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

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

Map of the sites surveyed in the below referenced study.

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

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

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

Reference:

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

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

Quaternary Science Review 276 2022

Selected Plants from Jekyll Island

I encountered some interesting plants during my recent visit of Jekyll Island. Seaside oxeye (Borrichia frutescens) was a first for me, and I needed online help identifying it. This species grows in abundance on dry areas surrounding salt marshes, and it was in bloom on the island during mid-May, a little earlier than at other parts of the Atlantic coast. It belongs to the Aster family and can live for 5 years, spreading vegetatively and via seeds. The flowers attract butterflies. Leafhoppers and aphids feed upon the plant. Gall midges and gall wasps also attack the plant as part of their lifecycles. Birds eat the seeds. Seaside oxeye is reportedly an edible plant for humans and can be eaten cooked or raw, but it doesn’t have good flavor.

Seaside oxeye. This plant was blooming in abundance in the dry areas adjacent to salt marshes in mid-May on Jekyll Island.

Saltwater cordgrass (Spartina patens) is the dominant grass found in salt marshes along the North America south Atlantic coast. It is a keystone plant crucial to the health of this vital ecosystem. This plant helps maintain water quality and shelters many species of animals including diamondback terrapins, clapper rails, raccoons, otters, and fiddler crabs. Periwinkles graze on the grass to help keep it in check.

The dominant grass species growing in salt marshes along the southeastern Atlantic coast is Spartina patens. Note the dead trees. This spot is located just behind Driftwood Beach where saltwater intrusion is killing a maritime forest.

Saw palmetto (Serenoa repens) is the source of much quackery. Snake oil salesmen falsely claim extracts made from palmetto berries cure prostate problems. There is no scientific evidence for their phony claims. The palmetto berries are an edible fruit eaten by raccoons, bears, and Indians. Early European explorers were not impressed with the taste, however, and it was considered a desperation source of food. I’ve seen raccoon scat filled with palmetto berries. Saw palmetto is a scrub palm tree, and Indians used the palm fronds for fiber and roof thatching.

Saw palmetto next to a tree killed by salt water intrusion.

Live oaks here are being killed by saltwater intrusion here.

Common lantana (Lantana camara) was another first sighting for me. This species is native to Central and South America but has invaded warmer regions of North America, especially along the Atlantic coast. It is a member of the Verbena family, and its foliage is toxic to livestock. Lantana fruit, in particular the unripe berries, are highly toxic for humans, but birds relish them and spread the seeds in their droppings. This species is fire tolerant but shade intolerant and requires open landscapes to survive. The flowers come in 5 color varieties and attract butterflies and nectar feeding jumping spiders from the Salticidae family.

Lantana camara. This is a non-native species found on Jekyll Island.

Everglades Hammocks and Snails

During Pleistocene climate phases of high sea levels, the Everglades region of south Florida was flat sea bottom dotted with limestone outcrops and coral, and Lake Okeechobee was a saltwater bay. Today, the Everglades is a sea of sawgrass (Cladium jamaicense) dotted with hardwood hammocks that grow on top of the formerly inundated limestone outcrops and coral. Fresh water from Lake Okeechobee, funneled by a coastal ridge, flows south through the Everglades landscape. Sawgrass (technically a sedge not a grass) is a fire-adapted species, and during dry spells it burns, but hardwood hammocks are usually protected from the fires. Trees growing on the limestone-enriched elevated soils drop leaves, and the acidity from the decomposing leaf litter dissolves the limestone surrounding the hammock, creating moats filled with water that serve as fire breaks. Most hardwood hammocks also have an eroded solution hole in their middle, and they are elliptically shaped with 1 end pointed in the direction of the southward water flow.

Typical Everglades landscape–sawgrass wet prairie dotted with hardwood hammocks.

The composition of trees on Everglades hardwood hammocks includes a mix of tropical and temperate species. Tropical species are more common on southern Everglades hammocks, while temperate species predominate on the northern Everglades hammocks. The list of tree species found on these hammocks includes gumbo-limbo, mahogany, cocoplum, wax myrtle, live oak, red maple, hackberry, mulberry, Everglades palm, royal palm, and strangler fig.

