Palm Groves and Coastal Savannahs of the Pleistocene

July 28, 2016

Western Gulf coastal prairies are subtropical grasslands that were formerly widespread along the coastal plains of Texas and Lousiana.  Bluestem and Indian grasses, common components of tall grass prairies to the north, also grow here.  Near the coast and on wetter locations the coastal prairies often merge with freshwater, brackish, and salt marshes.  Drier soils host cactus, mesquite, Texas persimmon, and prickly ash.  Hurricanes and lightning-induced fires maintain these prairies where herds of bison used to graze.  Groves of Texas palms (Sabal texana) occur in the lower Rio Grande valley because the river serves as a fire break that protects this non-fire adapted species.  Palm groves grew as far as 50 miles inland during the 19th century, but now there are only 100 acres left, most notably in the Sabal Palm Sanctuary located in Cameron County, Texas.  Coastal prairies have also become rare–less than 1% of these remaining unique grasslands are considered pristine.  Most have been converted to agriculture.

Western Gulf Coastal Grasslands map.svg

Location of coastal prairies.  This environment was likely more widespread during Ice Ages when dry land extended into the Gulf of Mexico for 50 miles.

A grove of Texas palms.  Paradoxically, this environment may have been more widespread during Ice Ages.

Coastal prairie adjacent to a salt marsh in the Aransas National Wildlife refuge.

Adults

Coastal prairies support 1 of the 2 remaining populations of whooping cranes.

Palm groves and coastal prairies were likely much more widespread during Ice Ages of the Pleistocene.  Glacial advance caused the Gulf of Mexico to recede, resulting in a larger region of dry land where both environments could expand.  The prairies served as a corridor that facilitated the movement of western and South American flora and fauna into southeastern North America.  Prairie chickens, upland sandpipers, and 13-lined ground squirrels are some western species that lived in the south during the Pleistocene.  Ground sloths, glyptodonts, pampatheres (a type of giant armadillo), and mixotoxodons (a large primitive ungulate) used the corridor to advance from South America to what today are the southern United States.  The coastal grasslands supported great herds of grazers including mammoths, bison, horse, and giant tortoises.  These in turn attracted large predators such as lions, scimitar-toothed cats, and dire wolves.

Paradoxically, this region may have been warmer during the coldest stages of Ice Ages.  Glacial meltwater periodically flushed into the North Atlantic, shutting down the Gulf Stream (the tropically heated water that flows into the North Atlantic and keeps climate mild).  This caused average annual temperatures in the upper and middle parts of North America to plummet.  So this tropically heated water stayed in the Gulf of Mexico, making average annual temperatures in this region warmer than modern day temperatures.  The geographical location of the transition between the colder region of the continent and the warmer region may have been abrupt, perhaps explaining why species with northern affinities are often found associated with warm climate species in so many Pleistocene-aged fossil sites.  This transition zone likely shifted frequently, on a decadal or even annual basis. Conversely, during interstadials when the Gulf Stream restarted, the middle latitudes enjoyed warmer average annual temperatures (but not as warm as those of today), while the region adjacent to the Gulf of Mexico cooled down (perhaps cooler than modern day temperatures). Changes in the composition of flora and fauna lagged behind these sudden climatic changes.

The lower Rio Grande valley is the northern limit of many tropical species found nowhere else in the United States.  Bird watchers can find red-crowned parrots, green parakeets, brown jays, green jays, chacalacas, groove-billed anis, Altamira orioles, Aplomado falcons, and common paroques here.  These tropical species likely spread across the region during stadials when the climate was warmer, but they experienced range reduction during interstadials.

parrot

Red-crowned parrots recently colonized south Texas.  Woodpecker-excavated cavities in frost-killed palms provide perfect nesting for them.

Green Jay Photo

Green jay.

Groove-billed anis.

