Pleistocene Park?

Advances in genetics continue to inspire dreams of dinosaur clones but suffer from one problematic missing ingredient: DNA. The oldest DNA on record was extracted from an 800,000-year-old Greenland ice core, but in general the maximum survival age of genetic molecules probably falls more in the range of 100,000-200,000 years (one million at most). At best, that places mammoths, giant ground sloths and saber-tooth cats within reach, but not dinosaurs [sources: Gannon; Kolata; Mabry].

Egged on by Advances

In the 1994 movie "Dumb and Dumber," Mary Swanson tells Lloyd Christmas that their chances of ending up together are "one out of a million," to which he replies, "So you're telling me there's a chance."

Paleontologists must sometimes feel like Mary when answering questions about dinosaur de-extinction. They must also wonder how so many people could watch "Jurassic Park" and its sequels and miss the persistent theme of unintended consequences.

Does the discovery of dino embryos open up a new avenue to reptilian rebirth? The answer is no. Dinosaur eggs are tens to hundreds of millions of years past their Use By date, and fossilized to boot -- not exactly prime incubator material. As for the embryos, they are just so many piles of bone. Not much help there.

What about the organic material -- have we finally dug up dinosaur DNA? Not exactly. Paleontological circles have been debating possible organic tissue finds for years, but they have yet to find DNA (and likely never will -- see sidebar).

Take the Tyrannosaurus rex, for example. In 2005, scientists using weak acid to demineralize Tyrannosaurus bone pulled soft, pliable "tissues" from the remains, including bits that resembled bone cells, red blood cells and blood vessels. Later finds provided further samples of preserved tissues from a variety of species and time periods, suggesting this discovery was no fluke [sources: Kaye et al.; Schweitzer et al.; Schweitzer et al.].

Needless to say, people got a little excited. In a game of inches like paleontology, such a find amounted to a touchdown, but research referees soon rolled back the scoreboard. Upon further review via carbon dating and scanning electron microscopy, they announced that the stringy bits and hollows were not dinosaur tissues but bacterial biofilms -- collections of bacteria bound together by polysaccharides, proteins and/or DNA. They might look the part, but they actually have more in common with tooth plaque than dinosaur cells [sources: Bayles; Kaye et al.].

Whatever their nature, the finds made paleontologists wonder; Might the real thing be out there, waiting to be discovered? They adjusted their techniques and, with the Lufengosaurus nest, struck pay dirt. Exciting? Absolutely. Organic? Sure. DNA? Not by a long shot [source: Reisz et al.].

But suppose it had been?