One of Trek Birmingham’s themes is the celebration of the region’s outstanding biological diversity. So why, you might ask, are dinosaurs relevant? If you’ve already read our Trek Birmingham essays about the area, you get that it’s important to know about the region’s geologic past before you can really understand the geology beneath our feet – and the origins of both Birmingham’s industry and the area’s spectacular biological diversity. Though they died out about 65.5 million years ago, dinosaurs once called Birmingham home. They scrambled across the region’s hills and grazed in what is now Jones Valley. Thus, dinosaurs and the other large reptiles from long ago are part of the region’s biological history. If that justification for writing about Birmingham’s dinosaurs seems like a stretch, how about this: dinosaurs are really cool and fun to learn about.
The McWane Science Center hosts a spectacular display of some of the 21 species of dinosaurs, plus other large reptiles, whose remains from the Late Cretaceous period (100–65.5 million years ago) have been recovered in Alabama. A team of scientists, museum curators, and artists worked together to display some of Alabama’s best reptilian fossils in natural settings that inspire visitors to imagine how these creatures lived back in their heyday.
What would it be like if you crossed timelines and went back to Birmingham in the Late Cretaceous period? This was the last phase of the Mesozoic Era (251–65.5 million years ago), a time when dinosaur diversity was at its peak and just before the mass extinction that killed off them and hundreds of other species (very likely caused by an asteroid that hit the Yucatan). Thanks to the work of geologists and paleontologists, we know enough about the Late Cretaceous to imagine such a journey in rich detail.
Upon your arrival in the Late Cretaceous period, you’d find yourself within a dense forest that would look something like the tropical rain forests of the Amazon. You’d see unfamiliar trees – including several primitive conifers – but also many ancestors of our modern plants abundant in Alabama today like willow, magnolia, sassafras, persimmon, and holly. Others would be tropical trees, including figs and palms.
You’d also quickly notice that Birmingham was hot and steamy, even more so that now, regardless of what time of year you visited. During the Cretaceous period, there were very high levels of carbon dioxide in the atmosphere – the heat-trapping gas primarily responsible for our climate-change crisis – and this helped a tropical climate to extend as far north as Greenland. In the Southeast, a continuous growing season and an abundance of tropical heat, rainfall, and atmospheric carbon dioxide promoted luxuriant plant growth.
The dense tropical forest in Birmingham would make it hard to see any dinosaurs. And worse, it would make it easier to be ambushed by one! Even climbing to the high ground in the region’s hills or mountain ridges wouldn’t help, since you’d have a difficult time seeing much from within a dense forest. So, imagine that you head for the coast to try to see dinosaurs and other large reptiles from a respectable distance.
Fortunately, the coast was a lot closer to Birmingham than it is today. For several reasons, including the warm climate and lack of polar ice, sea levels were higher now than at any other time in the planet’s history. You’d need to travel only about 12 miles south of the Birmingham metropolitan area to reach the shoreline. When you got there, you’d find a stunning coast where the Appalachian Mountains met the shores of the Gulf of Mexico. Here, the cliffs and promontories would make it safer for you to scan for large wildlife.
One of the first large creatures you might see would be huge flying reptiles with wingspans up to 24 feet. These were Pterosaurs, and they would have been a common sight along the coastline. Pterosaurs are not dinosaurs but are closely related. And despite having evolved powered flight, they are not ancestors to birds. Fossilized bones of one species from the genus Pteranodon have been recovered in Alabama. Recovered bones and a full replica of a Pteranodon are on display at the McWane Science Center. It’s thought that Pteranodons were fish hunters who soared high above the ocean and swooped down to snatch fish from the ocean’s surface. Nevertheless, you’d be wise to take cover whenever one sails by.
You’d also see signs of the herbivorous dinosaurs that fed in the swamps and thick coastal forests. There would be numerous tracks in the dunes bordering the forests, and, in the nearby swamps, you’d see signs of grazing and trampling. With time, you might spy a herd of Nodosaurs. These plant eaters were short, slow moving, and heavily armored. One of them, Nodosaurus, ranged in length from 11 to 22 feet and relied on sharp bony spikes around its neck and shoulders to protect it against attack from carnivorous dinosaurs. An 11-foot-long juvenile Nodosaurus skeleton is on display at the Center.
You might also see a member of the Ornithomimid family, or “bird mimic” dinosaurs. Ornithomimids were fast-moving dinosaurs that stood 11 feet tall and stretched 25 feet long. Their lack of teeth suggests to paleontologists that they gulped down fruit (and possibly insects) for nutrition. They were not heavily armored and would have relied on speed to evade predators. Armor would simply slow them down.
Stalking the Ornithomimids and other herbivorous dinosaurs were several intimidating carnivores. Some, such as the Dromaeosaur, were small, swift lizards up to nine feet long . The curators at the Center have created an exhibit where two Dromaeosaurs of the genus Deinonychus attack an Ornithomimid of the genus Gallimimus. Since the display includes replicas of their skeletons, you’ll just have to imagine the gore that would accompany such a scene. Dromaeosaurs could take down larger prey like Gallimimus with the long, retractable sharp claw on the second toe of each foot. They’d have to pounce to use this claw, which meant they would grasp, tear, and bite with their sharp teeth and fore-arm claws. Their backward-curving teeth suggest they quickly gulped down hunks of flesh during and after a kill. Why were they in a hurry? Because there were larger carnivores around that might take over their kill at any moment.
The largest of these carnivorous dinosaurs to hunt the southeastern forests was none other than Appalachiosaurus, or the Alabama Tyrannosaur, also on display at the Center. At 10 feet tall and 22 feet long, this top predator was just slightly smaller than its cousin, Tyrannosaurus Rex, who haunted western North America. Like other carnivorous dinosaurs, Appalachiosaurus likely ambushed its prey from the thick vegetation next to game trails and grazing areas.
There really wouldn’t be any safe place for soft, squishy animals like us in Alabama at the time. The oceans were patrolled by sharks and huge, fierce marine reptiles such as Plesiosaurs and Mosasaurs (look for the Mosasaur on display at the Center). Freshwater swamps were home to several species of crocodiles, including one with a four-foot-long skull. Even large plant-eating reptiles would pose a threat should you get too close to a nest or be in the path of a panicked herd escaping an attack. So, it’s probably for the best that you visit these animals from the safety of the McWane Science Center and use your imagination to journey back in time. -R. Scot Duncan