If I Could Live During the Pleistocene Part XII–My Mammal Checklist

I have a recurring fantasy (and it’s an ongoing irregular series on this blog) that I’ve found a time tunnel allowing me to travel back and forth from the present day to 36,000 years BP.  The site at the other end of the tunnel is located at what today is Elbert County, Georgia about 1 mile north of the Broad River and 2 miles west of the Savannah River, and at this location I’ve established a homestead.  I produce all my own food here, growing vegetables and fruits and raising milk cows, geese, chickens, and bees; so I rarely need to return to the present day for supplies.

Location of my imaginary Pleistocene homestead, 36,000 BP.

Varied pristine environments untouched by man offered many different habitats for wildlife here.  (Homo sapiens probably didn’t reach North America until 20,000 BP at the earliest.)  Interstadial climatic conditions prevailed 36,000 years ago–a warm spell between Ice Ages.  Oak trees predominated over pine, a situation that was reversed during cold stadials.  In the vicinity of my imaginary homestead there are moist slope forests consisting of beech, hickory, a variety of oaks, and walnut; open old growth woodlands composed of black oaks, red oaks, jack pine, and shortleaf pine; dry chestnut ridges; natural meadows; canebrakes; freshwater marshes; clear fish-filled rivers with lots of rocky shoals; creek bottoms laced with beaver ponds; brushy areas where storm-downed  trees resulted in open canopies; and recently burned over areas with dense stands of young trees.

In my imaginary life as a Pleistocene homesteader, I’ve surveyed the wildlife and produced a checklist of mammal species that I’ve collected or observed. The large animals are easy to see and catalogue, but the smaller ones are harder to collect and identify.  At night I set mist nets to capture bats–a more humane method than the one Frances Harper used in the early 20th century when he surveyed bats in the Okefenokee by smacking them down with a fishing rod.  I used live traps for small ground dwelling mammals.

Mist net for catching bats.

H.P Sherman trap for catching small mammals alive.

Below is a checklist of the mammals that I would probably collect or observe in this region during this time period.  I put question marks by the species that I might or might not find.  The fossil record in east central Georgia is very meager, and even in the surrounding states, it’s incomplete.  This checklist is simply an educated guess.

1. Opossum–Didelphis virginianus: Probably less common than today because of the abundance of mid to large-sized carnivores.

2. Southeastern shrew–Sorex longirostis

3. ?Smoky shrew?–Sorex fumeus

4. ?Longtail shrew?–S. disper

5. ?Pygmy shrew?–Microsorex hiyi: None of these 3 species of shrew are known in this region today, but they are known to have had wider ranges during some climatic phases of the Pleistocene.  At least one of these species might have occurred in east central Georgia then.

6. Least shrew–Cryptotis parva

7. Short-tailed shrew–Blarina brevicauda

8.  Star-nosed mole–Condylura cristata

9. Eastern mole–Scalopus aquaticus

10. ?Vampire bat?–Desmodus stocki–Lived in Georgia during warm interglacials.  Climate may have been too cold 36,000 years ago here.

11. Small footed myotis–Myotis leibi

12. Indiana myotis–M. sodalis

13. Gray myotis–M. grisecens

14. Little brown myotis–M. lucifruga

15. Southeastern myotis–M.austrariparius

16. ?Silver haired bat?–Lasionycteris noctivagus

17. Eastern pipistrelle–Pipistrellus subflavus

18. Big brown bat–Eptesicus fuscus

19. Hoary bat–Lasiurius cinereus

20. Red bat–L. borealis

21. Yellow bat–L. intermedius

22. Evening bat–Nycterius humeralis

23. Rafinesque’s big eared bat–Plectocus rafinesquis

23. Brazilian free-tailed bat–Tadarida brasiliensis: This species no longer occurs in this region.  It had a wider range before the Last Glacial Maximum and has yet to recolonize much of its former range.  It may do so in the future.

24. Northern pampathere–Holmesina septentrionalis: A 300 pound grass-eating armadillo that probably survived cold spells by digging underground burrows.

25. Beautiful armadillo–Dasypus bellus: As I’ve speculated in a previous blog entry (https://markgelbart.wordpress.com/2012/08/19/is-the-9-banded-armadillo-dasypus-novemcinctus-a-dwarf-mutation-of-the-pleistocene-species-dasypus-bellus/), I hypothesize the modern 9 banded armadillo is a dwarf mutation of this supposedly extinct species.