Possible Resurrection of the Mammoth as early as 2018

July 22, 2016

The woolly mammoth (Mammuthus primigenius) will roam the earth again and soon, thanks to new advances in genetic engineering.  The new technology is based upon another fairly recent discovery known as CRISPR, an acronym that stands for clustered interspaced short palyndromic repeats.  Scientists discovered CRISPR when they were studying how a bacteria’s immune system works.  Viruses often attack bacteria.  To develop immunity to the viral infection, the bacteria cut and paste fragments of the virus’s DNA into its own genome.  Jennifer Douda and Emmanuelle Charpentier realized they could use this process to cut and paste desired changes into an organism’s genome.  They engineered the protein CAS9–2 RNA molecules that made it easy to cut and paste characteristics of 1 species into another species genome.  Feng Chang and Georgie Church were the first scientists to use this technology on a human cell, and now there is a big patent dispute between Chang and Douda over who deserves the monetary reward for this potentially lucrative invention.  As early as 2018, George Church of Harvard University plans to cut and paste certain characteristics of the woolly mammoth into an Asian elephant (Elephas maximus) embryo that will then be implanted in an elephant.  If this project is successful, the woolly mammoth will be reborn.

Scientists recently sequenced the genomes of 3 Asian elephants and 2 woolly mammoths.  (They were able to extract DNA from woolly mammoth carcasses preserved in Siberian permafrost.)  The Asian elephant is the closest living relative of the woolly mammoth.  The study confirmed the common ancestor of both species diverged about 5 million years ago.  The genetic evidence shows since that divergence the woolly mammoth evolved many adaptations to frigid environments.  Woolly mammoths evolved thick fur, short ears, a thick layer of fat, a hump of brown fat between the shoulders, reduced sensitivity to cold, enlarged sebaceous glands, and an altered circadian rhythm response.  Sebaceous glands secrete oil into hair for lubrication.  This made woolly mammoth fur waterproof and would have helped them keep warm in wet conditions.  The altered circadian rhythms were an adaptation to the extreme changes in day length that occur in the upper northern hemisphere.  These are the woolly mammoth characteristics Georgie Church will cut and past into an Asian elephant embryo.

Eventually, woolly mammoths could populate an experimental Pleistocene Park located in Siberia.  Herds of woolly mammoths could co-mingle with caribou, moose, horses, bison, yaks, Saiga antelope, and camels.  The foraging and trampling of all these animals compacts the soil, keeping the permafrost intact.  Scientists believe this could help mitigate the effects of global warming, so there is a practical purpose for re-introducing woolly mammoths to the environment.  I know it would be a tremendous tourist attraction and hopefully some day much of Siberia will be overrun with megafauna.

Pleistocene park photos

View of the experimental Pleistocene Park in Siberia.  The re-introduction of horses has increased the grassland cover here.

References:

Lynch, Vincent; et. al.

“Elephantid Genomes Reveal the Molecular Bases of Woolly Mammoth Adaptation to the Arctic”

Cell Reports 2015

Woolly Mammoth Revival

Specimen #USNM 437648

July 17, 2016

I was confused about the Harleyville Giant Cement Quarry fossil site for many years.  Some of the scientific literature reported the fossils found there were over 300,000 years old, while other papers gave them an approximate age of 20,000 years BP.  Finally, someone sent me a message, clearing up my confusion.  These are 2 different fossil sites–both in Dorchester County, South Carolina but several miles apart.  In 1989 Roy Ogilvie, an amateur fossil collector, found a nearly complete dire wolf skull at the site with the 20,000 year old bones.  This specimen is now stored at the U.S. National Museum and was given the number 437648.  It is the only dire wolf (Canis dirus) skull ever found in South Carolina, though several isolated teeth have been recovered from other sites.

010

Photo of specimen #USNM 437648 from the below referenced book.  It’s nearly complete, missing just a few teeth.

The size of this skull is remarkable.  Ronald Nowak, a renowned fossil canid expert, measured 62 dire wolf skulls that were excavated from the La brea Tar Pits in California.  #USNM 437648 is larger than all of them.  It may just be coincidence, but perhaps eastern dire wolves were on average larger than their western counterparts.  In any case this was a big wolf.  However, it is not the largest dire wolf skull known.  A dire wolf skull from south Texas and another from the Maricopa tar seeps in California were slightly larger than this specimen.

The associated faunal remains, known as the Ardis local fauna, suggest #USNM 437648 lived in a mostly wooded habitat with some grassy openings and aquatic habitats.  Tapir, white-tailed deer, stout-legged llama, long-nosed peccary, woodrat, beaver, gray squirrel, flying squirrel, jaguar, Florida spectacled bear, and Jefferson’s ground sloth all are (or were) denizens of woodlands or even deep forest.  Mastodon, beaver, and river otter indicate wetland habitat.  Bison, horse, mammoth, meadow vole, hog-nosed skunk, 13-lined ground squirrel, and pampathere show that grassland environments existed here as well.  Dire wolves were a generalist species.  Specimen #437648 likely hunted in all 3 habitats.

