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A restoration of the Cretaceous snake Sanajeh about to gulp down a baby sauropod. Model by Tyler Keillor, photographed by Ximena Erickson.

In 1925, when Yale University paleontologist George Wieland published a paper titled “Dinosaur Extinction,” no one knew why the great archosaurs had disappeared. The fact that the extinction of the dinosaurs was even worth explaining was a new idea. From the time dinosaurs were initially described in the early 19th century through the beginning of the 20th, their existence and disappearance simply seemed to be part of a grand progression of life that required no special attention or explanation. Even when paleontologists began to puzzle over why the dinosaurs vanished, many thought that dinosaurs were inevitably doomed by strange, internal growth factors that made them so large, stupid and ornate that they could not possibly adapt to a changing world.

But Wieland took a slightly different view. While his paper was more opinion than science—there was nothing measured, quantified or tested in the article—Wieland believed that he had perhaps identified some of the “invisible influences” that triggered the demise of the dinosaurs. Egg-eaters were of primary concern.

Wieland was not the first to suggest that the destruction of dinosaur eggs led to the group’s extinction. As pointed out by Wieland himself, paleontologists Charles Immanuel Forsyth Major and Edward Drinker Cope had previously speculated that small mammals may have raided dinosaur nests so frequently that Triceratops and its Mesozoic ilk were incapable of reproducing successfully. This hypothesis seemed plausible in general, but Wieland disagreed about mammals being the primary culprits. Small Mesozoic mammals seemed too weak to break open tough dinosaur eggs, and the most voracious modern-day nest thieves seemed to be those reptiles capable of swallowing eggs whole. “The potent feeders on dinosaur eggs and young must be sought for amongst the dinosaurians themselves,” Wieland remarked, “and perchance, amongst the earliest varanids [monitor lizards] and boids [boa snakes].”

Wieland believed that egg-eating must have been rampant during the age of the dinosaurs. In fact, he thought that a diet of eggs may have even led to the evolution of some of the largest of all predatory dinosaurs. Considering the giant Tyrannosaurus, Wieland wrote, “What more likely than the immediate ancestors of this dinosaur got their first impulse toward gigantism on a diet of sauropod eggs, and that, aside from the varanids, the theropod dinosaurs were the great egg-eaters of all time?” The cruel irony of this idea was that the immense predatory dinosaurs also reproduced by laying eggs, and Wieland considered it “quite inferable” that their nests, in turn, would have been raided by smaller monitor lizards and snakes.

Dinosaurs were not entirely defenseless against such attacks. Though dinosaurs were often thought in the 1920s to be reptiles write large, Wieland speculated that dinosaurs would have provided some parental care, were probably more active than living lizards and crocodiles and, among the egg-eating varieties, may have even sought out unprotected nests in coordinated “droves.” “With such active and powerful beasts at the jungle-edge,” Wieland wrote, “life was varied and sanguinary, be it within scientific dignity to say so.” Unfortunately, an active and varied existence could not save the dinosaurs. Both ecological factors and the supposed inability of dinosaurs to change sealed the fate of the dinosaurs, Wieland concluded; the great loss of eggs and the “racial senility” of dinosaurs ultimately ushered the group into extinction.

When Wieland wrote his paper, he could only speculate about predation on dinosaur eggs and babies. In the decades since, however, paleontologists have turned up rare fossil evidence that small predators truly did snap up young dinosaurs in various stages of development. In 2010, paleontologists announced the discovery of Sanajeh, a late-Cretaceous snake that may have fed on the eggs of sauropod dinosaurs. Several years before that, a different team of paleontologists found several baby Psittacosaurus skeletons in the fossilized stomach contents of the opossum-sized mammal Repenomamus, and in a 1994 paper, paleontologist James Kirkland suggested that small crocodyliforms like the slender Fruitachampsa may have also gobbled up eggs and little dinosaurs since their bones are sometimes found in association with dinosaur nests.