26. Jefferson’s ground sloth–Megalonyx jeffersonii

27. Harlan’s ground sloth–Glossotherium harlani: Jefferson’s prefered woodlands; Harlan’s preferred grasslands.

28. Fisher–Martes pennanti: I think this species would have a wider modern range, if not for its high quality fur.  Fisher skeletel material has  been found in the fossil and archaeological record of north Georgia.

29. Long tailed weasel–Mustela frenata

30. ?Badger?–Taxidea taxus:  There may or may not have been enough pure grassland in this region then to support a population of this prairie-loving  species.

31. Mink–Mustela vison

32. River otter–Lutra canadensis

33. Spotted skunk–Mephitis putorius

34. Striped skunk–Mephitis mephitis

35. Hog-nosed skunk–Conepatus leuconotus: This is another species that had a wider range during the Pleistocene.  The desert grassland habitat it requires completely disappeared in this region during the Holocene.

36. Coyote–Canis latrans

37. Dire wolf–Canis dirus: Probably one of the most common large carnivores in the region then.

38. ?Dhole?–Cuon alpinus: Dhole fossils have only been found at 2 sites in North America in Mexico and Alaska.  This species may have been more widespread than the fossil record indicates. See https://markgelbart.wordpress.com/2011/06/01/did-the-dhole-cuon-alpinus-range-into-southeastern-north-america-during-the-pleistocene/

39. Gray fox–Urocyon cineaoargenteus

40. Red fox–Vulpes vulpes

41. Raccoon-Procyon lotor

42. Florida spectacled bear–Tremarctos floridanus: This species likely didn’t hibernate and required year round forage.  It may have been as common as the black bear in Florida and the coastal plain of  the south where winters were especially mild but less so in the piedmont and mountains.

43. Giant short-faced bear–Arctodus simus: Probably a wide ranging occasional animal that would have been scary to encounter.  A kleptoscavenger that drove other predators from their kills.

44. Black bear–Ursus americanus: Probably very common in east central Georgia then.  Pleistocene black bears grew as large as grizzlies, and I hypothesize were more aggressive than they are today thanks to the big cats below.

45. Saber-tooth–Smilodon fatalis: I would have loved to have seen one of these alive and in action.

46. Scimitar-tooth–Dinobastis serum: Ditto.

47. ?American lion?–Panthera atrox: A denizen of open grassland habitat.  Unknown whether enough grassland existed to support this species in east central Georgia 36,000 BP, but it did colonize Florida during the LGM when drier conditions fostered more grassland.

48. Jaguar–Panthera onca: Probably the most common big cat in this region then.

49. Cougar–Puma concolor

50.? Margay?–Leopardus amnicola: An arboreal cat that was common and widespread in southeastern North America during the Sangamonian Interglacial.  It’s difficult to determine whether it still survived in the region 36,000 BP.  Winters may have gotten too cold by then.

51. Bobcat–Lynx rufus

52. Woodchuck–Marmota monax

53. ?13-lined ground squirrel?–Spermophilus tridecemlineatus: Difficult to determine if there were enough relic grasslands to support a population of this species in this region during this climatic phase.

54. Eastern chipmunk–Tamias striatus

55. Giant chipmunk–Tamias aristus: Fossils of this species have been found at sites dating to the Sangamonian Interglacial.  It may not have become extinct until the Last Glacial Maximum.  I hypothesize it was a year round forager, unlike its smaller cousin which hibernates. See https://markgelbart.wordpress.com/2011/01/20/tamias-aristus-the-extinct-kicked-up-version-of-the-eastern-chipmunk/

56. Fox squirrel–Scirius niger

57. Gray squirrel–Scirius carolinensis

58. Red squirrel–Tamiascirius hudsonicus

59. Southern flying squirrel–Glaucomys volans

60. Eastern pocket gopher–Thomomys orientalis

61. Southeastern pocket gopher–Geomys pinetus

62. Giant beaver–Casteroides dilophidus: Giant beavers favored treeless marshes, but may have occasionally built dams.  Modern beavers create habitat favorable to giant beavers by felling lots of trees and the 2 species did not compete as some scientists erroneously claim.  They ate different foods.

63. Beaver–Castor canadensis

64. Rice rat–Oryxomys palustris

65. Eastern harvest mouse–Reithrodontomys humulis

66. Deer mouse–Peromyscus manisculatus

67. Old field mouse–P. polionatus

68. White-footed mouse–P. leucopus

69. Cotton mouse–P. gossypinus

70. Golden mouse–Ochrotomy nuttali

71. Cotton rat–Sigmodon hispidus

72. Red-backed vole–Clethritonomy gapperi: No longer occurs this far south.

73. Meadow vole–Microtus pennsylvanius

74. Pine vole–M. pinetorum

75. ?Prairie vole?–M. ochrogaster

76. ?Florida muskrat?–Neofiber alleni: This species formerly had a much wider range.  They require year round green vegetation.  Difficult to determine exactly when they disappeared from east central Georgia.

