Friday, July 03, 2015

Single-Celled Predator Evolves Human-Like 'Eye'

Eye-like ocelloids are built from different endosymbiotically acquired components. 2015. Nature

A single-celled marine plankton evolved a miniature version of a multi-cellular eye so complex that it was originally mistaken for the eye of an animal that the plankton had eaten.
The eye-like structure contains a collection of sub-cellular organelles that look very much like the lens, cornea, iris and retina of multicellular eyes -- known as camera eyes -- that are found in humans and other larger animals.

Light micrograph (left), illustration (center) and transmission electron micrograph (right) show the eye-like structure in warnowiid dinoflagellates. PR

Thursday, July 02, 2015

Saber-Toothed Cat Canines Took Years To Grow

Using a Novel Absolute Ontogenetic Age Determination Technique to Calculate the Timing of Tooth Eruption in the Saber-Toothed Cat, Smilodon fatalis. 2015. PLoS One

The eruption rate of S. fatalis's permanent upper canines was 6 millimeters per month--double the growth rate of an African lion's teeth. But the extinct cat's dagger-like canines weren't fully developed until about three years of age. PR

Monday, June 29, 2015

Born This Day: Ray Harryhausen

Ray would have been 95 today.
Visit Ray's official site.

Died This Day: Thomas Huxley

From the UC Berkeley Page:

Huxley (May, 4, 1825 - June 29, 1895) was born in Ealing, near London, the seventh of eight children in a family that was none too affluent. At 21, Huxley signed on as assistant surgeon on the H.M.S. Rattlesnake, a Royal Navy frigate assigned to chart the seas around Australia and New Guinea. Huxley collected and studied marine invertebrates, in particular cnidarians, tunicates, and cephalopod mollusks. After leaving the Navy in 1854, Huxley managed to secure a lectureship at the School of Mines in London.

Huxley was a passionate defender of Darwin's theory -- so passionate that he has been called "Darwin's Bulldog" – and also a great biologist in his own right, who did original research in zoology and paleontology.

He is best known for his famous debate in June 1860, at the British Association meeting at Oxford. His opponent, Archbishop Samuel Wilberforce, was not-so-affectionately known as "Soapy Sam" for his renowned slipperiness in debate. During the debate, Archbishop Wilberforce ridiculed evolution and asked Huxley whether he was descended from an ape on his grandmother's side or his grandfather's. Accounts vary as to exactly what happened next, but according to one telling of the story, Huxley muttered "The Lord hath delivered him into my hands," and then rose to give a brilliant defense of Darwin's theory, concluding with the rejoinder, "I would rather be the offspring of two apes than be a man and afraid to face the truth."

All accounts agree that Huxley trounced Wilberforce in the debate, defending evolution as the best explanation yet advanced for species diversity.

However, Huxley did not blindly follow Darwin's theory, and critiqued it even as he was defending it. In particular, where Darwin had seen evolution and a slow, gradual, continuous process, Huxley thought that an evolving lineage might make rapid jumps, or saltations. As he wrote to Darwin just before publication of the Origin of Species, "You have loaded yourself with an unnecessary difficulty in adopting Natura non facit saltum [Nature does not make leaps] so unreservedly."

Huxley's most famous writing, published in 1863, is Evidence on Man's Place in Nature. This book, published only five years after Darwin's Origin of Species, was a comprehensive review of what was known at the time about primate and human paleontology and ethology. More than that, it was the first attempt to apply evolution explicitly to the human race. Huxley explicitly presented evidence for human evolution.

Huxley founded a remarkable dynasty of English scientists and thinkers. His son Leonard was a noted biographer and "man of letters." Leonard's oldest son Julian was one of the authors of the evolutionary synthesis of the early 20th century; Julian's son Francis became a noted anthropologist. Julian's brother Aldous Huxley was a novelist, screenwriter and essayist; his best-known book is the anti-utopia Brave New World.

Saturday, June 27, 2015

Friday, June 26, 2015

Hallucigenia’s Head

Hallucigenia’s head and the pharyngeal armature of early ecdysozoans. 2015. Nature

Illo by Danielle Dufualt

Abstract: The molecularly defined clade Ecdysozoa comprises the panarthropods (Euarthropoda, Onychophora and Tardigrada) and the cycloneuralian worms (Nematoda, Nematomorpha, Priapulida, Loricifera and Kinorhyncha). These disparate phyla are united by their means of moulting, but otherwise share few morphological characters—none of which has a meaningful fossilization potential. As such, the early evolutionary history of the group as a whole is largely uncharted.

Here we redescribe the 508-million-year-old stem-group onychophoran Hallucigenia sparsa from the mid-Cambrian Burgess Shale. We document an elongate head with a pair of simple eyes, a terminal buccal chamber containing a radial array of sclerotized elements, and a differentiated foregut that is lined with acicular teeth. The radial elements and pharyngeal teeth resemble the sclerotized circumoral elements and pharyngeal teeth expressed in tardigrades, stem-group euarthropods and cycloneuralian worms.

Phylogenetic results indicate that equivalent structures characterized the ancestral panarthropod and, seemingly, the ancestral ecdysozoan, demonstrating the deep homology of panarthropod and cycloneuralian mouthparts, and providing an anatomical synapomorphy for the ecdysozoan supergroup.

The topology shown denotes a newly retrieved ‘hallucishaniid’ clade—diagnosed by a swollen head, dorsal spines, and the differentiation of the anterior trunk and trunk appendages—includes luolishaniids, Orstenotubulus (not shown) and Carbotubulus within a paraphyletic ‘Hallucigenia’.

Tuesday, June 23, 2015

Died This Day: William Crawford Williamson - Father of Paleobotany

Williamson (Nov. 24, 1816-June 23, 1895) was an English naturalist who founded modern paleobotany. His father, John Williamson, was a Yorkshire geologist and the friend of William Smith, the father of English geology. Dr. Williamson's first paper (on organic remains in the Lias of Yorkshire) was published in 1834, when he was only 18.. In 1835 he was appointed curator of the Manchester Natural History Museum, a post which he held while pursuing his medical studies. His numerous earlier papers include one of the first memoirs on Foraminifera, a series of papers on the development of the scales and teeth of fishes.

Williamson was one of the oldest Fellows of the Royal Society, having been elected in 1854. He produced 19 memoirs on the "Organization of the Fossil Plants of the Coal-measures" between 1871 and 1893. He was appointed Professor of Natural History and Geology at Owens College, in 1851, and continued to hold the Chair of Botany until 1892. From here