Reference:

Sanders, Albert

Additions to the Pleistocene Mammal Faunas of South Carolina, North Carolina, and Georgia

American Philosophical Society 2002

Extinct Subspecies of Pleistocene Jaguars (Panthera onca)

July 12, 2016

The ancestor of the jaguar diverged from ancestral lions and leopards about 8 million years ago.  An extinct species of jaguar (Panthera gombaszoegensis) roamed Eurasia from the early to mid Pleistocene (1.5 million years BP- ~300,000 BP).  This species crossed the Bering Land Bridge over 500,000 years ago and colonized North and South America where it evolved into Panthera onca–the same species still found today from Arizona to Argentina. The jaguar had a much wider range in North America during the late Pleistocene than it does now.  Jaguar bones, dating to this era, have been excavated from sites as far north as Washington state, Oregon, Indiana, West Virginia, and Pennsylvania.  I’ve reviewed the data from these sites in an attempt to determine when jaguars ranged this far north.  I was curious to know if jaguars were able to survive that far north during the coldest climatic phases.  However, these sites are all cave deposits without reliable dating evidence.  Associated faunal remains may be from specimens thousands of years older or younger than the jaguar remains and because climate often fluctuated rapidly during the Pleistocene, they can’t be used as an index for the climatic conditions that occurred when the jaguars lived in the regions.  The ancestor of Panthera onca did negotiate the Bering Land Bridge and Canada to reach its known Pleistocene range.  This region was quite cold even during warmer climate phases, so I believe Pleistocene jaguars were more adaptable to climatic extremes than one might expect.  There’s just not enough evidence to know for sure.

Posted Image

Both extinct subspecies of Pleistocene jaguars were somewhat larger than present day jaguars.

Pleistocene jaguars were abundant in southeastern North America, rivaling dire wolves (Canis dirus) as the most common large predator in the region then.  Jaguars have been unearthed from at least 18 sites in Florida, 6 sites in Tennessee, 2 sites in Georgia, 1 in South Carolina and another in Alabama.  A jaguar fell into Craighead Caverns in Tennessee and even left paw prints and claw marks in its failed attempt to escape the natural trap.  Complete skeletons of jaguars have been found in other Tennessee caves.  The jaguar that lived in the southeast during the Pleistocene was a distinct subspecies known as Panthera onca augusta.  It was given subspecies status based on its size, averaging 15%-20% larger than the modern jaguar.  Extant jaguars still demonstrate clines (geographical variations in size).  Present day jaguars average larger in the northern and southern limits of their range than they do near the equator.  Larger individuals maintain body heat more efficiently, perhaps explaining the size difference in the cooler parts of their range.  Present day jaguars also grow larger in areas where they can prey on livestock.  So it’s likely the combination of cooler climate and larger prey contributed to the larger size of P. onca augusta during the Pleistocene.

Another extinct subspecies of jaguar lived in South America–P. onca mesembrina.  This population of jaguars also averaged larger than present day jaguars.  A study of P. onca mesembrina genetics determined this clade became extinct in southern Argentina about 12,280 calendar years ago along with other regional megafauna including Darwin’s ground sloth, horse, a llama (Lama gracilis), and a local population of guanacos(Lama guanacoe).  These clades of jaguars and guanacos left no descendents, but other clades of these species recolonized southern Argentina less than 2,000 years later.  The scientists who participated in this study conclude human activities combined with a warming climate phase caused megafauna extinctions here.  Southern beech forests expanded as temperatures and precipitation increased, and the forest encroached on the grasslands.  Herds of grazing animals, forced to migrate greater distances to reach suitable pastures, were more easily ambushed by an increasing human population that now had access to more wild plant foods in the growing forests.  Megafauna survived previous climate changes by altering their patterns of movement throughout the landscape, but some how humans disrupted this during the terminal Pleistocene.

References:

Metcalf, Jessica; et. al.

“Synergistic Role of Climate Warming and Human Occupation in Patagonian Megafaunal Extinctions during the Last Deglaciation”

Science Advances June 2016

Simpson, G.G.