Despite these recent discoveries and hypotheses, however, there is no indication whatsoever that dinosaurs were driven to extinction by egg-eaters, reptilian or otherwise. Perhaps such a view was tenable when only a few dinosaur genera were known and we understood very little about their ecology, but not now. We have a greatly revised understanding of what happened at the end of the Cretaceous—a mass extinction that wiped out not only the dinosaurs, but a vast swath of life forms on land and sea. There is no hint of a run on dinosaur eggs in the fossil record, and the various types of supposed egg predators lived alongside dinosaurs for millions of years without killing off their egg-laying food supply. Dinosaur eggs certainly were a nutritious resource that were undoubtedly exploited by carnivores and omnivores, but such depredations were not the keys to dinosaur extinction.

References:

Wieland, G. 1925. Dinosaur Extinction. American Naturalist. 59 (665): 557-565

A restoration of the island hadrosauroid Tethyshadros by Nobu Tamura. Image from Wikipedia.

Everyone knows what a “duck-billed” dinosaur was. This bit of shorthand has been permanently grafted onto the hadrosaurs—the widespread group of herbivorous dinosaurs with elongated skulls and what appear to be duck-like beaks.

The title made perfect sense during the early 20th century when these dinosaurs, such as Edmontosaurus and Parasaurolophus, were thought to be amphibious creatures that dabbled in the water for soft plants and escaped into Cretaceous lakes when predators came near. If the dinosaurs looked like monstrous ducks, then they must have acted like ducks. But that vision of paddling hadrosaurs was discarded decades ago. These dinosaurs were terrestrial animals, and discoveries of well-preserved hadrosaur beaks have indicated that the mouths of these dinosaurs were not so duck-like, after all. One beautifully preserved Edmontosaurus skull on display at the Natural History Museum of Los Angeles shows that the tough beak of this dinosaur ended in squared-off, almost vertical croppers and not a duck-like, spoon-shaped bill. The so-called duck-billed dinosaurs didn’t look like mallards at all. And one of the strangest variations in beak shape was found in a small, island-dwelling hadrosauroid described in 2009.

On the basis of a nearly complete and articulated skeleton, paleontologist Fabio Dalla Vecchia named the dinosaur Tethyshadros insularis. The name is a testament to where the dinosaur lived. During the time of Tethyshadros, around 71 million years ago, an ancient sea called Tethys covered most of southern Europe. This oceanic incursion created chains of islands, and it was on one of these islands—where Italy sits today—that Tethyshadros lived. More than that, the isolation of the dinosaur on the island might have been responsible for the dinosaur’s relatively small size (about 13 feet long) compared to its distant, North American cousins such as Edmontosaurus—it’s an example of a phenomenon called insular dwarfism that has been documented for other prehistoric herbivores, including dinosaurs.

But one of the most peculiar aspects of Tethyshadros was its beak. Instead of a long, low duck bill, the upper beak of this dinosaur was a ridged structure jutting out in a shape roughly reminiscent of a snowplow. And rather than being smooth, the margin of the upper beak was pointed, with the middle point being the largest. This general type of serrated beak has been seen before in iguanodontian dinosaurs—the stock from which hadrosaurs evolved, with Tethyshadros being closer to hadrosaurs than to the iguanodontians—but never before in such an extreme shape. Why Tethyshadros had such a strange beak is a mystery. As paleontologist Darren Naish wrote in his detailed summary of this new dinosaur, “Did [the beak spikes] help Tethyshadros to bite at specific food items? Were they for grooming? For display? The mind boggles.”

References:

Dalla Vecchia, F. (2009). Tethyshadros insularis, a new hadrosauroid dinosaur (Ornithischia) from the Upper Cretaceous of Italy Journal of Vertebrate Paleontology, 29 (4), 1100-1116 DOI: 10.1671/039.029.0428

A reconstruction of Tyrannosaurus rex on display at the National Museum of Natural History. Photo by the author.

I can’t help feel bad for Tyrannosaurus. The dinosaur’s relatively minuscule arms are a near-constant source of ridicule. It doesn’t matter that there were other fearsome predatory dinosaurs with even smaller and apparently useless arms—the short arms of the “tyrant king” are a cruel evolutionary joke.