77. Muskrat–Ondatra zibethicus

78. Southern bog lemming–Synaptomys cooperi

79. Meadow jumping mouse–Zapus hudsonicus

80. Porcupine–Erethizon dorsatum: Had a wider range during the Pleistocene.  Archaeological evidence suggests Indians overhunted them in the southeast.

81. Capybara–Hydrochoerus holmesi: 2 species of capybaras lived on the coastal plain of Georgia during the Pleistocene.  It’s unknown exactly how far inland they ranged. They favor grassy flooded marshes alongside rivers.

82. Eastern cottontail–Sylvilagus floridanus

83. Swamp rabbit–S. aquaticus

84. Horse–Equus ferus

85. Half-ass–Equus scotti

86. Tapir–Tapirus veroensis

87. Long-nosed peccary–Mylohyus nasatus: Probably one of the most common large mammals in east central Georgia then and would be common table fair for a Pleistocene homesteader.

88. Flat-headed peccary–Platygonnus compressus

89. Large-headed llama–Hemiauchenia macrocephala

90. Stout-legged llama–Paleolama mirifica

91. White-tailed deer–Odocoileus virginianus: Probably at least as common then as today and an important part of my diet at my Pleistocene homestead.

92. ?Caribou?–Rangifer tarandus: Fossils of this species dating to the LGM have been found as far south as Charleston, S.C.  There were probably large herds of caribou seasonally migrating just south of the glacial margin which at the time was near the Canadian border.  Some of these herds evidentally broke off and wandered south.

93. ?Stag-moose?–Cervalces scotti: May have been another rare straggler that was more common farther north.

94. ?Elk?–Cervus elephus: Occurred in central Georgia as recently as the 18th century.  Genetic evidence suggests elk didn’t cross the Bering land bridge until ~15,000 years BP, but perhaps a different lineage occurred here then.

95. ?Helmeted muskox?–Bootherium bombifrons: Colonized Louisiana and Mississippi during the LGM, but fossils are unknown this far southeast. See https://markgelbart.wordpress.com/2011/07/27/the-south-central-salient-of-the-helmeted-musk-ox-ovibos-cavifrons-or-bootherium-bombifrons/

96. Long-horned bison–Bison latifrons: Probably fairly common here then.

97. Mastodon–Mammut americanus: Were either seasonal or year round residents here.

98. Columbian mammoth–Mammuthus colombi: Ditto.

99. ?Gompothere?–Cuvieronius tropicalis: Another elephant-like mammal that lived in the southeast.  Climate may have become too cold for this species in this region by 36,000 years BP.

100. 9-banded armadillo–Dasypus novemcitus: Genetic evidence suggests it co-occurred with the beautiful armadillo.

Ice Age-Influenced Avian Speciation in North America

The evolution of a new species requires geographical or ecological isolation from its parent species.  In nature this can occur in any number of ways–the uplifting of a mountain chain, a rise in sea level that creates an island, climate-induced ecological change, individual differences in foraging preferences within a population., etc.  Scientists have even created new species of bacteria, fruit flies, and worms in the lab by isolating populations of these organisms from their parent populations.  After many generations of reproductive isolation, the new species will not or can not successfully mate with members of their parent population when reintroduced.  In North America there are many examples of eastern and western bird species that are so similar it’s obvious they evolved from a single common ancestor.  The geographical barrier that isolated eastern and western avian populations is well known.

During the Miocene forested environments covered most of the North American continent.  But early during the Pliocene, about 5 million years ago, Ice Ages began to occur.  The middle of the continent became desert grassland that was unsuitable habitat for forest birds, thus isolating eastern populations from western populations.  In 3 cases, this isolation resulted in subspecific differences.  The common flicker (Colaptes auratus) includes the yellow shafted eastern form and the red shafted western form.  The yellow rumped warbler (Dendroica coranata) is split into the eastern myrtle warbler and the western Audubon’s warbler.  The dark-eyed junco (Junco hyeanalis) includes the eastern slate-colored and the western Oregon.  Ornithologists formerly thought the eastern and western forms of these 3 were separate species, but it was discovered they freely interbreed in regions where their populations overlap, despite differences in physical characteristics.

