Snake fossil researchers

The Snake that Ate the Dinosaur

February 4, 2014 | by Elizabeth Wason

It’s 67 million years ago in what is now south Asia. A gigantic sauropod dinosaur female digs a shallow hole with one of her four huge feet and lays somewhere between six and a dozen six-inch eggs. She swings the tall stalk of her neck around to peer at the eggs one last time before she sweeps a thin layer of insulating leaves and dirt over the nest and moves away. The eggs, untended, lie in a shallow pit on the swampy bank of the river.

An egg splinters. A snout pokes out of the cracks. A hungry snake bellies up to the nest and coils its long body to get comfortable with its intended meal. The hefty snake rests its head on one of its coils, facing the egg as it’s just about to hatch.

The sauropod hatchling—its bones still a bit soft—stumbles from the egg fragments, completely unaware of the predator lurking nearby. The snake rises and prepares to strike the dinosaur.

And BAM! A mucky avalanche inundates everything. The snake stays forever poised to eat the dinosaur hatchling. The baby sauropod forever escapes that fate but gets an equally deadly surprise.

The snake that almost ate the dinosaur becomes instantaneously preserved under sediment for millions and millions of years.

It’s 1984, Gujarat, India

Paleontologist and dinosaur egg expert Dhananjay Mohabey uncovers a number of eggs in several nests during a field expedition in western India. Ancient eggs happen to be relatively common in western and central India—every local museum has them on display.

However, Mohabey notices that one of the 67-million-year-old nests contains the bones of a sauropod hatchling—the only fossilized sauropod hatchling in the entire world (at the time).

Still, the ancient snake stays unseen among the eggs.

2001, on the Side of the Road in India

Jeffrey A. Wilson steps out of the car to stretch his legs. He’s a recent Ph.D. graduate visiting India, trying to figure out a long-term research plan (later, he becomes Associate Curator in LSA’s Museum of Paleontology and an associate professor in LSA’s Department of Earth and Environmental Sciences). He notices parts of a snake skeleton on the side of the road. “I picked up the snake vertebrae,” he recalls. “Just to pass the time on the road. It’s hard not to, if you’re interested in anatomy.”

Wilson wishes that his field season were going better. He’s dug up a couple specimens on this trip, but he hasn’t found much. The digs are a bust, but this means he’s got time to explore the natural history museums in the area. In fact, he’s on his way to one, where he’ll meet Mohabey. Wilson has spent much of his scientific energy studying sauropod dinosaurs, and he’s looking forward to finally seeing Mohabey’s sauropod hatchling fossil in person. Wilson drapes the snake bones across the dashboard of the car and continues on to Mohabey’s lab.

Mohabey, a gracious, open host, gives a thorough tour, including the sauropod fossil that Wilson is eager to see. Embedded in the stony matrix is a chain of small bones. “Oh!” Wilson exclaims to himself, “There’s the zygosphene-zygantrum articulation!” Translation: Wilson spots the unmistakable interlocking vertebrae of a snake’s spine.

Finally, the snake predator has been caught hiding in the dinosaur nest.

“I think,” Wilson ventures aloud to Mohabey, “this fossil might be more interesting than even you thought when you described it.”

Part of the fossil originally unearthed by Mohabey, after preparation by Sanders, containing the snake vertebrae that Wilson recognized.

2004, Ann Arbor

After three years of bureaucratic delay, Wilson and Mohabey get clearance from the Indian government to temporarily transport the fossil to the University of Michigan, where it can be cleaned, prepared, and replicated for detailed study.

In LSA’s Museum of Paleontology, chief vertebrate preparator Bill Sanders uses tiny electric jackhammers called air scribes to shave away, grain by grain, the sediment that encloses the fossil bones. Sanders applies formic acid to loosen the stony matrix; he waves ducts suspended from the ceiling to vacuum dust out of the air. The process takes more than a year.

And now the fossil fully emerges: a snake skull with lower jaws, palate, and braincase; a snake’s coiled vertebrae and ribs; the eggs; fragmented eggshells; and the sauropod hatchling, with shoulder blade, ribs, and leg bone. It’s thrilling. Snakes are exceedingly rare in the fossil record. Typically, they include individual bones. Only a handful of nearly complete snake fossils from the dinosaur era exist.

The team invites snake expert and LSA alumnus Jason Head (’95) to examine the fossil. He notes the unique shape and number of the openings in the braincase through which cranial nerves would have passed. The snake, he declares, is a previously unknown species.

Fossil drawing

Fossil snake preserved in a sauropod nest with baby dinosaur, crushed egg fragments, and unhatched eggs.

2010, News Spreads

The team shares their news with the world. They name the snake Sanajeh indicus, meaning “ancient gaped one from greater India.” Sanajeh could not have swallowed a large sauropod egg, because it lacks the anatomical specializations in the skull and jaws that allow modern snakes to achieve a much wider gape than animals of comparable size. But the ancient snake could fit hatchlings into its mouth.

The preserved positions of the snake and hatchling in the fossil suggest that Sanajeh lay in wait for sauropod hatchlings to emerge, striking as the baby dinosaurs left the safety of their eggs.

February 15, 2014, Ann Arbor

Wilson and Mohabey will reunite to tell their story of this remarkable fossil in person, in a lecture titled “India Before the Himalayas: When Snakes Ate Dinosaurs.” This Farrand Memorial Lecture coincides with LSA’s India theme semester and celebrates the installation of a new permanent exhibit at the U-M Museum of Natural History. The exhibit will feature a life-sized, hand-painted sculpture based on the fossil that preserves the snake forever poised to attack the dinosaur, the split second before a sandy deluge smothered the scene.

“Discovery is never this ‘poof’ thing that happens in an instant,” Wilson says. After all, the snake stayed hidden in the dinosaur nest for 67 million years. “There are small and large advances along the way; sometimes you’re stalled, sometimes you’re on the wrong track. It’s a process. An odyssey,” he says, of discovery.

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