Daily Archives: 7 September 2014

September 7, 1707 (a Wednesday)

Georges-Louis Leclerc, count de Buffon

On this date, the naturalist Georges-Louis Leclerc, count de Buffon was born in Montbard, France. Buffon is best remembered for his great work Histoire naturelle, générale et particulière(1749-1778: in 36 volumes, 8 additional volumes published after his death by Lacépède). It included everything known about the natural world up until that time and was translated into many different languages, making him the most widely read scientific author of the day, equaling Rousseau and Voltaire. Buffon’s views influenced the next two generations of naturalists, including Jean-Baptiste Lamarck and Charles Darwin.

Buffon was one of the first philosophers to grapple with the questions of evolution, both of Earth and of living creatures. At the time, church doctrine insisted that Earth was only six thousand years old and that each type of creature had been made independently by a Creator. He proposed instead around 1778 that the Earth was hot at its creation and, from the rate of cooling, calculated its age to be 75,000 years, with life emerging some 40,000 years ago.

Buffon noted that despite similar environments, different regions of the world have distinct plants and animals, a concept later known as Buffon’s Law, widely considered the first principle of biogeography. He made the radical conclusion that species must have both “improved” and “degenerated” (evolved) after dispersing away from a center of creation. He also asserted that climate change must have facilitated the worldwide spread of species from their center of origin. Buffon also proposed, in sharp contrast to his contemporary Carolus Linnaeus, that species are defined not by simple similarity of appearance but by reproductive fertility over time.

Advertisements

September 7, 1829 (a Monday)

Lithograph of dino fossils, Leidy (1860)

On this date, the American geologist Ferdinand Vandiveer Hayden was born. It is generally accepted that the first discovery of dinosaur remains in North America was made in 1854 by Hayden during his exploration of the upper Missouri River. At that time, the area was the hunting ground of the Lakota, Blackfeet, Atsina, and River Crow Indians. A lone white man in Indian Country was often fair game to the tribes, but Hayden’s passion for rocks and fossils earned him the name “He Who Picks Up Stones While Running” and a reputation for madness. The Indians left him alone.

Hayden explored what would later become known as the Judith River Formation, a large area of sedimentary materials deposited in the lowland areas bordering the Colorado Sea during the Late Cretaceous Period 78 to 74 million years ago. Here, Hayden’s party recovered a small collection of teeth which were later described (in 1856) by Joseph Leidy at the Academy of Natural Sciences in Philadelphia. Three of the specimens described were dinosaurs – Trachodon, Troodon (now known as Stegosaurus), and Deinodon (notice the use of ‘don’ meaning ‘tooth’). This was the first published description of dinosaur remains in the United States. Leidy recognised that Trachodon was a creature similar to Iguanodon.

Interestingly, for centuries the Blackfeet have inhabited the high plains of Montana and Alberta – the same area in which the dinosaur-rich, Late Cretaceous Hell Creek and Oldman Formations occur. Dinosaur fossils were known to the Blackfeet, who considered them to be the remains of giant, ancestral buffalo. The Blackfeet used dinosaur bones in rituals intended to insure good hunting. Notwithstanding the religious significance dinosaur bones had for the Blackfeet, they were quite enlightened in their view toward dinosaurs. They hit on the antiquity, and the organic nature of dinosaur remains, and in comparing them to buffalo showed their sophisticated knowledge of vertebrate anatomy. Referring to dinosaurs as large buffalo was thus good scientific practice in the context of their perception of the natural world. In doing this, they were as close to the truth as was the Rev. Dr. Plot back in England, or any other European of the time.

September 7, 1936 (a Monday)

Benjamin, the last known Thylacine (1933)

On this date, the last known Thylacine, commonly known as the Tasmanian Tiger or Tasmanian Wolf, died in captivity at Hobart Zoo, Tasmania, as a result of neglect. The animal, named Benjamin, was locked out of its sheltered sleeping quarters and exposed to freezing temperatures at night.

The Thylacine was the largest known carnivorous marsupial mammal of modern times. Like the tigers and wolves of the Northern Hemisphere, the Thylacine was an apex predator. As a marsupial, it was not closely related to these placental mammals, but because of convergent evolution it displayed the same general form and adaptations. Its closest living relative is thought to have been either the Tasmanian Devil or Numbat. Interestingly, the Thylacine was one of only two marsupials to have a pouch in both sexes (the other being the Water Opossum). The male Thylacine had a pouch that acted as a protective sheath, protecting the male’s external reproductive organs while running through thick brush.

Thylacinus in Washington D.C. National Zoo, c. 1906.

Virtually wiped out in the wild due to constant hunting (they were thought to be a threat to sheep and other small farm animals) and the encroachment of humans on their already limited habitat, the Thylacine was finally recognized as being in danger of becoming extinct in 1936, but much too late. There have been no confirmed sightings in over 70 years.  It was the last extant member of its genus, Thylacinus, although several related species have been found in the fossil record dating back to the early Miocene.