Gumbo limbo tree. This is a tropical species common in hardwood hammocks of the southern Everglades. Everglades hardwood hammocks contain a mix of temperate and tropical species of plants.

Royal palms cannot survive frequent frost. Therefore, they are more common in the southern Everglades.

A diverse snail fauna thrives on Everglades hammocks because the limestone outcrops provide a rich source of calcium. Snails need calcium to develop their shells. The relatively frost-free climate also helps them breed year-round. Each hammock hosts a variation of tree snail (Liguus fasciatus) with a different color pattern. Over 58 variations are known. Tree snails feed upon fungus, lichen, and algae. 4 species of large apple snails live on these hammocks. 3 non-native apple snail species from South America are outcompeting the native species (Pomacea paludosa). Apple snails graze on green plant material and are a pest on south Florida vegetable farms. However, the rapidly expanding population of non-native apple snails benefit snail-eating bird species such as limpkins and the Everglades snail kite. The latter species is endangered, but the increase in snail populations has led to a rebound in Everglades kite numbers.

Native Florida apple snail. 3 species of non-native apple snails also thrive on Everglades hammocks.

Over 58 color variations of tree snails have been found on Everglades hammocks. Each hammock hosts a snail with a different color variation.

Limpkins primarily eat snails.

Endangered snail kites are increasing in population, thanks to rapidly spreading populations of non-native apple snails.

I’ve seen apple snails for sale in Asian food markets. I was not impressed with my lone snail-eating experience after I bought a can of imported escargot. They were relatively inexpensive, but they had no flavor at all. Escargots are traditionally served with butter and garlic sauce. I think eating snails is an excuse to dunk French bread in the butter and garlic sauce.

The Sand Tiger Shark (Carcharias taurus)–a Palaeocene Age Survivor

The sand tiger shark is the oldest still extant species of shark, having existed for at least 65 million years. Some sources claim it first evolved during the Cretaceous Age and lived with the dinosaurs 72 million years ago, but according to the scientific literature I can find, the oldest fossils of this species were found in the Cannonball Formation located in the Dakotas, a region that was formerly undersea, and species from fossil sites here date to the Palaeocene–the era immediately following the extinction of the dinosaurs. This is still impressive longevity for a species. By comparison modern man (Homo sapiens) has existed for about 200,000 years. The sand tiger shark should not be confused with the similarly named tiger shark (Galeocerde cuvier). Although sand tiger sharks occasionally bite people, they are not maneaters. Tiger sharks definitely are maneaters. The scientific name for sand tiger shark may also cause confusion. Carcharias taurus means bull shark in Latin, but the commonly named bull shark (Carcharhinus leucas) is also a different species.

Sand tiger shark, the oldest still extant shark species.

The sand tiger shark should not be confused with this species–the tiger shark. The former is not a maneater, but the latter is.

Sand tiger sharks can reach lengths of just over 10 feet long, and they feed upon fish, squid, and shrimp. They are known for preying on stingrays and smaller, slower sharks near the sea bottom at night. They rest during the day. They are the only species of shark to gulp air. This helps them retain buoyancy, so they don’t have to constantly swim like other kinds of sharks. The shark pups are born alive, the survivors of cannibalistic embryos attacking and eating each other while still inside their mother. Sand tiger sharks range in shallow coastal waters along the Atlantic coasts of North America and Europe. They also occur off the coasts of China, Japan, Australia, and South Africa. Scientists believe they were overfished to extinction in the Mediterranean Sea where they used to live.

Fossil sand tiger shark teeth.

Fossils from the Cannonball Formation. The majority of fossils from this site are sand tiger shark teeth. Image from the below reference.

Paleontologists found fossils of 22 species in the Cannonball Formation. This region was under ocean water until the end of the Palaeocene 55 million years ago. Sand tiger shark teeth are the most common fossil specimens found in this formation. Sand tiger sharks may be the oldest still extant species of shark, but the still extant Hexanus genus is even older. The Hexanus genus includes the gill sharks. Some species of extinct gill sharks lived 190 million years ago during the Jurassic.

Reference:

Cvancara, A.M.; and Hogansan, J.W.