The common flicker. Unlike most woodpeckers, it forages on the ground, feeding on ants and beetles, rather than pecking wood for insect borers.  There are always a few of these nesting in my neighborhood during spring and summer.  The eastern and western forms of this species were formerly thought to be different species.  Geographical isolation resulted in subspecific differences but not complete speciation.

There are at least 22 examples of eastern species of birds with a similar but distinct western counterpart including eastern and western peewees, eastern and western bluebirds, scarlet and western tanagers, eastern and western screech owls, among many others.  These birds are considered distinct species.

Eastern bluebird.  I also see a few of these in my neighborhood during spring and summer.

Range maps of eastern and western bluebirds.  Both species descend from 1 common ancestral species that formerly occurred across the continent before Ice Ages caused unsuitable desert grassland habitat to replace forested habitat in the middle of the continent.

During the present interglacial, forested habitat is once again becoming more widespread.  Moreover, man often plants trees in region that were once prairie, and he suppresses natural fires necessary for the development of grasslands.  As a result, similar eastern and western species of birds are expanding their ranges and occasionally, they come into contact and hybridize.  Hybridization is another mechanism that plays a role in the evolution of new species.  Similar species that were once reproductively isolated but come into contact again may backcross and evolve into yet another new species.  An estimated 9% of bird species are known to hybridize with other bird species.  (Homo sapiens may be a hybrid species.  DNA evidence suggests some Eurasian Homo sapiens have some Homo neanderthalis ancestry.)

Eastern and Western Screech Owl hybrid.  These 2 species were isolated during Ice Ages by a desert grassland barrier.  Now, they are both expanding their ranges and reuniting.  Hybridization is another mechanism that can result in new species.

Hybridization can endanger a species through genetic swamping.  Barred owls (Strix varia) are expanding their range into the habitat of northern spotted owls (Strix occidentalis).  Environmentalists saved spotted owls from clear-cutting, but within the last 30 years, barred owls have successfully invaded the Pacific northwest.  Barred owls usually just eat the smaller spotted owls, but they also mate with them–47 hybrids have been reported.

Ice Age glaciers also provided a barrier that geographically isolated 7 ancestral populations of birds, resulting in 14 species.  Glacial barriers split northern shrikes from loggerhead shrikes, Bohemian waxwings from cedar waxwings, 3-toed woodpeckers from black- backed 3-toed woodpeckers, boreal owls from saw-whet owls, black billed magpies from yellow-billed magpies, northern goshawks from Cooper’s hawks, and boreal chickadees from black-capped chickadees.  During Ice Ages, northern shrikes, Bohemian waxwings, 3-toed woodpeckers, boreal owls, black-billed magpies, northern goshawks, and boreal chickadees found refuge in Beringia and Eurasia, while loggerhead shrikes, cedar waxwings, black-backed 3-toed woodpeckers, saw-whet owls, Cooper’s hawks, and black-capped chickadees lived in North America south of the glaciers.

Top: Loggerhead shrike (Larius ludovicianus).  Bottom: Northern shrike (Larius excubitor).  They both descend from 1 common species with a circumpolar distribution.  Ice Age glaciers separated this ancestral population, resulting in 2 distinct species.  Northern shrikes usually have gray over their bills, while loggerhead shrikes usually have black over their bills.  The former also have larger bills.

Since the end of the Ice Age, the Eurasian species mentioned above have recolonized much of Canada but maintain separate breeding grounds from their American sister species.

References:

Newton, Ian

Speciation and the Biogeography of Birds

Elselvier Science 2003

Pielou, E.C.

After the Ice Age

The University of Chicago Press 1991

Note: * I discovered plagiarism in the book written by Ian Newton.  He plagiarized a passage from After the Ice Age and didn’t even cite that work in his book.*  Wow! What lazy scholarship.  He didn’t even bother to put the original awkwardly written passage in his own words.

The Windy Ice Ages

I love a good brisk wind.  Cool windy days seem to put an extra bounce in my step when I do my near daily 3 or 4 mile run up and down the street in front of my house.  And I love hearing the sound of the wind blowing against the house on a winter’s night while I’m snug under the comforter, dreaming of big-breasted women.  Wind is another reason I wish I could jump in a time machine and take a trip back to the Ice Ages of the Pleistocene because when massive glaciers covered most of what today is Canada, the earth heated even more unevenly than it does today, resulting in windier conditions everywhere.