All the same, the tumblr blog T-Rex Trying… is a whimsical line-drawing catalog of all the things Tyrannosaurus couldn’t do with those small arms. Everything from cross-country skiing to simply counting to five would have posed a challenge, although I think my personal favorite is Tyrannosaurus trying to navigate the sneeze-guard at a buffet. Although such a scenario assumes that Tyrannosaurus would have had the manners to stand in line for the steam-tray fare and would not have gobbled up the bacon- and potato-stuffed clientele….

About 110 million years ago, an ankylosaur settled on the bottom of a Cretaceous sea. This was no place for a dinosaur. No dinosaurs were adapted to a marine lifestyle, and the heavily armored ankylosaurs were probably the least suited to paddling around in the water. Yet, almost a year ago, shovel operator Shawn Funk found an ankylosaur in the marine, Early Cretaceous sediments at a Suncor mine in northern Alberta. How did the dinosaur get there?

Donald Henderson, curator of dinosaurs at the Royal Tyrrell Museum, explained how this dinosaur died, was preserved and was discovered in a recent lecture for the Royal Tyrrell Museum Speaker Series. Almost everything about the discovery was lucky. The dinosaur just happened to settle in a place where sediment quickly covered its body; the carcass was not torn apart by scavengers; the shovel operator who stumbled across the ankylosaur recognized that he found something potentially significant and the discovery of the dinosaur in the mine meant that paleontologists had lots of heavy machinery on hand to help excavate the skeleton.

But the strangest aspect of the find is the ecological context of the dinosaur. This ankylosaur must have lived along the coastline of the great Western Interior Seaway which once split North America into two. But that was many, many miles away from where the skeleton was found. Exactly how the dinosaur died is unknown, but as Henderson notes, the carcass undoubtedly floated upside-down through the sea. The gases from decomposition gave the body enough buoyancy to travel—what paleontologists commonly refer to as a “bloat and float” scenario.

Dinosaur, Colorado's bizarre, long-snouted Triceratops. Photo by author.

Last week I asked you submit your favorite atrocious roadside dinosaurs. While the sculptures along the main drag of Dinosaur, Colorado come close to the top of the list, my vote last week went to the ugly, ugly dinosaurs outside Stewart’s Petrified Wood near Arizona’s Petrified Forest National Park. Readers sent in a few additional contenders for the title.

Photo by Mark Ryan.

Reader Mark Ryan sent in this sad, decaying dinosaur that stands near Interstate 15 in the vicinity of Victorville, California. No wonder the dinosaur needs those metal rods to support itself—its legs look like they’re made of cooked noodles.

Cowboys and dinosaurs, spotted in Natural Bridge, Virginia. Photo courtesy Kathy Krein.

A regular favorite of Dinosaur Tracking readers is the truly strange Dinosaur Kingdom in Natural Bridge, Virginia. Suggested as a top choice for weird dinosaurs by reader Laura Wilson, this tourist trap features a peculiar southern mash-up of dinosaurs and the Civil War—Union Soldiers are chomped on and terrorized by Mesozoic monstrosities. This particular shot, sent in last year by Kathy Krein, features a rather surprised looking cowboy who looks as if he’s only just begun to realize that riding a deinonychosaur was a horrible decision.

Photo by Kelly Enright.

Reader Kelly Enright sent in a set of several dinosaurian abominations from around the country. This one, complete with glowing eyes, stands guard over Goony Golf in New York.

Photo by Kelly Enright.

While not actually a dinosaur, this boxy mosasaur outside Big Mike’s Rocks & Gifts in Kentucky deserves an honorable mention, especially since the poor thing is stranded hundreds of miles from the nearest ocean.

Photo by Kelly Enright.

While not the absolute worst dinosaur I have ever seen, this Tyrannosaurus at the entrance to Kentucky’s Dinosaur World is one of the creepiest. So if the head is up there, and the legs are on either side, what part of the dinosaur am I walking into, exactly?

Photo by Kelly Enright.

We may have a new winner! While this automotive Triceratops—I think?—from Hanksville, Utah does win some bonus points for recycling, my first thought when I opened the image was “Oh geez! Kill it with fire!” This dinosaur is a junkyard nightmare, and surely a top contender for the worst roadside dinosaur ever.