Prairie rattlesnake
© Jack Goldfarb, Texas Tech University

Meet the Ancient Squamates

There aren't many early squamate fossils, and snake fossils are among the rarest. No one is sure, then, from which group snakes descended, or when. But new fossils suggest that the snake ancestor lived on land, possibly in underground burrows. And because several different kinds of snakes appear in the fossil record by about 100 million years ago, scientists know that the "first" snake species must have lived millions of years earlier.

Biggest Snake Ever

An average Madtsoia (mad-TSOY-uh) was about 9 meters (30 feet) long. Scientists think the biggest ones may have reached 14 meters (46 feet)--the length of a school bus! Giant snakes constrict, or squeeze, their prey-and given Madtsoia's size, its prey was probably just about anything around it.

Deadly Liquid

Venom--a toxic mix of chemicals produced by special glands near the jaw--is a way of making sure the meal stops struggling before the snake starts swallowing. Venom also helps in digestion, breaking down a prey animal's tissues even before it gets to the stomach. How deadly is venom? That depends on the snake species, on how much venom is injected in any given bite and even on the species bitten. Animals that routinely hunt venomous snakes can be fairly immune.

Walking Jaws

Snakes' jaws are made up of bones connected by stretchy tendons and ligaments. The left and right sides can move independently; that means one side may be "walking" forward on the prey animal while the other side grips and pulls it backward. The python has many curved teeth-more than 200 in some species, including four separate rows in the upper part of its mouth. These teeth hold the prey as it moves toward the throat.

Open Wide

With closed jaws, the head of the 10-foot Reticulated Python is about the size of an adult human fist. When its jaws are open as wide as they can go, the snake could swallow a whole wild pig. How? A jaw composed of many bones connected to one another by incredibly tough and stretchy ligaments--and covered by equally stretchy skin-is part of the trick.

Delivering Venom

Fangs are teeth with one main function: getting venom into prey or predators. The evolution of fangs is complex, but scientists recognize three basic patterns in the 450 or so species of venomous snakes. The length of the bone in which the fang sits is what makes the patterns different.