“Vertebrates of the Cannonball Formation (Palaeocene) in North and South Dakota”

Journal of Vertebrate Paleontology 13 (1-23) 1993

Vacation 2022 Part 2–The Harris Neck National Wildlife Refuge

During World War II the U.S. government bought the land that currently makes up The Harris Neck National Wildlife Refuge. Before the Civil War most of this land belonged to a single wealthy plantation-owner, but in 1865 he deeded the land to one of his slaves. The land was later sold in parcels to white and black families who primarily worked in the seafood industry. An airfield was built on one of the parcels of this land during 1929 to serve as an emergency landing strip for flights between Jacksonville, Florida and Richmond, Virginia. The U.S. Army Air Force decided to purchase the airfield and all of the surrounding land during 1942, so the airfield could be used for aircraft that hunted for German submarines lurking off the coast. The U.S. government paid white landowners $37.21 per acre, while black owners were paid $26.90 per acre. I’m against reparations for slavery because it is too late. The time for slavery reparations was 100 years ago, but the victims of slavery and their immediate descendants are long gone. It also seems ridiculous to make modern taxpayers pay for the sins of some people’s great-great-great-great-grandfathers. However, I am in favor of reparations for African Americans who suffered discrimination by the federal government since the World War II era. The above-mentioned land purchase is one example. Many WWII era black veterans were denied GI benefits given to their white counterparts. The Agriculture Department routinely would not give loans to black farmers. Families that can show the federal government discriminated against them since the WWII era should be eligible for reparations. Many of these families and their immediate descendants are still alive.

Harris Neck Wildlife Refuge is located near Brunswick, Georgia, a coastal industrial town. I saw 14 species of birds here in less than an hour. (We didn’t stay long because the burning sun punished us, while biting horse flies dive-bombed our heads.) As soon as I parked my car, I spotted rare male and female painted buntings feeding at a bird feeder placed near the entrance. This alone made this side trip on the way home from Jekyll Island worth the time. I almost took a perfect photo of the colorful male, but it flew away as soon as my camera focused. I didn’t want to keep harassing the shy bird and left satisfied with my partially obscured photo.

Spanish moss-draped live oaks dominate the drier areas of The Harris Neck National Wildlife Refuge.

I saw these rare painted buntings as soon as I pulled into the parking lot. The male is the more colorful one. I almost took a photo of its entire body, but it flew away as soon as I had it in focus. I didn’t want to continuously harass it.

We walked to a couple of ponds, past the “don’t feed the alligator” signs, and saw great egrets, snowy egrets, cormorants, anhinga, and endangered wood storks. Who is stupid enough to feed an alligator?

I think this is an anhinga and not a cormorant because of the neck coloration.

This is a double-crested cormorant.

Endangered wood stork in flight.

Endangered wood storks.

This refuge is a mecca for ducks, geese, and bald eagles during winter, and during summer it serves as a rookery for egrets, herons, and storks. I was excited to realize when I got home that I’d taken a photo of a black-crowned night heron. I took the photo from a distance into the shade and wrongly assumed it was just another great blue heron. I have taken many photos of great blue herons. I can now add this species along with the painted bunting to my lifetime bird checklist. I had never seen either species before. In addition I saw red-headed woodpecker, red-bellied woodpecker, mourning dove, cardinal, tufted titmouse, black vulture, and a catbird.

Black-crowned night heron. This was the first time I had ever seen this species, and I didn’t realize I had gotten it on camera. I took this shot from a distance and assumed it was just another great blue heron.

Vacation 2022 Part 1–Jekyll Island

We were pleased with our room in the Days Inn at Jekyll Island. Many hotels claim to be handicapped friendly, but it seems as if they pay perfunctory attention to the needs of disabled people. However, this hotel really had excellent handicapped facilities, making my wife happy, thus reducing my stress, so I could enjoy the beach.

Driftwood Beach

An interesting active geological action is currently taking place on Jekyll Island. Engineers dredge the river outlet north of the island, and along with natural currents, this is causing the north end of the island to rapidly erode. The ocean is inundating a maritime forest here, killing the live oaks and cedar trees where they stand. This landscape is beautiful and different. Jekyll Island is not shrinking away. Longshore currents carry the eroded sediment from the north end of the island to the south end, and this end of the island is expanding in the form of large sand dunes.

