Pleistocene megafauna still roamed the region.

References:

Bennett, M. , et. al.

“Evidence of Humans in North America during the Last Glacial Maximum”

Science 373 6562 2021

Haynes, G.

“Evidence for Humans at White Sands National Park during the Last Glacial Maximum could be for Clovis People ~13,000 years ago”

PaloeAmerica March 2022

Aborigines may have Occurred in South America and Southwestern North America Before the Last Glacial Maximum

August 10, 2022

There is tantalizing genetic and archaeological evidence suggesting small ephemeral populations of people related to Australian aborigines occupied parts of South America and southwestern North America thousands of years before Amerindians colonized the continents. The archaeological evidence predates or at some sites is simultaneous with the Last Glacial Maximum, the climate phase when the most recent Ice Age glaciers reached their greatest extent about 21,000 years ago. Mainstream archaeologists long believed the first humans arrived in the Americas about 14,000 years ago, but there are just too many compelling archaeological sites, especially in South America and southwestern North America, that contradict this view. The radio-carbon dates can’t be wrong on all of them. Examples of archaeological sites predating or simultaneous with the Last Glacial Maximum include Monte Verde, Chile (33,000 years BP), Toca de Tara Peia, Brazil (20,000 years BP), Arroyo del Vizcaina, Uruguay (30,000 years BP), fossil footprints in Argentina (30,000 years BP), Chiquihuite Cave, Mexico (26,000 years-19,000 years BP), Conxcatlan Cave, Mexico (30,000 years BP) and fossil footprints in New Mexico (21,000 years BP). Now, a recent study of a site in New Mexico determined humans butchered a mammoth and calf here 37,000 years ago.

The recently studied site located in New Mexico is known as the Harley Mammoth Locality named after the hiker who found it. Scientists examined the mammoth bones using CAT scans and determined the mammoths were butchered by humans. The skulls were broken to extract the calorie-rich brains. Ribs were removed from vertebrae–a logical step when breaking down a large mammal. Calorie-rich marrow was extracted from the bones as well. 6 chert flakes, debitage from toolmaking, were found in situ. And it appears as if some of the bones were used for fuel to cook fish over open campfires. Fish scales were found, though the site is 70 yards from the nearest source of water. There is no sign of carnivore scavenging, but the scientists did find termite and cicada burrows in the bones. Insects likely burrowed into the bones after they were slowly buried when rain over time washed sediment downslope over the bones. Later, wind eroded some of this sediment away, allowing Hartley to find some of this material.

Stones modified by tool-making found at the Hartley Mammoth Site dated to an incredible 37,000 years BP. Image from the below reference.
Mammoth bones with evidence of human butchering. From the Hartley Mammoth Site located in New Mexico. Image also from the below reference.

3 Indian tribes found in the Amazon Basin, including the Surui, Karitiana, and Xavanti, have a genetic marker suggesting some of their ancestry is related to the ancestors of Australian aborigines. This genetic marker is known as the Y population and is found in no other known populations of Indian tribes. The oldest known human skeleton in the Americas, the Anzick child from South Dakota, dates to about 12,900 years ago and does not have this genetic marker. This genetic evidence suggests 2 different populations colonized the Americas. Aborigines colonized Australia about 40,000 years ago, and it seems likely they were capable of long-distance sea travel then–a knowledge that was lost over time. Small groups of them may have discovered South America at about the same time their relatives found Australia. Maybe, they were so traumatized by harrowing sea journeys, they decided to stick to land, and over a generation they forgot how to travel by sea. I hypothesize populations of aborigines in America remained low over millennia and likely were always on the verge of extinction in the harsh environments of the Late Pleistocene. The later invasion of more technologically advanced Indians probably displaced the aborigines across most of their range with the exception of the Amazon Basin where they interbred. Perhaps, Indians were more dependent upon aborigine knowledge in the more challenging environment of the Amazon jungle.

3 tribes in the Amazon basin have a genetic signature shared with Australian aborigines. No other Indian tribes in the Americas have this signature. These tribes may be relics from a more widespread population that was displaced by Indians during the Late Pleistocene. Linguistic evidence also suggests the former existence of aborigines alongside Amerindians.