“Discovery of Jaguar Bones and Footprints in a Cave in Tennessee”

American Museum Novitates 1941

My 500th Post

July 10, 2016

I started this blog in March 2010 to promote my self-published book–Georgia Before People: Land of the Saber-tooths, Mastodons, Vampire Bats, and Other Strange Creatures.  I gradually began to enjoy researching and writing articles for this blog so much that I forgot all about promoting my book.  I try to keep this blog focused on the paleoecology of southeastern North America during the late Pleistocene.  However, scientists aren’t publishing research fast enough to keep up with my prolific output, so I often turn to topics barely relevant or even unrelated to my preferred subject.  To celebrate my 500th post, I went through all of my past articles and categorized most of them.  The categories can be found on the right hand side below the archives.  The categories include Pleistocene mammals, ornithology, herpetology, ichthyology, invertebrates, geology, anthropology, natural history expeditions, and standing on my soapbox.  The category of natural history expeditions are articles about my vacations.  I try to avoid politics on my blog but haven’t always succeeded.  Political articles are under the category of Standing on my Soapbox.

My blog averages 250-400 views per day, exceeding my expectations because the topic of Pleistocene paleoecology is fairly obscure.  I’m not sure if those views include many different people or a few people spending enough time reading my blog that they get counted more than once.  I’m afraid my numbers are probably inflated with spam machines.  Lately my most popular articles have been:

  1. https://markgelbart.wordpress.com/2012/12/10/bearzilla-the-biggest-bear-in-history/
  2. https://markgelbart.wordpress.com/2012/08/29/bull-sharks-carcharhius-leuceus-in-fresh-water-rivers/
  3. https://markgelbart.wordpress.com/2012/03/04/disjunct-populations-of-the-cottonmouth-water-moccasin-agkistrodus-piscivorus/
  4. https://markgelbart.wordpress.com/2014/03/14/looking-at-images-of-naked-women-naturally-increases-mens-testosterone-level/
  5. https://markgelbart.wordpress.com/2013/01/09/the-mysterious-nodoroc-site-in-winder-georgia/
  6. https://markgelbart.wordpress.com/2012/10/24/native-american-cannibalism-and-dog-eating/
  7. https://markgelbart.wordpress.com/2012/09/26/how-recently-did-the-jaguar-panthera-onca-roam-eastern-north-america/
  8. https://markgelbart.wordpress.com/2010/05/25/the-edisto-beach-fossil-site/
  9. https://markgelbart.wordpress.com/2014/08/01/astonishing-cougar-attacks-on-bison-bears-and-humans/
  10. https://markgelbart.wordpress.com/2010/07/08/cougars-vs-jaguars/
Thank to everyone who has taken the time to read, follow, or link my blog.
Cheers!

Pleistocene chickens (Gallus sp.)

July 4, 2016

Some of my wife’s relatives are chicken farmers.  Modern day poultry farmers raise chickens in long metal warehouses containing as many as 30,000 birds.  The warehouses smell like the inside of a toilet bowl that hasn’t been flushed or cleaned in a year.  Chicken farmers have to walk through each of their warehouses twice a day to collect and dispose of dead chicks.  This task prevents the spread of infectious diseases.  Agricultural catalogues sell Israeli gas masks for poultry farmers, so they won’t get sick from working inside their warehouses.  Wild chickens have a better quality of life than the birds that spend their entire lives inside these awful concentration camps.  At least they get to breathe fresh air and live naturally.

According to the paleobiology database, chickens formerly lived all across Eurasia.  The bones of extinct species of chickens have been unearthed at 8 sites in Europe.  These extinct species lived from the late Miocene to the early Pleistocene.  But when Ice Ages began occurring, the range of the chicken was reduced to southeast Asia.  Now, there are 4 or 5 species of chickens, but many additional species existed when earth’s overall climate was warmer.  Chickens require warm tropical/semi-tropical river valley forests where they can forage for seeds, fruits, and insects on the ground.  They can’t endure harsh temperatures.  Curiously, there are no known Pleistocene-aged fossils of chickens from their current range, though they undoubtedly abounded in the region then.  Bone preservation is uncommon in lowland tropical forests because of the acid soils.

Distribution map of the red jungle fowl, 1 of the ancestors of the domesticated chicken.

Research of the origin of chicken domestication is confused and contradictory.  Zooarchaeological and genetic evidence suggests chickens were first domesticated in northern China about 8,000 years ago.  However, some scientists re-examined the zooarchaeological evidence and determined the chicken bones were misidentified.  Instead, these supposed chicken remains are actually pheasant bones.  They also note that chickens are and were not native to northern China, a temperate zone region.  The fauna associated with the pheasant bones consisted of temperate species such as red deer, sika deer, and wild boar.  The species of mammals that co-occur with wild chickens including rhesus macaques, Asian elephants, and rhinos were absent from this region.  Northern China is just too cold for chickens, and it’s far more likely they were first domesticated in their native range of southern China.  By 3000 BP chicken farming had spread to northern China where the birds could survive winter with human help.