The ocean is inundating the northern end of Jekyll Island, killing the maritime forest that stood here for centuries.

One can see how extensive a live oak’s root system is.

Bye bye forest, hello ocean.

Sediment from the north end of the island is carried by longshore currents to the south end of the island where it forms large sand dunes.

Sharktooth Beach

I’d rename this broken shell beach. Although I’m sure people find shark teeth here, they are greatly outnumbered by broken seashells. The beach appears to be composed of modern shells mixed with black-colored fossil specimens. It took us about 15-20 minutes to walk from the road to this beach located on Jekyll Creek between the island and the mainland. Many cedar trees covered in grapevines grew alongside the trail, and a salt marsh was also adjacent.

Sharktooth beach. We didn’t find any definitive shark’s teeth here.

Oyster shell, sea drill, and some other broken shells I found on Sharktooth Beach. The darker ones may be fossils.

The Sea Turtle Center

Veterinarians treat injured sea turtles here. Most are injured by human activities. It is worth the visit, but I felt sad the only opportunity to see these poor creatures is when they get hurt.

Loggerhead sea turtle being cared for at the Sea Turtle Center on Jekyll Island.

Juvenile loggerhead sea turtle.

Sinkey Boone, a shrimp trawler captain, invented the sea turtle excluder which are now required equipment on all shrimp trawlers. They let in shrimp but prevent turtles from getting caught in the nets and drowned. Sinkey seems like a bad name for a boat captain.

Diamondback terrapin juveniles. The Sea Turtle Center also cares for this species and injured box turtles as well.

Birds on Jekyll Island

I saw 19 species of birds on Jekyll Island plus gray squirrels, and the tracks of rabbit, deer, and raccoon on the beach.

Female boat-tailed grackle. This species is by far the most common songbird on the island. Males are larger and pure black.

Piping plover. This species spends summers in high northern latitudes. It still has a long way to go.

I think these are semi-palmated sandpipers.

I cannot identify what species of sandpiper this is. Closest match I can find is a sanderling. Somebody help.

This was part of a huge flock of brown pelicans.

Even Bugs Bunny likes to go to the beach. These are rabbit tracks.

My bird checklist for Jekyll Island includes boat-tailed grackle, red-winged blackbird, mourning dove, bluebird, cardinal, tufted titmouse, green heron, snowy egret, laughing gull, ringed gull, piping plover, semi-palmated sandpiper (I think), sanderling (I think), immature white ibis, common crow, fish crow, black vulture, black skimmer, and brown pelican. I also saw gray squirrels, a road-killed black racer, and the tracks of rabbit, raccoon, and deer.

2 Miocene-Aged Fossil Sites in Florida

The University of Florida Museum list 9 Miocene-aged fossil sites in Florida. By contrast there are no significant Miocene-aged fossil sites in Georgia. However, animals that lived in Florida also occurred in Georgia because the same habitats–subtropical forests and woodlands–prevailed over most of North America during the Miocene era, a period of stable warm climate. The Miocene lasted a long time from 25 million years BP-5 million years BP, but this division of time is an artificial human construct. Species that lived during the early Miocene were completely different, though often ancestral, to those that lived in the later Miocene. Therefore, I chose to examine the lists of Miocene species that occurred at 2 different sites with fossils separated in age by over 10 million years. Both sites are located northwest of Gainesville, Florida and are about an hour drive from the Georgia border. Certainly, these species lived in Georgia as well.