Apparently, aborigines didn’t have as negative an impact on megafauna populations as the Indians. They were fewer in number and never specialized in hunting megafauna, though they did occasionally kill large animals. They probably preferred exploiting small game and fish because it was less risky. Small aborigine tribes couldn’t risk casualties when hunting larger more dangerous animals.

Reference:

Rowe, T. et. al.

“Human Occupation of the North American Colorado Plateau ~37,000 years ago”

Frontiers of Ecology and Evolution July 2022

https://www.frontiersin.org/articles/10.3389/fevo.2022.903795/full#S12

They Yturria Ranch in Southeast Texas

July 6, 2022

Some of the best places to see wild megafauna are areas managed by humans. The Yturria Ranch, located in southeast Texas, is a good example of a wildlife haven enhanced by people. During 1849 Francisco Yturria inherited his wife’s land grant and became the owner of 312 square miles. He made a smart decision shortly after the Mexican War and sided with local white people (the winning side) in their dispute with Hispanic partisans who wanted to take land back for Mexicans. This cemented his claim on the land. Today, Richard Butler, a 5th generation descendent of Yturria, owns the ranch, though it has been whittled down to 22 square miles. Still, it is so big it has its own railroad stop. It has always been a working cattle ranch, but now much of the ranch’s revenue comes from offering hunters the chance to shoot exotic big game. The land here has been improved by wildlife managers to help support native species and the introduced populations of African and Indian antelopes that make the ranch an impressive refuge for megafauna.

Tractors are used to disc the land, a process that disturbs the soil and increases the variety of plant species able to thrive, thus providing a wide range of food for animals. Wells and manmade water tanks attract thirsty wildlife. And ranch managers are working to restore native Tamaulipas thorn scrub, a type of environment with dry soils high in calcium. Mesquite, plateau live oak, cenizo, acacia, Texas ebony, Texas persimmon, yucca, and a variety of unusual forbs and grasses grow on Tamaulipas thorn scrub land. Other environments found on the ranch include coastal savannah, live oak forests, mesquite groves, pastures, and wetlands.

The ranch is rich in native and nonnative megafauna populations. In addition to white tail deer and collared peccary, hunters seek out African waterbuck, oryx, and lechwe or Indian blackbuck and nilgai antelope. Feral hogs must also be abundant, though not advertised (hunters can kill them just about anywhere). Zebras roam the ranch too. Predators living on the ranch include coyote, cougar, bobcat, and ocelot. Ranch managers participate in ocelot conservation. This species is uncommon on this side of the Rio Grande. The ranch hosts more species of megafauna today than have been found here since the late Pleistocene, at least 12,000 years ago. The ranch supports healthy populations of turkey and quail. Caracaras, roadrunners, and species of birds that prefer scarce human populations nest on the ranch.

The Yturria Ranch is a vast wilderness.
Herd of endangered oryx antelope on the Yturria Ranch.
Blackbuck antelope, native to India, abound on the Yturria Ranch.

It costs $1500 a night to stay on the ranch, and there is a 2-day minimum. Hunters with the urge to kill exotic animals are probably the most frequent guests, but one doesn’t have to be a hunter to stay here. Guided fishing trips and bird tours led by professional ornithologists are offered. I’d be happy just to take a walk and photograph any wildlife I encountered. I briefly fantasized about living in the area. The ranch spans parts of 2 counties, but from a satellite view it looks like there is just 1 suburban residential development in the area, and shopping centers are scarce. However, San Antonio looks to be about an hour away, and Padre Island beach is about 30 minutes away. New Orleans is a day’s drive. Climate is subtropical and grapefruit are grown nearby. I wonder if beef prices are cheaper here because it is close to the source. I think this region is a pretty nice choice for retirees.