The modern farm-raised chicken is a hybrid cross between 2 species–the red jungle fowl (Gallus gallus) and the gray jungle fowl (G. sonneratii). Genetic evidence suggests the yellow skin pigment descends from the latter species.  Feral chickens occur locally in many towns and cities across southeastern North America including Miami, Key West, St. Augustine, Houston, New Orleans, and Fitzgerald, Georgia.  Chickens living in Fitzgerald descend from a population released along the Ocmulgee River.  The Georgia State Fish and Game Department hoped the birds would become a popular target for hunters.  Instead, the chickens abandoned the river bottomland forest and moved into suburban areas of the nearby town where they have thrived for decades.  Their preference for human-modified habitats may mirror their close ties to habitats modified by elephant foraging in their native range.  Elephants expand and maintain open areas, and they knock fruit to the ground.  Their manure attracts insects and contains undigested seeds.  Wild chickens benefit from the presence of elephants.  In suburbs humans maintain the open areas and accidentally provide food for chickens.

Feral chickens in Fitzgerald, Georgia.

Some people love suburban wild chickens, while others (the get-off-my-lawn assholes) resent the crowing and droppings.  I like free-ranging chickens better than grouchy old people.

References:

Eriksson, J; and et. al.

“Identification of the Yellow Skin Gene Reveals a Hybrid Origin of the Domestic Chicken”

PLOS Genetics 2008

Peter, Joris; and Ophelia Librasseum, Hai Deng, and Gregor Larsh

“Holocene Cultural History of Red Jungle Fowl (Gallus gallus) and its Domestic Descendent in East Asia”

Quaternary Science Reviews   June 2016

Before Cows were Cowed

June 28, 2016

One of the comments below a youtube video showing water buffalo (Syncerus caffer) defending a calf from lion predation expressed ridicule toward the big cats for being chased away by “a bunch of cows.”  The word, cow, used as a verb, descends from the Old Norse word, Kuga, meaning to oppress, intimidate, or easily herd; and the word, coward, originates from the Latin word, cauda, meaning tail or tail between the legs.  The origins of the 2 words might be interrelated, though the noun form of cow is likely a verbalization of the lowing sound cows make.  Modern cows were bred to be cowed, as in easily herded.  However, the ancestor of the cow, the aurochs, (Bos primigenius), was anything but easily herded.  They were larger and fiercer than modern cattle and readily attacked man on sight.  Nevertheless, they became extinct.  The last known aurochs was killed in Poland during 1627.  For propaganda reasons the Nazis bred primitive cattle in an attempt to bring the aurochs back, creating a breed known as the Heck.  Although the Heck never reached the size of the aurochs, some individuals are so aggressive that modern farmers find them impossible to raise.  Wild cattle are dangerous, and a more informed person would not ridicule lions trying not to get trampled and gored.

Prehistoric cave painting of an aurochs, the much larger and more aggressive ancestor of modern cattle.

Amazingly, humans somehow began to tame and breed the aurochs, probably about 8,000 years ago.  The early herdsmen selected individuals for smaller size, reduced aggression, easier herding, and better disease resistance.  Genetic evidence from a 6700 year old cow bone found in Derbyshire, England suggests the early domesticated cattle occasionally back bred with the aurochs.  Domestication of the aurochs took place in 2 different geographical regions.  Aurochs, tamed and bred in eastern Europe, are the ancestors of Bos taurus, and the Indian aurochs was bred into Bos indica.

Florida cracker cattle descend from cows brought to North America by the Spanish in the 1500s.

Bos indica.  They descend from a geographically separate population of aurochs than Bos taurus.

Texas longhorn cattle are Bos taurus x Bos indica hybrids.  Wild longhorns are tough animals capable of fighting off wolves, bears, and cougars.  Hundreds of thousands ranged Texas and Mexico from ~1700-~1900.