Fossils from the Thomas Farm site are estimated to be 18 million years old or early Miocene. The site was discovered in 1931 when Raeford Thomas dug a well into an ancient sinkhole. Clarence Simpson of the Florida Geological Society looked through the dirt dug up from the well-drilling and was the first to catalogue fossils at the site. The site has been studied off and on ever since, and scientists consider it the best North American Miocene-aged site east of the Mississippi. Paleontologists list 1 species of fish, 12 species of amphibians, 23 species of reptiles, over 27 species of birds, and 40 species of mammals from the fossil evidence left here. Most notable among the reptile fossils are an extinct boa constrictor (Boa barbouri), and an extinct alligator (Alligator olseni). Boa constrictors are now restricted to southwestern North America south to South America, but they were widespread across North America during the warmer Miocene. Olsen’s alligator was somewhat smaller than modern alligators. None of the bird fossils found here have been diagnosed to the species or even genus level. Scientists are unfamiliar with birds from this era, and they can only diagnose the specimens down to the family level. The most common large vertebrate fossils found here are from 3-toed horses and rhinos both of which dominate Miocene fossil assemblages. A common species of horse of this era was the 60-pound Archaeohippus blackbergi. Many of the specimens suggest high mortality caused by intraspecific fights between males who sported long canines. Thomas Farm is the only site where bones of an extinct camel known as Floridatriculus dolochiantereus have been found. Extinct species of pronghorns also left fossil evidence in the sinkhole. The top predator was White’s bear-dog (Amphicyon whitei). It was related to the common ancestor of bears and dogs, and it grew to the size of a grizzly bear.

This 60 pound 3-toed horse was a common species in early Miocene forests. 3-toed horses occupied an ecological niche filled by white-tailed deer today.

Bear-dogs were a top predator during the early Miocene. White’s bear-dog grew to the size of a grizzly. They were related to the common ancestors of bears and dogs.

Extinct species of pronghorns ranged throughout southeastern North America during the Miocene. Today, there is just 1 species restricted to short grass prairies in some western states.

Farmers plowing a peanut field discovered Miocene-aged fossils at the Tyner Farm site. This site was excavated between 2001-2005, and fossils from this site are estimated to be 7.5 million years old. Paleontologists list 4 species of amphibians, 6 species of reptiles including 2 kinds of giant tortoise and the remains of the modern species of alligator (A. mississippiensis), and 25 species of mammals. The site yields the oldest dated fossil remains of a tree squirrel in North America. Like the older dated Thomas Farm site, the fossil assemblage is dominated by 3-toed horses and rhinos, though they are different species than those found at the older site. Bones of 4 species of horse, 2 species of rhino, 2 species of pronghorn, 3 species of camels, 1 species of tapir, and 1 species of peccary were found here. 1 species of camel is particularly remarkable–Aepycamelos major. It was 13 feet tall, not counting its 6-foot-long neck, and it weighed over a ton. This species is a good example of convergent evolution. Like giraffes, it evolved great height and a long neck to feed upon leaves and twigs other vertebrate herbivores couldn’t reach, and scientists refer to them as giraffe-camels. Top predators included the Borophagine or bone-eating dogs, and the saber-toothed cat (Machaerodes catcopsis). The latter species was likely ancestral to the more famous late Pleistocene species of saber-tooth cats.

This is the hippo-like rhino. Along with 3-toed horses, rhinos were the most common large herbivores during the late Miocene. Rhinos became extinct in North America at the end of the Miocene when Ice Ages began.

The amazing giraffe-camels are a great example of convergent evolution. Despite not being closely related to giraffes, they evolved long necks to help them reach the leaves at the top of trees they could eat.

Pleistocene North America is often compared to modern day Africa in its faunal diversity. However, as I’ve noted in a previous blog entry (See: https://markgelbart.wordpress.com/2013/12/09/the-faunal-diversity-of-pleistocene-north-america-was-less-than-that-of-modern-day-africa/ ), modern Africa far exceeds Pleistocene North America in number of genera and species. Miocene North America makes a better comparison in diversity because a far greater number of animal species occurred on the continent during this era. Ice Ages began occurring at the beginning of the Pliocene about 5 million years ago. Seasonal climates including sub-freezing weather severely reduced the number of species that could live in North America.

