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Six New Rattlesnakes Discovered

There are more species of rattlesnakes slithering around the U.S. than previously thought.

Six new species of western U.S. rattlesnakes have just been identified, according to a paper released this week.

Animal experts previously puzzled over the newly named rattlers, but did not then realize that the snakes represented unique species.

First Snake Crawled on Four Feet: Photos

"These snakes have been long been recognized by herpetologists as being demonstrably different, and in fact were designated as western rattlesnake subspecies in the first half of the 20th century," co-author Michael Douglas, a professor of biological sciences at the University of Arkansas, said in a press release.

He and co-author Marlis Douglas collaborated with Mark Davis, a research scientist at the Illinois Natural History Survey, and with Michael Collyer of Western Kentucky University. Their findings are published in the journal PLOS ONE.

As part of his doctoral research, Davis had previously collected data from nearly 3,000 western rattlesnakes available in natural history museums across the western U.S.

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Analysis of the snakes' DNA and head shapes enabled the researchers to identify the different rattlesnakes. The six new ones are as follows:

Crotalus viridis Crotalus oreganus Crotalus cerberus Crotalus helleri Crotalus concolor Crotalus lutosus "Crotalus" comes from the Greek word krotalon, which means "rattle" or "castanet." All such snakes are venomous pit vipers.

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Often when new species are discovered, they are declared to be highly endangered, helping to explain why they were not found earlier. That does not seem to be the case in this instance, though.

Michael Douglas said of the rattlesnakes, "None are currently considered rare, but species designation allows them to gain certain legal protection, particularly within individual states."

The newly identified rattlesnakes are expected to go into the animal record book after their scientific and standard English names are submitted to the International Commission on Zoological Nomenclature.

Great basin rattlesnake.

The world's first known snake has just been discovered in Brazil, according to new research that solves many mysteries about the slithering reptiles. The snake (

Tetrapodophis amplectus

), described in the latest issue of the journal Science, is also the first known snake to have four limbs. This strongly suggests that snakes evolved from terrestrial lizards, and not from water-dwelling species, as had been thought before. "The marine hypothesis is dead," senior author Nicholas Longrich of the University of Bath told Discovery News. "It's actually been pretty dead for a while now, but this is really pounding the nails in the coffin. Aquatic snakes evolved from terrestrial snakes -- many, many times." As this image shows,

Tetrapodophis

aka "Four Feet" was a meat-eating predator. It lived in what is now the Crato Formation of Ceará, Brazil, between 146 and 100 million years ago.

What the First Snake Looked Like

If Four Feet could be brought back to life today, "You would be confused, because you would be thinking that this looks like a snake...but it's odd; it shouldn't have feet," lead author David Martill of the University of Portsmouth told Discovery News. He, Longrich, and co-author Helmut Tischlinger believe that the unusual reptile and its kin evolved ever-smaller limbs after their predecessors went through a subterranean phase. During this period of the Early Cretaceous, the animals burrowed underground. "Limbs get in the way if you are burrowing through soft sand," Martill explained. "Much better to 'swim' through leaf litter or sand. As legs got smaller, 'swimming' became more efficient." The scientists further suspect that these undulating movements were pre-adaptations to actual swimming in water.

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Four Feet's front limbs were so small that Martill described them as being "pathetic" and "little." While miniscule, the feet seemed to be specialized, as they were broader than those of lizards. As a result, the researchers think the feet helped the snake to seize prey and clasp onto a partner when mating.

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Four Feet's head was slightly pointed and slender, suggests its skull. As for its overall appearance, "It looked, well, snaky," Longrich said. "It had the long, slender, serpentine body; it would have had a forked tongue," he continued. "It had the broad belly scales of a snake. This is unique to snakes, and amazingly the fossil actually preserves them." The individual died while young and was only about 8 inches long. The scientists are not sure how big members of the species would have become as adults, but they suspect that adults grew to be over 3 feet long.

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The remains of an unknown animal -- possible a lizard -- are remarkably preserved in the gut of the fossilized snake. Based on Four Feet's build, it probably bit its victims and then squeezed them, cutting off their circulation. Organ failure probably followed and then death. The gut contents also indicate that the snake had a feeding strategy similar to today's boa constrictors "in which proportionately large prey are ingested whole," the authors wrote.

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The serpentine fossil for Four Feet is extremely well preserved in limestone. It is in such good condition that "soft tissues are also preserved," according to the authors. The snake would have lived in an ecosystem with dinosaurs, they indicated. While this juvenile snake might have eaten small dinosaur eggs, it is possible that adults of the species "could take a hatchling dinosaur," Martill said. Longrich added that 40-50 million years after this snake's lifetime, there were large boa and python-sized snakes that definitely were regular consumers of dinosaur eggs. Remains of snakes are even found in dinosaur nests as a result. Poisonous snakes were not around then, though. They did not become widespread until about 34 million years ago, which was long after non-bird dinosaurs went extinct. The burrowing habits of early snakes might have helped to save them from going the way of the dinos during the major extinction event 65 million years ago.

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In addition to lizards like

Olindalacerta

, Four Feet probably ate salamanders and other small animals, the researchers believe. Both the ancient snake and its prey were "originally from Gondwana, the ancient continent formed by Africa and South America," Longrich said. As he says, "They're sort of a holdover from this lost world."

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