Early Spanish explorers and settlers brought cattle to North America during the 16th century.  They were let loose in the woods and fields to forage, and soon there were large herds of feral cattle wandering southeastern North America.  Wayne Van Horne critically reviewed all of the early accounts of bison in the region, and he determined most of these were probably referring to feral cattle rather than bison.  European colonists used the term, buffalo, interchangeably for either wild cattle or bison.  Most had never seen a bison, and there were no field guides that could’ve aided a correct identification.  Van Horne thinks the “buffalo” General Oglethorpe, the man who founded Georgia, hunted in 1746 were actually feral cattle.  The Great Buffalo Lick, located in central Georgia, may be misnamed because feral cattle were licking the soil there, not bison.  William Bartram saw great mixed herds of feral cattle, horses, and deer but never saw a buffalo when he traveled through the south from 1773-1776.  He did see bones of buffalo, but these could’ve been the bones of wild cattle.  However, Van Horne does note 3 credible accounts of bison in the deep south.  Mark Catesby correctly described bison ranging near Fort Moore along the border of central Georgia and South Carolina.  John Lawson reliably reported bison migrating through a mountain pass to the Cape Fear River in North Carolina.  And some early Spanish explorers saw bison feeding in abandoned Indian fields located on the panhandle of Florida.  The historical evidence suggests bison were very rare in the post-Pleistocene deep south, but the population of feral cattle here exploded during European colonization.  By the Civil War the cattle population of Florida was 700,000 vs. 140,000 people, and most of these herds were feral.

The longleaf pine savannahs that supported large herds of wild cattle in the deep south were also excellent habitat for sandhill cranes, Canadian geese, and turkeys.  Cattle grazing improves habitat for burrowing owls and caracaras.  Payne’s Prairie in central Florida is a remnant of habitat where bison, Florida cracker cattle, and a rich diversity of birdlife can still be found.  Some day, I hope to visit Payne’s Praire, but I can’t get other family members interested in it as a vacation destination.

References:

Park, Stephen; et. al.

“Genome Sequencing of the Extinct Eurasian Wild Aurochs, Bos primigenius, Illuminates the Phylogeography and Evolution of Cattle”

Genome Biology 2015

Van Horne, Wayne

“A Critical Assessment of Evidence Relating to the Range of the American Bison (Bison bison) in Georgia”

Early Georgia 40 (2) 2013

 

Trust the Coprolites, Not the Stable Isotope Analysis

June 24, 2016

Scientists analyze the bone chemistry of extinct species to determine what they ate.  This is known as “stable isotope analysis.” Some scientists even claim it’s possible to determine which carnivores outcompeted other large predators based on their stable isotope analysis.  (See:  https://markgelbart.wordpress.com/2015/05/02/surprising-discoveries-of-large-carnivore-dietary-preferences-on-the-pleistocene-mammoth-steppe/ )  I was always skeptical of the broad sweeping claims of these studies because the sample sizes were too small, they rely on too many assumptions, and they use too much dodgy math.  But I never voiced my skepticism.  I thought what do I know?  The authors of these studies are brilliant scientists, and I am just a lay-shmuck.  However, a new study vindicates my skepticism.  Oddly enough, this study was published in the comments section of Quaternary Science Reviews , rather than as a regular article, even though it is a scientific study and not an opinion piece.  The authors of this study examined the coprolites and gizzard contents of 3 different species of extinct moas that formerly ranged throughout New Zealand.  The moa coprolites were associated with the subfossil bones of the birds, so this gave scientists an opportunity to test the accuracy of stable isotope analysis.  They discovered the assumptions they make based on stable isotope analysis are not at all reliable.

Skeleton of the heavy-footed moa.

The environment of New Zealand before man arrived on the islands consisted of southern beech forest mixed with grassland.  The coprolites of the heavy-footed moa (Pachyornis elephantopus) show that if fed in the open grasslands.  The little brush moa (Anamalopteryx didiformis) ate plants the grow in the forest understory, and the giant moa (Dinornis robustus) was a generalist feeder that ate plants of the woods and grasslands.  The stable isotope analysis of the moa bones suggested the opposite–that the little brush and giant moas fed in more open environments than the heavy-footed moa.  The direct evidence shows stable isotope analysis is little more than wild guessing.  There is only 1 way to know for sure what extinct animals ate…the contents of their feces.

Mastodon dung excavated from the Aucilla River, Florida.  We know exactly what mastodons ate in Florida by identifying the contents of their feces.

