Archive for April, 2022

When South Georgia was Deep Under Ocean Currents

April 27, 2022

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

April 20, 2022

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

Trichinella sp.

April 12, 2022

My late father was a physician fresh out of medical school when he encountered a patient with symptoms that baffled his more experienced colleagues. The patient suffered from fever, nausea, diarrhea, fatigue, muscle soreness, headache, stomachache, and eye swelling. None of the older doctors could diagnose his ailment, and the young teenager appeared to be on the verge of death. In desperation they consulted with my father, and he recognized the symptoms of trichinosis, a parasite infection caused by roundworms in the trichinella genus. At first the teenager denied eating undercooked pork, but then he admitted to tasting uncooked pork sausage. He was treated with life-saving anti-parasite medications. The boy’s father happened to be a gangster who worked for the mafia, and after this incident my dad liked to brag the mafia would get him anything he wanted in gratitude. My dad also liked to think his help influenced the boy not to follow in his father’s footsteps. Instead of becoming a gangster, he chose dentistry as his profession.

Lifecycle of a trichinella round worm parasite. Image from the CDC.
Image of trichinella cysts in human muscle tissue. From a medical encyclopedia.

Carnivores, humans, pigs, and rodents spread trichinella worms when they consume meat infested with roundworm cysts. Digestive juices in the small intestine activate the cysts, freeing the roundworms from encasement within the cyst. The parasites pierce the lining of the small intestine and enter the blood stream where they burrow into muscles, mate, and lay eggs that become cysts, waiting to get eaten. How sick an animal gets depends on how many cysts are ingested and how strong the animal’s immune system is. An ingestion of highly infested meat can be fatal because the trichinella worms will also burrow into heart, lungs, brain, and eye tissues. Doctors diagnose trichinosis by taking a muscle biopsy and exposing it to digestive juices. If roundworms are activated, the patient is considered to have trichinosis. Patients are treated with anti-parasite medications including mehendozole or albendozole.

Trichinella is supposedly absent from pork raised in the U.S. and western Europe because modern pigs are fed a clean grain-based diet and are kept in sanitary cages where they don’t have the opportunity to eat dead rats. This hasn’t always been the case. During the middle of the 20th century, trichinella was widespread among domesticated pigs. One study in 1947 of 5000 people found trichinella roundworms in 16.1% of the population. The infestation rate was particularly high in New York City during the 1930s because New Jersey pigs were fed restaurant garbage with trichinella-infested meat and rats. An average of 400 cases of trichinosis were diagnosed every year during the middle of the 20th century, and this figure is likely an undercount because trichinosis symptoms mimic flu symptoms. Many people with trichinosis probably thought they had the flu. As late as the 1960s, 2.2% of Americans had trichinella parasites in their bodies.

New cases of trichinosis in the U.S. average about 20 a year now, and these are from hunters who consume undercooked wild boar or bear. The CDC recommends cooking meat to an internal temperature of 180 degrees F to kill trichinella, though other sources say temperatures as low as 120 degrees F are adequate. Freezing meat at 5 degrees F for 10 days will kill Trichinella spiralis, but freezing does not kill other species of trichinella, and these species are more likely to be found in wild game.

I ate wild boar last week. Sprouts Market sells Durham Ranch products, and this company sources wild boar from Texas. I made wild boar papardelle–a dish reportedly popular in the Tuscan region of Italy. To make wild boar papardelle, marinate 1 lb of ground or finely chopped wild boar in 1 cup of Burgundy and 1 TBL of rosemary overnight. Put a carrot, onion, and chopped garlic in a food processor and grind them up. Remove the meat from the marinade and brown it in an electric skillet, while sautéing the chopped vegetables. Mix the vegetables with the meat and add the marinade and a 6 ounce can of tomato paste. Let this simmer, then add cooked egg noodles. In Tuscany parmesan cheese is not added, but my wife and daughter wanted it on their servings. The meat tastes of wine and tomato paste, and any meat would probably taste the same with this recipe.

