Archive for March, 2021

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

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Tegu Lizards (Salvator merianae) are Invading Georgia

March 18, 2021

You know who I hate (besides Trumpanzees)?  I hate the hypocritical sadistic do-gooders who hunt Burmese pythons in south Florida.  For generations the ecosystem there has been out of whack because large predators have been reduced or exterminated.  Finally, a new large predator has been introduced (though accidentally), but these stupid jerks are wiping them out too.  Burmese pythons can help control the overpopulation of raccoons and wild hogs in South Florida that destroy eggs of endangered species of turtles.  The snake-killers refuse to acknowledge this benefit, and instead they are doing their best to eliminate another large predator that simply is substituting for the wolves and cougars that humans also try to wipe out.  I hope these assholes fail.  I root for the snake.  In fact I hope 1 day a Burmese python squeezes the life out of a snake-killing hypocrite who is trying to exterminate them. I would celebrate the irony.  I’d love to write the headline “Burmese Python Euthanizes Human.”

The Argentine black and white tegu is another newly colonizing species (which alarmists call invasive) that has wildlife biologists hyperventilating.  This species is native to South America and a popular pet among reptile-lovers.  However, they grow to 3 feet long and reach weights of 15 pounds.  Pet-owners get tired of taking care of such a large lizard, and they release them into the wild.  Tegus established a breeding population in south central Florida where they’ve been munching down on alligator and turtle eggs for 20 years.  Over the past 3 years there have been over 50 sightings of tegus in Georgia, mostly in Toombs and Tatnall Counties.  To determine whether a breeding population exists in south Georgia, scientists conducted a study.  They set out 75 live traps in 3 different locations in those 2 counties for a couple of months.  The scientists caught 2 breeding age females in all that time, indicating to me that they are still uncommon but present.  The authors of the paper wrote they “euthanized” the lizards by shooting them with a .22 rifle.  I hate the word, euthanize, because it makes killing a creature sound sanitized.

Argentine Black And White Giant Tegu, Tupinambis Merianae Or.. Stock Photo, Picture And Royalty Free Image. Image 94513894.

Black and white tegu lizards, native to Argentina and other South American countries, have established a population in Florida and are invading Georgia.  Do-gooder assholes want to wipe them out, but I think for the most part they are harmless.

Native range map for black and white Argentine tegus.

Verified and unverified sightings of tegu lizards in Georgia + trapping sites of the below referenced study.  .

Map of verified and unverified sightings of tegus in Georgia and Florida.  Surprisingly, some of them have been from quite far north in Georgia.  Tegus are partially warm-blooded and can dig burrows, helping them survive in cooler climates.  Map also from the below referenced study.

Most of Georgia is ideal habitat for tegu lizards.  They are partially warm-blooded and can did burrows to escape cold and hot weather.  Females lay about 30 eggs, and the young become full grown and sexually mature in 2 years.  They are also omnivorous, eating insects, other arthropods, small animals, eggs, and fruit.  The stomach contents of 7 tegu lizards trapped in Georgia included blackberry, strawberry, insects, other arthropods, crayfish, wood frogs, and a toad.  This list hardly sounds like an animal that is destabilizing the environment.  Wildlife biologists are concerned the lizards might eat eggs of the endangered gopher tortoise, and they have been found in gopher tortoise burrows, but native raccoons are much more abundant and have hardier appetites.  If gopher tortoises can co-occur with raccoon predation, they can endure the impact of a few lizards.  Unlike Burmese pythons, tegu lizards are much more vulnerable to native predators.  I’m sure bobcats, coyotes, hawks, owls, and snakes can control their numbers.

Reference:

Haro, D.; et. al.

“Evidence for an Established Population of Tegu Lizards (Salvatore merianae) in Southeastern Georgia”

Southeastern Naturalist (19) 4 2020

Deinosuchus rugosus Given a New Scientific Name–D. Schwimmeri

March 11, 2021

My wife took a geology class 40 years ago at Columbus State University, and it was taught by David Schwimmer who now has the honor of having an extinct species of crocodylian named after him.  The paleontologists who named the species after him consider it a new species (or species novum), but it is really not a species new to science.  The first scientist to name the species gave it the scientific name Deinosuchus rugosus.  However, the type specimen used to name the species is not considered diagnostic as it could represent any of the 3 known species of Deinosuchus.  So they used other more complete specimens to describe the anatomy of the species, and they decided to give it the scientific name D. schwimmeri after David Schwimmer who published a book about Deinosuchus during 2002.

Species named after Columbus State professor David Schwimmer | Columbus  Ledger-Enquirer

David Schwimmer of Columbus State University, my wife’s college geology professor.  He wrote a book about Deinosuchus, a giant extinct alligatoroid.  Deinosuchus rugosus has been renamed in his honor as D. schwimmeri.

Feces, Bite Marks Flesh Out Giant Dino-Eating Crocs

Deinosuchus preyed on tyrannosaurs and other dinosaurs.

Fossil evidence suggests there were 3 species of Deinosuchus living in North America during the late Cretaceous from ~80 million years BP-~73 million years BP.  The North American continent was split into 3 land masses by the Western Interior Sea then.  D. schwimmeri is the species that lived on the eastern part of North America, and D. riograndis lived on the western part.  D. hatcheri, a poorly known species, also lived on the western part.  D. riograndis tended to grow larger than D. schwimmeri.  All species of Deinosuchus were 36 foot long 12,000 pound monsters that ate Tyrannosaurus rex for breakfast.  Fossil specimens of Deinosuchus have been found in Georgia, New Jersey, North Carolina, Alabama, Mississippi, Texas, Utah, Nebraska, Wyoming, Montana, and Mexico.  Scientists aren’t sure how Deinosuchus came to live on both sides of the Western Interior Sea.  They likely were saltwater tolerant and perhaps island-hopped from 1 side to the other.  Alternatively, when the Western Interior Sea flooded the Great Plains, the 2 founding populations were separated.

Deinosuchus is considered an alligatoroid or in other words they are thought to have been more closely related to alligators than crocodiles.  They were not ancestral to modern alligators.  Instead they were related to the direct ancestor of modern day alligators.

References:

Gossette, A; and C. Bracho

“A Systematic Review of the Giant Alligatoroids Deinosuchus from the Cretaceous of North America and its Implications for the Relationships at the Root of Crocodylia”

Journal of Vertebrate Paleontology 40 (1) 2020

Schwimmer, David

King of the Crocodylians: The Paleobiology of Deinosuchus

Indiana University Press 2002

 

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