Mauricio Anton’s New Reconstruction of the Scimitar-toothed Cat’s (Homotherium latidens) Face

June 29, 2022

Most people don’t know there were 2 species of fanged cats living in North America during the Pleistocene. Smilodon fatalis is the more famous species because fossil specimens of this extinct animal are relatively abundant, especially from the La Brea Tar Pits fossil site in California. But there was a lesser-known species that was more widespread, ranging from Africa across Eurasia to Florida. This species is often referred to as the scimitar-toothed cat. In Africa and Eurasia it is given the scientific name Homotherium latidens, and in North America it’s given the scientific name H. serum, but genetic evidence suggests they could be considered the same species. Despite a widespread geographic distribution, the genetic evidence also suggests the scimitar-toothed cat existed in low population numbers. It is uncommon in the fossil record, and in Europe there is a large gap in occurrence. Fossil evidence of H. latidens is known from a 300,000-year-old fossil site but is not recorded again in Europe until a specimen was found dating to 28,000 years ago in the North Sea which was above sea level at that time. Although it was never a common animal, the scimitar-toothed cat was a long-lived species, originally evolving during the late Pliocene and not becoming extinct until the late Pleistocene–a time span of over 2 million years. Evidence from the Friesenhahn Cave site in Texas indicates it may have specialized in hunting juvenile mammoths and mastodons in North America. Some think it must have hunted in packs, but it may have had a technique that made individuals capable of bringing down much larger prey. They had unusual sloping backs, much like modern spotted hyenas.

Mauricio Anton is a talented paleo artist who beautifully illustrated the excellent book The Big Cats and their fossil relatives. He works with paleontologists to produce anatomically accurate drawings of extinct species of cats and other animals. His original drawing of the scimitar-toothed cat depicted the fangs protruding when it mouth was closed. However, in a recent study involving 3 scientists, he determined the fangs on this species did not protrude when its mouth was shut.

Images of scimitar-toothed cat and a tiger skull and jaw.
Maricio Anton’s new reconstruction of a scimitar-toothed cat’s face. He now believes its fangs didn’t protrude when its mouth was closed. However, he does think the saber-toothed cat (Smilodon fatalis) did have protruding fangs when its mouth was closed.

For this study Anton and his colleagues looked at cat scans of extant big cat skulls and jaws and watched videos of them yawning and opening and closing their jaws. They also re-examined the skulls and jaws of Homotherium specimens. They concluded the fangs were not exposed when the scimitar-toothed cat closed its mouth. They still think the more famous species of saber-toothed cat (Smilodon fatalis) did have exposed fangs when its mouth was closed. The fangs on the latter species were much longer. Other species of pre-historic cats and cat-like species may or may not have had exposed fangs when their jaws were shut, depending upon the characteristics of each individual species.

Note on the reference: In the paper below they refer to the scimitar-toothed cat as the saber-tooth cat for its common name. I prefer to call it the scimitar-toothed cat to prevent confusion with its more famous relative.

Reference:

Anton, M.; G. Siliceo, J. Pastor, and M. Salesa

“Concealed Weapons: A Revised Reconstruction of the Facial Anatomy and Life Appearance of the Sabre-toothed Cat Homotherium latidens (Felidae, Machairodontinae)”

Quaternary Science Review 284 2022

New Study Supports Human Overkill as cause of Megafauna Extinctions in the Middle East

June 22, 2022

The Middle East is a gateway between African and Eurasian faunas. Elephants, humans, and big cats among other animals originally evolved in Africa and spread through the Middle East to Eurasia and beyond. The Middle East, also known as the Levant, encompasses Israel, the Sinai Peninsula, Jordan, Lebanon, and Syria. Humans and their evolutionary ancestors beginning with Homo erectus have had a continuous presence in the region for at least 1.5 million years, and it is a good place to study the historical interaction between human species and Pleistocene megafauna. A recent survey of data from 58 archaeological sites in the Levant concluded the average size of the animals humans hunted declined over time throughout the past 1.5 millions years. The study also compared this data with temperature changes and changes in paleoenvironmental conditions and found little correlation between these factors and the decline in average animal body size. Therefore, they determined human hunters were entirely responsible for the disappearance and/or decline of megafauna populations from this region.

Map of the sites surveyed in the below referenced study.
Graph showing the decline in megafauna body size over the past 1.5 million years from archaeological sites located in the Middle East. From the below referenced study. The authors attribute this to human hunting, not changes in climate or paleoenvironmental conditions.

