Tuesday, February 24, 2015

Monday, February 23, 2015

Animals Tend to Evolve Toward Larger Size Over Time

Cope’s rule in the evolution of marine animals. 2015. Heim, N.A., et al. Science.

The study reveals that over the past 542 million years, the mean sized of marine animals has increased 150-fold.
The research also found that the increase in body size that has occurred since animals first appeared in the fossil record around 550 million years ago is not due to all animal lineages steadily growing bigger, but rather to the diversification of groups of organisms that were already larger than other groups early in the history of animal evolution.

"That's also something we didn't know before," Payne said. "For reasons that we don't completely understand, the classes with large body size appear to be the ones that over time have become differentially more diverse."

Cope's rule was formulated in the late 19th century after paleontologists noticed that the body sizes of terrestrial mammals such as horses generally increased over time.
To test whether Cope's rule applies to marine animals as a whole, Payne and a team that included undergraduates and high school interns compiled a dataset including more than 17,000 groups, or genera, of marine animals spanning five major phyla-Arthropods, Brachiopods, Chordates, Echinoderms, and Mollusks-and the past 542 million years.

"Our study is the most comprehensive test of Cope's rule ever conducted," Heim said. "Nearly 75 percent of all of marine genera in the fossil record and nearly 60 percent of all the animal genera that ever lived are included in our dataset." PR

The Milky Way Over The Arizona Toadstools

From Astronomy Picture of The Day

Wednesday, February 04, 2015

Born This Day: Raymond Dart


Dart (Feb. 4 1893 - Nov. 22, 1988) was an Australian-born, South African physical anthropologist. In 1924, working with students in the Taung limestone South Africa, they discovered the first Australopithecus africanus. Dubbed "missing link" at the time, skull is also known as the 'Taung child', and was only three years old at the time of death. More on Dart here

Tuesday, February 03, 2015

Born This Day: Gideon Mantell

Mantell (Feb. 3, 1790 – Nov. 10, 1852), a physician of Lewes in Sussex in southern England, had for years been collecting fossils in the sandstone of Tilgate forest, and he had discovered bones belonging to three extinct species: a giant crocodile, a plesiosaur, and Buckland's Megalosaurus. But in 1822 he found several teeth that "possessed characters so remarkable" that they had to have come from a fourth and distinct species of Saurian. After consulting numerous experts, Mantell finally recognized that the teeth bore an uncanny resemblance to the teeth of the living iguana, except that they were twenty times larger.
In this paper, the second published description of a dinosaur, he concluded that he had found the teeth of a giant lizard, which he named Iguanodon, or "Iguana-tooth."

Mantell illustrated his announcement with a single lithographed plate. Mantell included at the bottom of the plate a drawing of a recent iguana jaw, which is shown four times natural size, and for further comparison, he added views of the inner and outer surface of a single iguana tooth, "greatly magnified."

The traditional story that Mantell's wife found the first teeth in 1822, while the doctor was visiting a patient, appears, alas, to be unfounded.

Info and plate from HERE.

Died This Day: Ernst Mayr


Any student of biology, or anyone with an interest in the natural world, will be familiar with Ernst Mayr who passed away on February 3rd, 2005 in Bedford, Mass. Born in Kempton, Germany he joined the American Museum of Natural History as a curator in 1931. In 1953 he left the museum to work at Harvard University where he stayed until his retirement in 1975.

While working on the problem of speciation in the birds of New Guinea, Mayr realized that the multitude of species and and subspecies that he saw could best be explained as being a snapshot of evolution in action. He suggested that new species could arise when the range of one species was fractured long enough for members in different parts of the range to evolve characters that would not allow individuals to reproduce when they were brought back together again. This lead to him developing the “biological species concept” in which species are defined as populations of interbreeding organisms rather than just a collection of characters. This idea, along with his theory of “allopatric speciation” was published in his book “Systematics and the Origin of the Species” (1942) and later contributed to the “Punctuated Equilibrium” theory of Niles Eldredge and Stephen Jay Gould.

Ernst Mayr was himself inspired by the work of geneticist Theodosius Dobzhansky on the fruit fly Drosophila melanogaster and his book “Genetics and the Origin of the Species” (1937). These two men, together with the paleontologist George Gaylord Simpson, combined the sciences of genetics, zoology and paleontology into what is now known as “the new synthesis” that provides the modern experimental underpinning to the concepts that Charles Darwin presented in his book, “On the Origin of the Species” .

For anyone interested in learning more about modern evolutionary theory I’d recommend Mayr’s recent book “What Evolution Is” (2002). It’s written in an engaging and readable format from the perspective of someone who’s thought about evolution all his life.

Tuesday, January 27, 2015

Died This Day: Adam Sedgwick

Adam Sedgwich (March 22, 1785 - January 27, 1873) was an English geologist who first applied the name Cambrian to the geologic period of time, now dated at 570 to 505 million years ago. In 1818 he became Woodwardian Professor of Geology at Cambridge, holding a chair that had been endowed ninety years before by the natural historian John Woodward.

He lacked formal training in geology, but he quickly became an active researcher in geology and paleontology. Many years after Sedgwick's death, the geological museum at Cambridge was renamed the Sedgwick Museum of Geology in his honor. The museum is now part of the Department of Earth Sciences at Cambridge University. From Today In Science History.

Monday, January 26, 2015

Born This Day: Roya Chapman Andrews


Photo from Parade of Life Through The Ages, by Charles Knight, Nat. Geo., Feb. 1942.

From the American Museum of Natural History web site:

Adventurer, administrator, and Museum promoterAndrews (Jan. 26, 1884 – March 11, 1960) spent his entire career at the American Museum of Natural History, where he rose through the ranks from departmental assistant, to expedition organizer, to Museum director.

He became world famous as leader of the Central Asiatic Expeditions, a series of expeditions to Mongolia that collected, among other things, dinosaur eggs. Although on these expeditions, Andrews himself found few fossils, and during his career he was not known as an influential scientist, he instead filled the role of promoter, creating immense excitement and successfully advancing the research and exhibition goals of the museum.

Learn about the Roy Chapman Andrews Society HERE.

Saturday, January 24, 2015

Premiered This Day (1956): The Animal World

“2 Billion Years in the Making!”

Produced and directed by Irwin Allen, whose long career included such TV hits as Lost In Space and Voyage To The Bottom Of The Sea, and movies like The Poseidon Adventure and The Towering Inferno.

The Animal World was one of the first films to present dinosaurs in the quasi-nature documentary so beloved by the Discovery Channel today. Rarely seen now, it featured about 10 minutes of great dinosaur stop-animation by Ray Harryhausen with Willis O’Brien. The entire sequence was released as an extra on the 2003 DVD release of The Black Scorpion.