Reference:

https://www.floridamuseum.ufl.edu/florida-vertebrate-fossils/sites/

A Lake and 2 Rivers in Florida that Vanish

The Native-American name for Lake Jackson, located near Tallahassee, Florida, is Lake Okeeheebee, meaning disappearing waters. Local authorities should have kept the original name because there is another Lake Jackson in central Florida, and there is also a Lake Jackson in nearby Georgia. The existence of multiple Lake Jacksons in this region made researching this blog article confusing. I wonder what Native-Americans thought the reason was for the periodic draining of this lake. They probably invented some kind of mythical story. Modern geologists know the cause for the periodic disappearance of this lake. The lake sits on karst terrain where sandy soils prevail. Karst terrain consists of unevenly eroding limestone. Slightly acidic rain causes bedrock to erode, resulting in many underground caverns that often collapse into sinkholes. There are 2 sinkholes underneath Lake Jackson–the Porthole Sink and the Lime Sink. During dry spells when the water table falls, water from Lake Jackson drains into these sinkholes, just like water draining from a bathtub. Plant debris and mud will temporarily block the sinkholes, but eventually most of the lake will drain with the exception of small pools here and there where fish populations survive. The permeable sandy soils allow water to refill the lake following periods of higher rainfall that cause the local water table to rise.

Map and location of Lake Jackson in north Florida. From Wikipedia.

Lake Jackson when it is full of water.

Aerial photograph of Lake Jackson after its water vanishes. Lake Jackson is surrounded by wet prairie. From the Tallahassee Democrat by Daniel Martinko.

Lake Jackson is 6.2 square miles and averages 6 feet deep when it is full of water, though it is as much as 28 feet deep over the sinkholes. The lake has drained 14 times over the past 200 years, and it is currently in a drained stage. Surprisingly, periodic drainages are good for fishing. The draining reduces populations of the non-native plant hydrilla, and the re-filling stirs up nutrients, increasing food for rebounding fish numbers. Fishermen claim the fishing for largemouth bass, crappie, bluegill and redear sunfish, and bullhead catfish is excellent. The latter species is especially well-adapted for surviving in small pools during drainage phases. Though not mentioned on the internet, I’m sure bowfin, gar, and non-native tilapia thrive as well. Birdwatchers report the presence of herons, egrets, limpkins, eagles, ospreys, ducks, geese, fish crows, and least terns. It’s good habitat for alligators, turtles, and frogs too.

The karst terrain makes it difficult for rivers to flow in this region, and there are 2 rivers that vanish here. The Alapaha River, a tributary of the Suwannee River, simply disappears into the ground, flowing right into a sinkhole, and it emerges miles away. The Santa Fe River also disappears into a sinkhole, also to emerge miles away. Both become subterranean during part of their course. A river flowing into the ground is known as a swallet.

Photo of the Alapaha River where it vanishes into the ground. It re-emerges miles away.

Image of where the Santa Fe River vanishes. From a youtube video by Adlai, JN.

Reference:

Bryan, J., Scott, T., Means, Guy

Roadside Geology of Florida

Mountain Press Publishing Company 2008

When South Georgia was Deep Under Ocean Currents

An Atlantic Ocean shoreline occurred at the present-day location of the Georgia fall line along an axis from Augusta to Macon to Columbus. Immediately offshore the ocean was shallow, but farther off the coast ocean currents were strong and flowed over a deep channel. This channel originated from a suture or fault where part of the African continent formerly connected to North America before the supercontinent of Pangaea rifted apart. Following sea level rise, ocean currents began flowing over this natural low area about 99 million years ago. Geologists refer to it as the Suwannee Strait during the first 60 million years of its existence and the Gulf Trough from the mid-Eocene to the mid-Miocene. Sea level changes caused the low channel to shift to the northwest, hence the name change. The swift current that flowed over it was part of the clockwise-moving Gulf Stream, an ocean circulation pattern found all the way up the North American east coast. To the south of the Suwannee Strait/Gulf Trough were shallower seas dotted with coral reef islands. During the Oligocene a large island, known as Orange Island, though no oranges grew there yet, emerged above sea level south of the trough. The Gulf Trough was deepest during the late Eocene about 35 million years ago, and geologists think parts of it were 600 feet underwater. During the Miocene sediment washed down from eroding Appalachian Mountains began to fill in the Gulf Trough. In its later years of existence, it was a slow-moving narrower estuary. About 15 million years ago sea level fell and the Gulf Trough existed for a while as an above ground canyon. Today, this canyon is buried deep underneath millions of years of sediment, but there are exposed outcrops where rivers erode through this ancient sediment. However, a relic is visible underwater in the Gulf of Mexico, and it is known as Desoto canyon.