Africa did not experience many extinctions during the late Pleistocene as other parts of the world did when humans colonized new territory. However, there was a spike in extinctions of large mammals in Africa during the beginning of the Pleistocene. One example is an extinct species of giant baboon (Therepithecus oswaldi), an animal that occupied a similar niche as Homo erectus. There is direct evidence of Homo erectus killing 90 giant baboons at a site in Kenya, and I have no doubt they are responsible for the extinction of this species. Some scientists believe some species of megafauna were able to persist in Africa because the animals there co-evolved with man and had time to learn better survival strategies than megafauna in other parts of the world. Although this may be partly true, I think African megafauna survived to the present because large parts of the continent were frequently depopulated and uninhabited by man due to tropical diseases and intertribal warfare. Megafauna consistently found refuge in the depopulated areas.

Megafauna was able survive in the Levant until quite late in the Pleistocene, but the average size of the 83 species found at the 58 archaeological sites declined over time, and some of the larger species did eventually disappear. Elephants became extirpated in the Levant 125,000 years ago, hippos vanished here 42,000 years ago, rhinos met their demise 15,500 years ago, and the final population of the aurochs (ancestor of the domestic cow) was wiped out in the region 3500 years ago. The authors of this study believe humans preferred hunting larger animals because they provided more meat, and it took less skill to hunt them. A group of men with spears could easily bring down any large beast. Paradoxically, human hunting technology advanced when megafauna became scarce, and humans were forced to hunt smaller more elusive prey.

Reference:

Dembitzer, J. R. Borkei, M. Ben-dor, and S. Neiri

“Levantine Overkill: 1.5 million Years of Hunting Down the Body Size Distribution:

Quaternary Science Review 276 2022

Pigloos

March 30, 2022

Wild boars (Sus scrofa) are an amazing adaptable Pleistocene survivor. Their fierce disposition and large litter sizes enabled them to survive predation from wolves, lions, and humans during the Pleistocene, and even today modern human hunters, sometimes armed with machine guns, have trouble putting a dent in their populations. They eat just about anything, and they can live in most climates. Wild boar remains, dating to the Pleistocene, have been found in at least 109 fossil sites located in Israel, Morocco, Libya, Greece, Monaco, Italy, France, Spain, Portugal, Germany, Austria, the United Kingdom, Slovakia, the Czeck Republic, Russia, China, Vietnam, and Indonesia. Some populations of wild boar were domesticated 5,000 years ago, and their descendants are modern day pigs–source of the pork chops, ribs, and bacon stocked by supermarkets. European settlers brought pigs to the Americas 500 years ago and let them forage in the woods where many escaped and went wild. 100 years ago, hunters introduced wild boars to the Appalachians, and they promptly interbred with existing wild pig populations, creating a kind of super hog that game managers have difficulty controlling. Pure bred wild boars wouldn’t be unmanageable, but domesticated pigs have been bred to produce exceptionally large litters, and the combination of tough wild boar with pigs that produce super-sized litters has overwhelmed many areas.

Wild boars have been abundant for over a million years.

Hunters recently introduced wild boars to Canada, resulting in the same situation found in parts of the U.S. and South America. Their ability to adapt to frigid Canadian climates surprised researchers. During winter these intelligent animals build houses constructed of cattail reeds near marshes. Snow and ice cover the houses, giving them the appearance of an igloo, and accordingly they are called pigloos. The pigs burrow into their pigloos, and the reeds covered in snow insulate the pigs and help keep their body heat inside the structures. Canadians need to increase the wolf population, so they can huff and puff and blow the pig houses down. Unfortunately, this would face too much opposition from hunters and ranchers.

Wild boars are spreading throughout Canada. They can live in colder climates because they build nests out of cattail plants known as pigloos. The well insulated nests are kept warm by the beast’s own body heat.