Wild boar should be cooked thoroughly. Unlike pigs raised in modern sanitary conditions, wild boar can ingest trichinella parasites.
Wild boar papardelle is reportedly a popular dish in the Tuscany region of Italy. It’s easy to make.

Pleistocene Caracaras

April 6, 2022

The pasturelands interspersed with woodlots that cover much of rural south Florida today likely resemble the coastal oak and pine savannahs of this same region during the Pleistocene. South Florida and the southern Gulf Coast were climatically out of sync with the rest of North America during Ice Ages. When climate phases of dry cold conditions struck the rest of North America, south Florida and the southern Gulf Coast experienced warmer wetter subtropical climates. The Gulf Stream of the present day carries tropically heated water north, keeping climates in the northern latitudes of North America relatively moderate, but during cold climate phases of the Ice Age, it shut down. Instead, this warm water stayed at lower latitudes ironically making climate along the southern Gulf Coast even warmer than present day conditions. This warm climate spurred frequent thunderstorms and hurricanes. Lightning-ignited fires and windstorms destroyed trees and created open savannahs where mammoths, bison, and horses further suppressed the growth of unbroken forests. Trees that survived fire and wind were spaced far apart, and woodlots were restricted to the vicinity of waterholes where the trees were protected by watery fire breaks. This warm savannah habitat occurred from south Florida, Alabama, Mississippi, Louisiana, and Texas all the way to eastern Mexico. Much of this land has been inundated by sea level rise since the end of the last Ice Age. Warm coastal savannahs were ideal habitat for many species of plants and animals including caracaras.

Crested caracara. Photo by Wisniewski.
Crested caracara range map. There is a disjunct population in south Florida. During the Pleistocene this range was continuous with its population in Central and South America. Warm savannah occurred along the Gulf Coast, much of which is now inundated by rising sea levels.

Two species of caracaras inhabited Gulf Coast savannahs during the last Ice age–the crested caracara (Polyborus plancus) and the yellow-headed caracara (Milvago reidei). The former still occurs as a relict population in south Florida. This species lived on dry prairies throughout much of Florida, but that type of habitat has largely been transformed to rural, suburban, and urban landscapes. A recent scientific study in Florida found 103 crested caracara nests, and most of those were on improved pastureland. They seem to prefer pastureland over what remains of their original dry prairie habitat. I think this is a clue they benefit from the presence of megafauna. During the present day this means herds of cattle, but formerly they accompanied now extinct and extirpated megafauna. Caracaras forage on the ground for carrion. There was an abundance of carrion during the Pleistocene. They hunt for insects, reptiles, and small mammals stirred up by grazing herds of megafauna. And along with swallow-tailed kites and other opportunistic birds, they hunt down small animals fleeing wildfires. The widely spaced trees and small woodlots located on the pastures or savannahs are used for nesting.

Study of crested caracara nests in south Florida. Most of their nests are located on cow pastures that resemble Pleistocene habitat. Image from the below reference.
Yellow-headed caracara.
Yellow-headed caracara range map. During the Pleistocene they also occurred in Florida.

Fossil remains of both species were found at the Cutler Hammock site located in Miami, Florida. Yellow-headed caracaras no longer occur in North America, but habitat during some phases of Ice Age climate was so favorable in this region that it attracted both species. The Cutler Hammock site is notable for having yielded many remains of large carnivores including dire wolf, saber-tooth, giant lion, jaguar, and cougar. Their kills helped feed a diverse population of avian scavengers.

Reference:

Morrison Joan

“The Crested Caracara in the Changing Grasslands of Florida”

Click to access 3-17145_p.21115_Mor_FDPC_d.pdf

See also: https://markgelbart.wordpress.com/2013/10/18/two-pleistocene-carnivore-dens-near-miami-florida-part-2/