Reference:

Rawlenee, Nicolas; Jamie Wood, Herve Bocherens, and Karyne Rojere

“Dietary Interpretations for Extinct Megafauna Using Coprolites, Intestinal Contents, and Stable Isotopes: Complimentary or Contradictory?”

Quaternary Science Reviews June 2016

Flooded Bat Caves of the Caribbean

June 21, 2016

Sea level rise following the end of the most recent Ice Age reduced the land area of the Caribbean Islands.  (See: https://markgelbart.wordpress.com/2011/11/11/banana-hole-fossil-sites/ )  The Bahamas, now consisting of numerous small islands, was formerly 1 big island.  During the Pleistocene the Caribbean Islands hosted an interesting, if depauperate, mammalian fauna including dwarf ground sloths, monkeys, rodents, insectivores, and bats.  The extinctions of dwarf ground sloths on Caribbean Islands occurred well after the extinctions of mainland ground sloths, and the timing is associated with the colonization of the islands by people. However, a recent study of bat extinctions and extirpations on Caribbean Islands suggested they were caused by rising sea levels that flooded cave roosts and reduced the area of suitable bat habitat.  But there was a big flaw in this study–the authors didn’t use radiocarbon dating of subfossil bat material.  A newer study remedied this flaw and determined Caribbean bat extirpations occurred thousands of years after sea level rose near present day levels.  The authors of this study focused on specimens of the 9 species of bats found in Ralph’s Cave on Abaco, the northernmost island of the Bahamas.

Location of Abaco, northernmost island of the Bahamas.  There are partially flooded caves underneath the surface of this island that serve as bat roosts.

Ralph's Cave, Abaco (Brian Kakuk) 15.5 : 4

Ralph’s Cave. Bats roost in the parts that are above water.

Of the 97 bat bones found in Ralph’s Cave, 51 of the specimens belong to species that still roost in the cavern, parts of which are still above water.  The extant species include the big brown bat (Eptesicus fucus), Bahamian funnel-eared bat (Chilonotulus tinisterferons), buffy flower bat (Erophylla segherum), and Waterhouse’s leaf-nosed bat (Macrotus waterhousii).  The bones of 5 species of bats that no longer inhabit Abaco were excavated from the cave as well.  These include specimens of the Greater Antillean long-tongued bat (Monophyllus redmani), Parnell’s mustache bat (Pteronotus parnelli), Cuban greater funnel-eared bat (Natalus primos), minor red bat (Lasiurus minor), and the southeastern myotis (Myotis austroriparius).  Radiocarbon dates of the minor red bat, Cuban greater funnel-eared bat, and Parnell’s mustache bat show these 3 species lived on Abaco as recently as 3600 BP.  The southeastern myotis, a widespread bat in southeastern North America, still inhabited Abaco 4000 years ago, and the Greater Antillean long-tongued bat occurred on the island until 1700 BP.  Radiocarbon dating of additional specimens of these locally extirpated bats may show they lived on Abaco even more recently.

Picture

The Greater Antillan Long-tongued bat eats nectar, fruit, and insects.  They’ve been extirpated from Abaco.

Pteronotus parnellii

Parnell’s mustache bat.  Also extirpated from Abaco.

The Cuban greater funnel-eared bat is extirpated from the Bahamas and is in danger of extinction in its last stronghold–Cuba.  The 1 cave where it still roosts recently collapsed.

The authors of this study also calculated the amount of suitable bat habitat on Abaco, and they determined “the minimum amount of bat habitat to sustain viable bat populations (of the extirpated species) was unchanged” following the transition from the Pleistocene to the Holocene.  Bat habitat shrank but not enough to cause these species to disappear.  The authors of this paper stated “the precise mechanism (of extirpation) is undetermined.”  They suggest human activities may have played a role.  Humans setting fires, clearing forests, or directly gathering the bats could have been detrimental to the extirpated species.  I don’t think humans preyed on these bats because they are too small.  Humans do eat flying foxes in Asia, but these fruit-eating bats are sizable and have substantial meat on their bones.  If humans are responsible for the extirpation of some bat species on Abaco, it must be through some form of habitat alteration.