Some Pleistocene Megafauna may have Survived in the Yukon until the Mid-Holocene

February 3, 2022

One of the first entries I wrote for this blog over 10 years ago highlighted a study of seda-DNA (short for sediment DNA) from cores taken in Alaskan permafrost. Permafrost preserves DNA of local animals that were shedding hairs, urinating, and defecating on the landscape. Different levels of the core were radio-carbon-dated, and scientists came to a surprising conclusion–mammoths and horses survived thousands of years after the youngest known sub-fossil evidence. Mammoths lived on mainland Alaska until 9700 years BP, and horses survived there until 7000 years ago. Recently, some of the same scientists conducted a similar study in the Klondike region of the Yukon, and they came to a similar conclusion. This study of 4 sites in the region was more extensive and also kept track of plant DNA, so changes in the environment could be detected. Apparently, mammoth, horses, and bison persisted in small refugial populations in the region thousands of years after the youngest known dated specimens in the paleontological record. They call this a temporal ghost range. They detected a DNA signal of these extinct and extirpated species from 9200 years BP to 5700 years BP, while paleontological evidence indicated they had disappeared from the region ~12,000 years ago. The authors of this study concede older sediment could have mixed with younger sediment, causing a mistaken observation, but they think this is unlikely because the samples were the same from 21 different cores taken from 3 different sites, and changes in plant composition were consistent with what they expected from unmixed sediment.

Chart showing temporal abundance of megafauna and shifts in climate. From the below reference.
Chart showing abundance of seda-DNA of plants and animals from 4 permafrost core sites in the Yukon. Most species of megafauna were more abundant when grassy steppe was widespread, but they seem to have still occurred in refugial populations long after the shift from grassy steppe to more mesic shrub and forest habitat. Also from the below reference.

Scientists hoped the study could shed light on why the grassy steppe ecosystem of the Late Pleistocene collapsed. There are 2 schools of thought. Dr. Guthrie believes increased precipitation and cloud cover brought on by climate change changed the environment from grassy steppe to mesic peat marsh, willow scrub, and spruce forest; thus, depriving grass-eating animals of their primary food source and causing their extinction or extirpation. Dr. Zimov believes the disappearance of the megafauna itself caused the transformation of the landscape. He thinks herds of large animals trampling, grazing, and defecating suppressed woody growth and maintained the grasslands. Humans overhunted megafauna into extinction in this scenario.

Data from this study can be used to support both arguments. The biggest decline in mammoth populations occurred about 20,000 years ago–long before the transformation of the mammoth steppe into present day environments. There is ephemeral archaeological evidence of people in North America then, and they might have started reducing mammoth herds. Also, mammoths, horses and bison declined about the same time Homo sapiens became more common. However, the final significant decline in megafauna populations did occur when the grassy mammoth steppe was in transition to a landscape dominated by woody vegetation.

I’ve long been convinced humans are completely responsible for the extinction of most, if not all, Pleistocene megafauna, even in this remote region. I think populations of grazing megafauna did decline in this region due to changes in climate. But grassy environments never completely disappeared, and in some areas these refuges were still capable of supporting smaller populations of grazers which did maintain small grasslands with their activities. These refugial populations could have expanded to repopulate the region given favorable changes in climate, like those that occurred periodically throughout the Pleistocene. However, man wiped out these interglacial refugial populations of mammoths, bison, and horses. If not for man, I think there still would be local populations of these species in the region, but they just wouldn’t be as abundant as they were during Ice Ages. They were not picky feeders and could subsist on some woody vegetation. Incidentally, there is fossil evidence of steppe bison (Bison antiquus) from central Canada (not exactly in the region but not on the other side of the continent either), dating to the mid-Holocene. See:

Reference:

Murchie, T. et. al.

“Collapse of the Mammoth Steppe in Central Yukon as Revealed by Ancient Environmental DNA”

Nature Communications Dec 2021

https://www.nature.com/articles/s41467-021-27439-6

Wolves and Spotted Hyenas Competed for Prey on the British Isles during Interstadials