Scientists measure wind in meters per second.  In modern day Georgia and South Carolina, winds average between 1.3-2.2 meters pers second, but during the Last Glacial Maximum winds averaged 4-6 m/s–more than double those of today.  As I’ve written in previous blog entries (See https://markgelbart.wordpress.com/2011/11/07/when-ice-age-georgia-became-desert-like/ and See https://markgelbart.wordpress.com/2013/03/10/when-sand-dunes-buried-herds-of-flat-headed-peccaries/), Ice Age winds often pushed eolian sand dunes across the landscape.  The climate was much drier then because the expanding glaciers locked up so much of earth’s moisture.  The modern precipitation/evapotranspiration ratio in southeastern North America is 1.23.  (Evapotranspiration is the sum of evaporation and plant transpiration.)  But during the LGM it was less than .3 or about 25% that of today.  Precipitation averaged about 33% less than that of today as well.  Moreover, the ocean receded and rivers had to flow longer distances to reach the sea.  As a result, rivers shrank in size, and riverine sand became exposed.  Strong winds pushed these sands into dunes.  Unlike modern day winds which directionally vary according to the seasons, Ice Age winds were consistently west/southwesterly and pushed these dunes to the northeast sides of rivers.  This is the origin of most of the sandhills found in the southeast today.  Modern day winds are not strong enough to  push sands into dunes or as geologists say they could not maintain a “sustained eolian mobilization.” 

The precipitation/evapotranspiration ratio was much lower during the Ice Age than it is today, resulting in a more sparsely vegetated landscape.

Geologists believe these eolian sand dunes were once u or v-shaped in front. The dunes were unvegetated but had partly vegetated parallel arms upwind from the dune fronts.  One such dune is located east of the Savannah River in Jasper County, South Carolina.

Jasper County, South Carolina

Exposed Savannah River Dune.  There are many dunes like this located on the northeast side of southeastern rivers.

The Savannah River dune formed between 40,000 BP-19,000 BP.  It alternated between active and inactive stages in concert with variations in precipitation rates.  The surrounding area around the dune was not barren but consisted of grasslands and open woodlands, composed  mostly of pine and oak with less floral species diversity than modern day forests.  Vegetation was less dense than it is today.

At the end of the Ice Age, glaciers began melting, thus releasing moisture into the atmosphere.  Plants took root on the dunes and started holding them down, rendering them inactive.  During the Younger Dryas about 13,000 BP, climate suddenly became as cold and dry as it was during the LGM but just for a few hundred years.  Several smaller dunes formed again, but since then, all of the sand dunes in southeastern North America have become inactive due to the increase in precipitation and the decrease in wind velocities.

Reference:

Sweezey, Christopher; et. al.

“Quaternary Eolian Dunes in the Savannah River Valley, Jasper County, South Carolina”

Quaternary Research (80) 2013

Gila Monster Kin Roamed All Over Southeastern North America During the Miocene

Up until 2009, scientists thought the only venomous lizards in the world were 2 closely related species of helioderms–the Gila monster (Helioderma suspectum) and the Mexican beaded lizard (Helioderma horridum).   That all changed when an Australian scientist, Dr. Bryan Fry, discovered Komodo dragon (Varanus komodoensis) venom glands.  Formerly, scientists assumed bacterial infection from a Komodo dragon’s bite doomed its prey, but Dr. Fry’s new studies found that gaping wounds combined with blood clot-destroying venom caused the Komodo dragon’s prey to expire. Moreover, he examined the bacteria in a Komodo dragon’s mouth and found fewer species of toxic bacteria than are found in a human’s mouth–debunking the old hypothesis that septicemia caused its prey’s death.  Water buffalo bitten by Komodo dragons do die of toxic infection, but they get the infection from retreating into fecal contaminated water holes.  Smaller prey such as deer or pig actually succomb to the Komodo dragon’s venom.  Since this discovery, other scientists have discovered venom glands in close to 100 species of lizards including other monitors (varanids), iguanas (iguanids), and dragon lizards (adamids).

All the species of lizards that have venom glands share a close ancestry with snakes and prehistoric mosasaurs.  In many cases such as the mostly vegetarian iguanas, the venom glands seem to serve no purpose and are probably just vestigial.  The helioderms share a close ancestry with Old World monitor lizards, but enough differences in anatomy along with the wide geographic disparity between the 2  have convinced scientists that Gila monsters and Mexican beaded lizards should be classified within their own unique family.

Geographical range of the 2 subspecies of Gila Monster.  Helioderms are confined to America while varanids are restricted to Africa, Asia, and Australia.