References:

Centene, J. Angel; and David Steadman

“Fossils Reject Climate Change as the Cause of Extinctions of Caribbean Bats”

Scientific Reports 2015

Danalos, Lilliana; and Amy Russell

“Deglaciation Explains Bat Extinctions in the Caribbean”

Ecology and Evolution November 2012

 

 

Pleistocene Rabies

June 16, 2016

Viruses in the lyssavirus genus cause rabies, still a feared disease in many Third World countries.  Rabies kills over 24,000 people every year in less developed countries, but the annual death toll in the U.S. since 1900 has dropped from about 100 to 1 or 2.  Rabies viruses evolved characteristics that force physical reactions in infected organisms, and these reactions help facilitate the spread of the virus into the environment.  The rabies virus attacks the central nervous system of a vertebrate.  Eventually, the infection causes an inflammation of the brain.  Symptoms include insomnia, the inability to swallow, and a paralysis that inevitably leads to death.  An infected animal, unable to swallow, still produces saliva, and this spit foams at the mouth.  The saliva is loaded with the virus.  The insomnia causes great confusion and irritability, especially among carnivores that require lots of sleep.  (For example cats sleep 20 hours a day.)  This explains why animals infected with rabies behave oddly and more readily bite.  They become unknowing slaves to the virus, passing it in their infected saliva when they bite because they are behaving irrationally.

Studies of vampire bats determined rabies spreads in waves.  Some individual bats, unlike humans, are immune to the virus, and the population of immune individuals increases.  Rabies will disappear from the population for awhile but will return after a few generations when enough non-immune individuals are born.

Rabies viruses belong to the lyssavirus genus.

YouTube video of a raccoon infected with a rabies.  The virus attacks the brain in a way that makes the victim unable to swallow.  The virus then spreads in the foaming saliva on the mouth and is transmitted via a bite into the blood stream of another organism.  If you see an animal like this, shoot it, or call somebody else to come shoot it.

Louis Pasteur and Emile Roux invented the first rabies vaccine in 1885, and it has since been improved upon.  The widespread vaccination of pets accounts for the decline in human rabies in the U.S.  The vaccine can save people after they have been bitten by a rabid animal as well.  Modern treatment consists of thoroughly washing the wound with soap (this alone can kill the virus), followed by 5 injections in the shoulder with the vaccine.  Doctors no longer administer rabies shots deep into the stomach muscle.  Vaccinations only work if given before brain inflammation occurs.  Formerly, the mortality rate from rabies-caused brain inflammation was 100%.  But in 2004 Rodney Willoughby invented the Milwaukee Protocol.  His patient, Jeanna Giese, was suffering encephalitis after being bitten by a bat a month earlier.  (The girl and her mother didn’t realize the bite required urgent treatment.)  Dr. Willoughby hypothesized the rabies virus killed humans before the person’s own immune system had a chance to produce enough anti-bodies.  So he put Jeanna in a medically-induced coma using anesthetics and barbituates, and he also prescribed anti-viral medication.  Meanwhile, she was kept on a respirator.  After a week her body had become immune to the disease, and she survived, though she suffered some brain damage, and it took her months to learn how to walk again.  Since this case, the Milwaukee Protocol, named after the location of the hospital where it was first tried, has been used 41 times but has just an 8% survival rate, and the survivors have varying degrees of brain damage.  Do not delay treatment, if bitten by a wild animal.

ff_rabies4_f

Jeanna Giese is the first person to ever survive rabies after the disease had progressed to the brain inflammation stage.

Rabies is an ancient disease that was certainly widespread during the Pleistocene.  Rabies occurs on every continent except Antarctica and may predate the break-up of supercontinents.  Scientists don’t know where it originated.  Medical historians believe rabies occurred in the Americas before Columbus, along with other diseases such as syphilis, tularemia, giardia, dysentery, hepatitis, herpes, and staph infections.  The Spanish encountered rabies early during the conquest of South America.  It’s not likely they brought infected animals with them.  An animal infected with rabies would show symptoms before the long sea journey was over and would’ve been destroyed on board ship.

References:

Hu, W.T.; Rodney Willoughby and G.M Hoffman

“Long Term Follow Up after Treatment of Rabies by Induction of Coma”

New England Journal of Medicine 2007

Johnson, Nicholas; et. al.

“Vampire Bat Rabies: Ecology, Epidemiology, and Control”

Viruses May 2014

Martin, Debra and Alan Goodwin

“Health Conditions before Columbus: Paleopathology of North America”

Western Journal of Medicine

Vos, A; et. al.

“The Occurrence of Rabies in Pre-Columbia Central America: an historical search”

Epidemiology and Infection 39 (10) 2011

 


Follow

Get every new post delivered to your Inbox.

Join 112 other followers