December 16, 2021

Today, timber wolves (Canis lupus) and spotted hyenas (Crocuta crocuta) do not have overlapping ranges, but during the Pleistocene they co-existed throughout much of Eurasia. A recent study of bone chemistry from specimens of wolves and hyenas from 3 fossil sites located in southwestern England suggests they competed for the same prey items. Fossils from these 3 sites date to 3 different interglacial and interstadial climate phases. The oldest site yields fossils dating from between 220,000 years BP to 190,000 years BP. This was a warm interglacial, and grasslands were thought to be widespread here then. Fossil specimens from this site include elk, wild boar, mountain hare, lion, wolf, hyena, red fox, and cat. Wolves and hyenas primarily ate horse and hare during this time period. The 2nd oldest site yields fossils dating from 90,000 years BP to 80,000 years BP–an interstadial during the early Wisconsinian Ice Age when average temperatures temporarily reversed back to more temperate conditions. Fossils found at this site include bison, caribou, red fox, arctic fox, wolverine, brown bear, and wolf. Wolves primarily ate bison and caribou during this climate phase. The 3rd site yields fossils dating from 60,000 years BP to 25,000 years BP, a phase of rapidly fluctuating climates bouncing back and forth from cold stadial to warm interstadial. Fossils from this site include horse, wooly mammoth, wooly rhino, bison, caribou, hyena, wolf, hare, and elk. Wolves and hyenas primarily ate horse, rhino, and bison during this phase. Spotted hyenas disappeared from the British Isles during the Last Glacial Maximum when most of it was covered in glacial ice. Wolves persisted on the islands until man wiped them out during the 1700s.

Comparison between timber wolf and spotted hyena. Today, their ranges do not overlap, but they did occur together throughout Eurasia during the Pleistocene. They likely competed for the same prey items. Pleistocene hyenas outweighed wolves by about 50 pounds on average. I ripped this image off google images.
Map of fossil sites where wolf and hyena specimens used in the below referenced study were excavated. Image from the below referenced study.

Although I have no doubt wolves did compete with spotted hyenas during the Pleistocene, I am highly skeptical analysis of bone chemistry can accurately determine the former diets of these ancient animals. The limited sample size of fossil specimens may not reflect the diet of the entire population. Moreover, a study of moa coprolites from New Zealand determined the results of an isotope analysis did not match the contents of moa coprolites actually found. (See: https://markgelbart.wordpress.com/2016/06/24/trust-the-coprolites-not-the-stable-isotope-analysis/ ) In my opinion this study debunks the results of all studies using stable isotope analysis to determine the diets of ancient animals. The only sure way of knowing what an animal ate is to analyze the contents of their fossilized feces. I consider the bone chemistry studies to be interesting speculation but little better than wild guessing.

Reference:

Flower, L; D. Schreve and A. Lamb

“Nature of the Beast? Complex Drivers of Prey Choice, Competition, and Resilience in Pleistocene Wolves (Canis lupus 1754)

Quaternary Science Review 272 November 2021

New Species of Miocene Saber-tooth Recognized (Machairodus lahayishupup)

November 5, 2021

Scientists recently recognized a new species of saber-tooth cat from specimens found in museum collections. Specimens of this species were originally excavated from sites in Texas, Idaho, California, and Oregon. Although only 7 specimens of this species are known to science, scientists were able to diagnose it as a new species based on the dimensions of the arm bones. Skulls and fangs have yet to be found, and all we know about it comes from arm and jaw bones. Scientist gave the species the unpronounceable scientific name of Machairodus lahayishupup. One of the specimens was found on the Umatilla Indian Reservation, and the scientists decided to honor the Indians by giving it the name lahayishupup, meaning ancient cat in the Cayuse Indian language. I say thumbs down for giving it such an unpronounceable name.

Artist’s rendition of the newly recognized species of Miocene saber-tooth. This artist forgot to draw the fangs.
Fossilized arm bone of the Miocene saber-tooth.
Fossilized jaw bone of the Miocene saber-tooth. Skulls and fangs of this species have not been discovered yet.

Scientists believe the species lived from 9 million years BP to 5.5 million years BP during the late Miocene. Individuals averaged 600 pounds and may have reached weights of 900 pounds. Potential prey species in North America included rhinos, horses, tapirs, camels, and giant ground sloths. It was likely an ambush predator that lived in semi-tropical woodlands. Most of North America was semi-tropical then. At the time similar species occurred in Eurasia and Africa. This species may have been ancestral or related to the ancestor of the well known Smilodon fatalis and the lesser known Homotherium latidens both of the late Pleistocene.

Reference:

Orcutt, J. and J. Calede

“Quantitative Analysis of Feliform Humeri Reveal the Existence of a Very Large Cat in North America during the Miocene”

Journal of Mammalian Evolution (28) 2021