Gila monsters are surprisingly active and able to climb trees and raid bird’s nests.

https://www.youtube.com/watch?feature=player_detailpage&v=jyqLLdufjD0

Above link is a youtube video of a confrontation between a ground squirrel and a Gila monster.

Mexican beaded lizard.  Note the swollen tail.  Helioderms live in underground burrows most of the year and survive on fat stored in their tails.  No wonder they survived the K-T impact that wiped out the dinosaurs.

The most notable physical characteristic distinguishing helioderms from other lizards is the bony ossicles in their skin, a feature no other lizards have.  Like the varanids, they are large lizards.  Gila monsters grow to 2 feet long, while Mexican beaded lizards grow even larger to 3 feet long.  Both spend most of their lives in underground burrows but emerge seasonally to feed and mate.  They only eat 5-10 times a year, primarily upon bird’s eggs and nestlings, but they will also take small mammals, frogs, other lizards, carrion, and insects.  They will climb trees to raid bird’s nests.  Their venom is not used in hunting.  Most of their prey is small enough to simply be crushed between their jaws.  Their venom is likely a defensive adaptation, and their distinctive coloration serves as a warning to predators.  Nevertheless, they occasionally fall victim to coyotes and birds of prey.

Helioderm venom contains exanatide, an enzyme resembling the peptide that helps humans digest glucose.  It’s an ingredient in a drug used to help manage diabetes.  Helioderms rarely bite humans, and there have been no known fatalities, though the bite causes victims to suffer sickness and discomfort that generally lasts 5 days.

Species of helioderms lived during the Cretaceous when they probably fed upon dinosaur eggs and hatchlings.  Various unknown and poorly known extinct species of helioderms lived all across southeastern North America and probably most of the continent during the Miocene.  Fossils of Helioderma texana have been found in Texas.  A jawbone and a few leg bones of helioderms were found at 2 sites in north Florida, but it wasn’t enough material to establish what specific species the specimens belonged to.  At the Gray Fossil Site in Tennessee, scientists identified the bony ossicles of a helioderm–also insufficient evidence to identify the specimen at a species level.  Seasonally subfreezing climates began to occur across most of North America early during the Pliocene.  This eliminated much habitat for helioderms and probably resulted in the extinction of several species.  Today, the only surviving species of this once more widespread genera live in relatively frost free regions of southwestern North America.

Fossil bony ossicles of a helioderm lizard found at the Gray Fossil Site in Tennessee.

See also: https://markgelbart.wordpress.com/2010/03/31/the-real-dragon-of-the-pleistocene-megalania/

The Faunal Diversity of Pleistocene North America was less than that of Modern Day Africa

Pleistocene North America has often been described as having a bestiary resembling that of the African continent.  I’ve probably even used this description myself.  This is not accurate.  The North American continent was home to a healthy ecosystem consisting of megafaunal herbivores, carnivores, and scavengers.  It was a vast unpeopled wilderness until man arrived and brought destruction upon many of the largest and most impressive species.  Yet, in species diversity, the North American Pleistocene doesn’t even come close to rivaling that of Africa.  There are 1100 species of mammals native to Africa compared to the 540 species of native North American mammals that lived during the Pleistocene–nearly double the number of species.  Yes, North America hosted 4 kinds of elephants, the unique giant ground sloths and armadillos, bison, camels, horse, peccaries, bears, big cats, and wolves. But Africa has 2 kinds of elephants, 2 kinds of rhinos, hippos, giraffes, hogs, zebras, and dozens of bovid species also known as antelopes.  Aardvarks and pangolins are every bit as unique as the edentates.  There are 60 species of carnivores, and 64 species of primates, including 5 species of apes. Until man arrived, North America’s Pleistocene had zero primates.

Giraffes.  We are fortunate that such a prehistoric-looking mammal still survives.  Toxodons, more massive but also with long necks, did live as far north as Mexico during the Pleistocene.  North America also hosted a long-necked species of camel during the Miocene.  The North American Miocene was more comparable to modern Africa in mammal species diversity than the Pleistocene.

Pangolin–every bit as primitive and unique as armadillos and ground sloths.

Mixed herd of elephants and wildebeest.  Wildebeest are one of many species of bovids.  Africa far outnumbers North America in species of bovids.  Antelope diversity here is amazing.

Baboon.  Africa outnumbered North American Pleistocene species of primates 60-1.

