* Astronomy

The lancelets (from "lancet"), also known as amphioxi, comprise some 22 species of fish-like marine chordates with a global distribution in shallow temperate and tropical seas, usually found half-buried in sand. They are the modern representatives of the subphylum Cephalochordata, formerly thought to be the sister group of the craniates.
Lancelets serve as an intriguing comparison point for tracing how vertebrates have evolved and adapted. Although lancelets split from vertebrates more than 520 million years ago, their genomes hold clues about evolution, particularly how vertebrates have employed old genes for new functions. They are regarded as similar to the archetypal vertebrate form.
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A "day", for a blind, cave-dwelling fish in Somalia, is twice as long as ours.

Most animals have an internal body clock, or circadian rhythm, that lasts around 24 hours and is modified by the light-dark cycle of a day.
But an international team, whose research is published in the open access journal PloS Biology, shows that certain blind cave fish have a circadian rhythm that lasts almost two days.
The cavefish, Phreatichthys andruzzii, has evolved for nearly two million years in the isolated darkness of caves beneath the Somalian desert.
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Deep in the Silurian seas, some 420 million years ago, a strange structure had just emerged in the bodies of many new vertebrates. Some fish began developing a defined upper and lower jaw that allowed them to devour large and hard-shelled organisms.
Today more than 99 percent of vertebrates have these handy eating apparati. But new research shows that for all of their utility, mandibles did not take over the oceans in one swift chomp, as many scientists had previously assumed. Rather, the early, jawed fish didn't make too much of a dent in their jawless compatriots' success for some 30 million years. The new findings were published online July 6 in Nature (Scientific American is part of Nature Publishing Group).
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Ky. man finds shark fossil in mine

A miner has found a fossil from a shark jawbone deep in a central Kentucky mine and now it is on display at the University of Kentucky.
The fossil was found in February in Webster County, Ky., where 25-year-old miner Jay Wright was working to bolt a roof 700 feet underground. The 300-million-year-old black jawbone is believed to be from a shark from the Edestus genus that once swam the seas over what is now Kentucky.
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