Theropoda contains all of the carnivorous dinosaurs. Let’s discuss some of the f

Question

Theropoda contains all of the carnivorous dinosaurs. Let’s discuss some of the features sported by various meat-eating members of this clade related to their flesh-rending lifestyles. As the unit progresses, this list of features will become substantially long. If you cannot think of a way to expand on the list, use components listed to design your ideal “ultimate predatory dinosaur”. Be sure to explain why your hypothetical predator is so superior. You should elaborate on how you define superiority. Do not just list a known species and tell why you think it is the ultimate predator. I want you to create monsters surpassing anything we’ve discovered using features that have evolved in known groups as examples. No fire-breathing nuclear powered mecha-Godzillas with laser pupils please.

Explanation / Answer

Some dinosaurs were carnivores (meat-eaters) but most were herbivores (plant-eaters). This is true for all animal populations. In any food chain, there have to be more organisms at the lower levels of the chain because the transfer of food energy is inefficient and much of the energy is lost at each stage of the process.

A large number of plants (called producers or autotrophs) can support a smaller number of plant-eaters (called primary consumers). These plant-eaters are eaten by a smaller number of carnivores (secondary consumers).

For example, it may have taken hundreds of acres of plants to feed a small group of Triceratops. These Triceratops could supply a single T. rex with enough food to survive over its lifetime.

If you look at dinosaur genera, roughly 65 percent of the dinosaurs were plant eaters and 35 percent were meat-eaters (or omnivores). If you look at the number of actual fossils found, the percentage of plant-eaters increases, since many fossils of some of the plant-eaters have been found. For example, over a hundred Protoceratops fossils have been found, but only about a dozen T. rex fossils have been found.

Carnivores
Meat-eaters (carnivores or theropods) need to have some way to get meat. Carnivorous dinosaurs usually had long, strong legs so that they could run quickly in order to catch their prey. They also needed large, strong jaws, sharp teeth, and deadly claws so they could kill and then tear apart the prey. Good eyesight, a keen sense of smell, and a large brain to plan hunting strategies are also very important for successful hunting. Many of the carnivores (like Deinonychus, Coelophysis and Velociraptor) may have hunted in packs, so social cooperation was necessary for a good hunt for some species. Animals that are primarily scavengers (animals that eat meat that they did not kill themselves) need very sharp teeth and strong jaws for tearing into less than prime cuts of meat, and breaking bones to get the nutritious bone marrow. Most carnivores are scavengers when given the opportunity. Some dinosaurs were fish eaters, including Baryonyx and Suchomimus. Spinosaurus may have been a good swimmer (it had paddle-like feet similar to those of water birds). A few dinosaurs (including Coelophysis) have been found with small, fossilized animals within their fossil, giving information about their diet. Some dinosaurs may have even been cannibals, eating their own kind.

How dramatically some hypotheses can change! Back in the 1920s, when the rst American Museumof Natural History (AMNH) expedition went to Mongolia, some of the most spectacular nds werenests containing dinosaur eggs. The nests were scooped in the sand, and each contained 20 or 30sausage-shaped eggs, arranged in rough circles, and pointing in to the middle. Around the nests wereskeletons of the plant-eating ceratopsian dinosaur

Protoceratops

and a skinny, nearly2-meter long, esh-eating dinosaur. This esh eater had a long neck, a narrow skull and jaws withno teeth, and strong arms with long bony ngers. Henry Faireld Osborn (1857–1935), the famedpaleontologist and autocratic director of the AMNH, named this theropod

Oviraptor

, which means“egg thief”. A diorama was constructed at the AMNH, and photographs and dioramas of the scenewere seen in books and magazines worldwide:

Oviraptor

was the mean egg thief who menacedinnocent little

Protoceratops

as she tried to protect her nests and babies.Then, in 1993, the AMNH sent another expedition to Mongolia, and the whole story turned onits head. More nests were found, and the researchers collected some eggs. Amazingly, they also founda whole skeleton of an

Oviraptor

apparently sitting on top of a nest . It was crouchingdown, and had its arms extended in a broad circle, as if covering or protecting the whole nest. Theresearchers X-rayed the eggs back in the lab, and found one contained an unhatched embryo. Theypainstakingly dissected the eggshell and sediment away to expose the tiny incomplete bones insidethe egg .

Tyrannosaurus rexmay have been a flesh-eating terror but many of his closest relatives were more content with vegetarian fare, a new analysis by Field Museum scientists has found. The scientists, Lindsay Zanno and Peter Makovicky, who will publish their findings in the journal Proceedings of the National Academy of Sciences, used statistical analyses to determine the diet of 90 species of theropod dinosaurs. Their results challenge the conventional view that nearly all theropods hunted prey, especially those closest to the ancestors of birds. Rather, Zanno and Makovicky show that among the most bird-like dinosaurs--known as coelurosaurs--plant eating was a common way of life. "Most theropods are clearly adapted to a predatory lifestyle, but somewhere on the line to birds, predatory dinosaurs went soft," Zanno says.

Coelurosaurian theropods were an extremely successful group of dinosaurs throughout the Cretaceous Period (145-65 million years ago) and many different species of coelurosaurs inhabited the same ancient environments but scientists have yet to figure out why. One theory is that the break up of continents and origin of new habitat opened up new dietary niches for coelurosaurs to explore. Zanno and Makovicky speculate that dietary diversification also may have played a role in their success. "The ability to eat plant materials may have played a pivotal role in allowing coelurosaurian dinosaurs to achieve such remarkable species diversity," Zanno noted, "but more study is needed to understand what role dietary shifts may play in evolutionary processes."

Because ceolurosaurian dinosaurs include the closest extinct relatives of birds, understanding their biology is also extremely important to understanding how, why, and under what conditions birds evolved and first took flight.

"We don't know what drove the ancestors to birds to take flight," she says, "seeking food in the trees is just one of many possibilities."

Using statistical analysis to find correlations between physical traits and diet could offer a new window as to how evolution works, the researchers said, and these techniques could be used to provide new insight into the common practice of becoming an herbivore throughout vertebrate history. Makovicky summarizes, "Being able to establish diet in extinct animals with confidence will allow us to start tackling even broader questions, such as whether animals tend to increase in body and diversity when they evolve herbivory."

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