Africa is home to more species of mammals than any other continent.  Most of the African continent has never been subject to the seasonal subfreezing climates that have occurred in North America and Eurasia since early during the Pliocene.  Fewer species of mammals evolved the ability to survive in subfreezing climates, and I think this explains why Africa has a greater diversity of mammal species than any other continent.  This may not have always been the case.  During the Miocene (25 million BP-5 million BP), subfreezing climates did not occur over most of North America.  North America hosted at least 68 genera of hooved mammals during the Miocene compared with just 26 genera of hooved mammls during the Pleistocene.  It’s possible North American mammal diversity was equal to or higher  than in Africa during the Miocene.  So one could accurately describe the bestiary of Miocene North America as being similar to that of Africa.

***

Not many end Pleistocene extinctions occurred on the African continent.  I think there are 2 reasons: a) tropical diseases formerly kept human populations lower in Africa than in other continents, and b) the animals living in Africa co-evolved with humans and were better adapted to avoid human hunters.  Of the handful of large Pleistocene mammals that did become extinct in Africa, scientists dispute whether some of them are actually different from living modern species.   The Cape horse (formerly Equus capensis) is now thought to be the same species as the living Grevy’s zebra.  The long-horned African buffalo (Pelobovirus antiquus) may have been a distinct species or just a large morph of the modern day water buffalo–its status is in dispute.  There was a large species of hartebeest (Megalotrigus priscus) that may have been overhunted into extinction.  The blue antelope (Hippotragus leuphagus) became extinct in 1800, possibly due to competition with domestic cattle.

The Sahara alternates cyclically between desert and well-watered savannah, depending on variations in earth’s tilt which change where oceanic monsoons bring precipitation to the African continent.  The Sahara has been in a desert cycle since 5000 BP.  During moist climatic cycles, some Eurasian species of mammals such as the extinct Eurasian rhino (Dicerorhinus kuchenbergensis), and the extinct Irish elk (Megalocerus) lived alongside giraffes, hippos, lions, and crocodiles in North Africa.  These species became extinct in Eurasia during a Sahara dry spell and couldn’t recolonize North Africa 12,000 years ago during the most recent moist phase of climate.

The giant deer or Irish elk–a widespread species in Eurasia.  The last known population of Irish elk lived in the Ural Mountains of Russia ~7700 BP.  This species periodically colonized North Africa when the Sahara desert became savannah following changes in the latitude of the monsoons.

Archaic species of hominids may have caused the early Pleistocene extinctions of several mid-sized carnivores that occupied the same omnivorous scavenging niche that early man did. A giant bear otter (Enhydridion dikikea) and a civet cat are among those mammals that Homo habilis may have extirpated.  Homo erectus may have wiped out a species of giant baboon (Therepithecus oswaldi), and there is archaeological evidence of a mass kill site.  It appears that a band of club-wielding Homo erectus slaughtered a whole troop of giant baboons.  Interestingly, the skull fractures indicate 93% of the blows were struck from right-handed men–the exact percentage of right-handers in the present day population. I also think humans are responsible for the extinction of Africa’s saber-tooth (Megentereon).  I hypothesize saber-tooths were a stubborn species that refused to give way when defending a carcass, unlike lions and hyenas that do retreat before a band of noisy stick-wielding hominids.

Fossil skull of extinct bear otter.  Lars Werdelin, a Swedish scientist, thinks Hominids outcompeted the giant bear otter and other mid-sized African carnivores into extinction during the late Pliocene and early Pleistocene.

The Biogeography of the Malay Archipelego

Alfred Wallace explored the Malay Archipelego between 1854-1862, collecting over 125,000 specimens of mammals, birds, reptiles, insects, and molluscs that he sent back to England.  The majority of these species were unknown to science then.  He knew about Darwin’s Theory of Evolution before a reluctant Darwin  published his Origin of Species.  Darwin was a high society gentleman, hesitant to publish his provocative theory, but Wallace wholeheartedly endorsed his theory from evidence he gathered on his natural history expeditions, and he was going to begin discussing Darwinism in his own scientific papers.  This prodded Darwin into finally publishing his theory.  Alfred Wallace, who was more of a working class guy, didn’t care what old fuddy duds thought about the new theory.  He deserves as much credit as Darwin for introducing the fundamental framework of all biological science, but he is relatively unknown by comparison.