From 99 million years ago to 15 million years ago South Georgia was under deep ocean currents. Geologists refer to this area as the Suwannee Straight and the Gulf Trough. It reached its largest depth about 35 million years ago. The Atlantic Ocean shoreline occurred along the present day fall line. South of this trough was a shallower sea dotted with coral atolls and islands that periodically rose and sank according to changing sea levels.

Swift ocean currents carried well oxygenated sea water that supported abundant aquatic life in the Suwannee Strait during the Cretaceous. Monstrous mosasaurs and pliosaurs preyed upon bony fish, some species themselves armed with fangs. Sea turtles and sharks swam over beds of an extinct group of clams known as rudists that came in many different shapes and sizes. Ammonites, extinct cephalopods related to squids and octopi, thrived in Cretaceous seas. Today, most foraminifera are small and measured in millimeters, but oddly enough there were 4-inch-long species of foraminifera living in the Suwannee Strait, though they are one-celled animals related to amoeba.

Rudist clams were abundant in the Suwannee Strait during the Cretaceous era. They came in many different shapes. They went extinct along with the dinosaurs at the end of the Cretaceous.

During the Eocene primitive whales evolved and made the Suwannee Strait their home. The Suwannee Strait and later the Gulf Trough was still rich in fish, mollusks, and other sea life. Fossils in the limestone and shale deposits of Cretaceous through Miocene Age in the region are commonly found wherever erosional processes expose them, and the limestone itself is made of many ancient seashells.

Primitive whales swam alongside dugongs, sharks, bony fish, and turtles in the Gulf Trough during the Eocene. A skeleton of this species was found in Burke County, Georgia.

Notable fossils of Oligocene Age from the Gulf Trough include dugong, nautilus, and rhodoliths. A nearly complete skeleton of a dugong was found in a northwest Florida fuller’s earth mine. Today, just 3 species of nautilus are extant, and these occur in the Pacific and Indian Oceans, but apparently, they were common during the Oligocene in the Gulf Trough. Aturia alabamensis, a 2-foot-long nautilus, likely scavenged or actively hunted crustaceans on the sea bottom. Rhodoliths still exist but were especially abundant in the Gulf Trough during the Oligocene. Rhodoliths are species of red algae that resemble coral and also produce calcium carbonate. Rhodolith fossils are part of large fossiliferous limestone outcrops found in southwest Georgia and are thought to have occurred on the shallower flanks of the Gulf Trough.

Aturia alabamensis. This was a species of nautilus that grew to 2 feet long and was common in the Gulf Trough during the Oligocene.

Rhodoliths, red algae that resembles coral, was abundant in the Gulf Trough during the Oligocene. They are still extant.

DeSoto Canyon off the Florida coast is the only remnant of the Gulf Trough that hasn’t filled with sediment.

John J. Audubon’s Trip Down the Ohio and Mississippi Rivers During 1820/1821

It’s hard to imagine how rich in wildlife the woods, fields, and streams of North America used to be. This is why I enjoy reading the journals of early explorers and settlers who described these forlorn scenes of nature. They saw more wildlife in a day than most modern people see in a year both in numbers and diversity. Audubon kept a journal of his trip down the Ohio and Mississippi Rivers, a journey that lasted from October 12, 1820 to January 7, 1821, and it is an extensive account, documenting the former abundance of wildlife in the region. Audubon had suffered business reversals when his once prosperous store went bankrupt, and he decided to travel to New Orleans where he could make money by drawing portraits of rich people and by giving art lessons. He was also working on an illustrated book of birds he hoped to sell in England. He left his family in Cincinnati, and he expected to be gone for 7 months. He traveled on a flat boat with an 18 year old young man, a boat captain, and a hunting dog named Dash that he alternatively referred to as “the bitch” or “the slut.”

J.J. Audubon and his dog. Although his name is attached to a modern conservation society, he killed as many birds as he could shoot.