Alfred Wallace discovered an interesting faunal partition in the Malay Archipelego, a geographical area including hundreds of islands extending for 4000 miles.  The birds and mammals on the western islands resemble Asian species, while those on the eastern islands resemble Australian species.  He noted the seas between islands with similar species of wildlife were shallow enough for ships to anchor.  He correctly came to the conclusion that formerly a landbridge once connected eastern islands to Australia, and another landbridge connected western islands to Asia.  The islands of Bali and Lombock are adjacent with only a few miles separating them, yet the avifauna on the 2 islands differs in the extreme.  Not coincidentally, the depth of the sea between the 2 precluded the possibility they were ever joined.  The most common birds on Bali–yellow breasted weavers, black grasshopper thrushes, rosy barbets, and 3-toed woodpeckers–were of Asian origins and totally absent on Lombock, while the 2 most common birds on Lombock–white cockatoos and honeysuckers–were of Australian affinities and were absent on Bali.

Map of the Malay archipelego.  During Ice Ages sea level fell.  Some of the islands were connected to Asia via a landbridge, while others were connected to Australia.  The present day flora and fauna on the islands that were connected to Asia show affinities to that continent, while the eastern islands have flora and fauna with Australian affinities.

Western Malaysian islands host Asian species of wildlife such as elephant, rhino, buffalo, deer, pig, tapir, macaque, orangutan, cats, dogs, and rodents.  None of these mammals were native to eastern islands, though deer, pig, and macaque have been introduced by man to some of them.  Possums, and in New Guinea, tree kangaroos are the only native mammals on the eastern islands other than bats.  Even the bird life between the 2 groups of islands is in contrast.  Of course, shorebird species common to both are found, but the upland species are quite different.  Woodpeckers and pheasants, common birds on western islands, are unknown on eastern islands.  Conversely, the eastern islands have unique species of birds not found anywhere else on earth aside from Australia.  Cockatoos, cassowaries, brush-tongued lories, moundbuilders, honeysuckers, and birds of paradise are some of the birds with Australian affinities, not found on western islands.

The red buffed woodpecker (Meiglyptes tukki.)  Woodpeckers are common on the Asian side of the Malay Archipelego but are absent from the Australian side–evidence of 2 separate landbridges during the Ice Ages.  Despite their ability of flight, forest birds rarely fly over ocean barriers.

The black banded squirrel (Callosciurus orestes).  Squirrels are common on the islands that were once connected to Asia, but are absent from islands once connected to Australia.

The Sulphur Crested cockatoo (Cacatua galerita), a bird with Australian affinities found on eastern islands of the archipelego. 

The Sulawesi cuscus–a type of possum with Australian affinities.  Possums are the only native mammals found on the eastern islands of the archipelego, other than bats.  Tree kangaroos are found on New Guinea.

During the Pleistocene it would have been possible to see completely different fauna with just a short boat trip from the Asian landbridge to the Australian landbridge.  Yet, that narrow strip of ocean was enough to block back and forth colonization between the 2 continents.  Even most forest birds that could potentially fly the distance never did.  It was and is like 2 different worlds.

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I’ve spent the past month reading Alfred Wallace’s The Malay Archipelego.  He was a remarkable naturalist with amazing persistence and knowledge, able to discern the difference between thousands of species of insects and birds.  To collect new specimens, he took perilous boat journeys to islands located far from western “civilization,” and endured numerous hardships.  Many times his crew consisted of unreliable natives, but the malaria, sores, tormenting insects, and inconsistent food supply were reliable.  It seems like his sailboats were always going against contrary winds.  It’s hard to believe he was able to endure this for 8 years.

His values definitely differed from modern day sensibilities.  He was racist, believing Europeans were a superior race.  He assumed whenever he arrived on an island that he was entitled to get whatever he wanted. On one occasion he convinced the chief of a village to let him have temporary occupancy of a house, forcing the people who  lived there to move out.  (I must note that he did compensate the family with beads, knives, cloth, etc.) Then he wondered why the natives in that village were unfriendly to him.  Most natives in other locations were friendly.

The way he collected specimens would also disturb the modern naturalist.  He shot birds and mammals and stuck their carcasses in alcohol to preserve them.  Shooting beautiful birds simply to collect them for scientific knowledge was bad enough, but he also had no reservations about shooting orangutans.  To me, this is like shooting your neighbor so he can be displayed in a museum.  One time, he accidentally captured an orangutan baby after he killed its mother.  Though he noticed the baby ape behaved much like a human baby, it didn’t stop him from killing more orangutans.  He murdered 18 orangutans in all.  According to our modern values, this is just disgusting.  Some of the animals did get revenge on people then.  Wallace mentioned that tigers killed an average of 100 people a year in Singapore during the mid-19th century.  Today, there are no tigers anywhere close to Singapore.