Audubon and his young companion stopped to hunt every morning. Audubon carried a primitive shotgun known then as a fowling piece, and he shot just about every animal he saw. Unlike the organization that today uses his name, Audubon was not at all concerned about conservation. In his later years he did lament the reduction in game populations, but then he’d kill as many birds as he could shoot. A typical day of his journey was the first when he and his companion killed 30 “partridges” (probably quail), 27 squirrels, 1 woodcock, 1 barn owl, and 1 turkey vulture. After the morning hunt, he would draw 1 of the dead birds as the boat drifted downstream. Then he would pluck and clean the bird and throw it on the embers of the fire for his supper. Grebes were fishy, but he pronounced red-breasted thrushes (robins) to be fat and delicious. Birds that are now extinct were common during the early 19th century. Audubon often saw ivory-billed woodpeckers, and he stated they were more abundant along some parts of the river than pileated woodpeckers and flickers. He once shot 10 Carolina parakeets and fed them to his dog to see if they were poisonous. This seems strange, but Audubon often engaged in sadistic “scientific” experiments. He wrongly came to the conclusion parakeets were not poisonous when his dog didn’t get sick. He didn’t know the flesh of parakeets only became poisonous after they ate certain species of toxic plants. Audubon also wrongly thought immature bald eagles were a different species of eagle, and in another sadistic experiment he once nailed the foot of an eagle to the bottom of the boat, so he could draw it while it was alive. He claimed bald eagles were a new species and named it the bird of Washington after the first President.

Alexander’s painting of a bald eagle (top) and Audubon’s painting of a bald eagle (below). Some think Audubon simply plagiarized Alexander’s painting and falsely claimed his was based on a freshly killed eagle.

Species of birds still extant today were much more abundant and widespread during Audubon’s time. He saw a flock of 100 white pelicans on a sandbar in the Ohio River. White pelicans are not often seen on the Ohio River today. He also saw enormous flocks of thousands of ducks, geese, and blackbirds. Swans, herons, and sandhill cranes were a common sight. In addition to daily hunting, Audubon always set a line out for fish. On 1 occasion he caught a 64-pound catfish, likely a blue catfish–a new species for him. I’m sure the offal from all the birds he killed made excellent catfish bait. Big flocks of sea gulls followed the boat and fed upon the dead bird and fish parts he threw overboard. Once, his hunting led to fish and bird…he shot a merganser with a 9-inch-long sucker fish in its throat. Nearly extinct habitats were abundant then as well. They floated down parts of the river bordered by many miles of bamboo cane tangled with smilax vines. Canebrakes are very rare today.

Audubon saw a flock of 100 white pelicans on a sandbar in the Ohio River. According to range maps, this species no longer regularly occurs on the Ohio River.

Audubon reached New Orleans on January 7th. Gulls, fish crows, and robins were the most common winter birds here. Later in the season, the robins left, but tree swallows arrived to become 1 of the most common birds around the city. On his 2nd day in New Orleans, someone picked his pocket, but he was almost broke anyway. He made his living painting people’s portraits and giving art lessons. A notable incident while he was living in New Orleans was when he witnessed local hunters destroy a flock of 144,000 migrating golden plovers. Eventually, Audubon got a job tutoring the daughter of a rich plantation owner. (Audubon was unapologetically pro-slavery.) He taught her art, dancing, and math for $60 a month plus room and board. The plantation was located on Bayou Sara, and Audubon hunted daily in a nearby cypress swamp where he frequently saw prothonotary warblers, yellow-throated warblers, water thrushes, Mississippi kites, ivory-billed woodpeckers, and alligators. The women in the household where he tutored gradually cooled to him, and he quit. I wonder if they were expecting more romance from the married tutor. The lady of the house didn’t want to pay him, but the man did anyway. The private journal ends when Audubon returns to New Orleans, following his tutoring gig. Years later, Audubon did become successful selling his illustrated books about North American birds and mammals.

References:

Audubon, J.J.

Audubon: Writings and Drawings

Literary Classics 1999

Halley, M.

“Audubon’s Bird of Washington: Unravelling the Fraud that Launched The Birds of America“

Bulletin of the British Ornithologists Club 110-141 2020