Could T. rex catch a duckbill? And other dino questions answered.

[Ed. note: Recently, a reader named Wyatt left a comment on the blog asking HMNS Curator of Paleontology Dr. Bob Bakker a few questions about dinosaurs for a high school paper. We thought we'd share the answers with everyone - as well as wish Wyatt luck with his paper.]

1) Which predatory dino was the largest?

T-Rex Dinosaur
Creative Commons License photo credit: Scott Kinmartin

The longest probably were the North African spinosaurs or the Argentine giganotosaurs; both families pushed 50 feet.

But tyrannosaurs were chunkier – thicker neck and torso. So tyrannosaurs would be heavier for any given length. A 40 foot long tyrannosaur would be heavier than a 50 foot spinosaur.

Strongest bite was had by the tyrannosaurs – much wider across the back of the head than giganotosaurs or spinosaurs.

2)  Which would dominate?

That depends on the habitat, geography and geological time. Big tyrannosaurs didn’t live with spinosaurs or giganotosaurs. Tyrannosaurs are restricted to Mongolia, China and North America. Tyrannosaurs did live with many kinds of raptors – including Velociraptor, Bambiraptor, Dromaeosaurus, Saurornitholestes. 

All raptors are smaller than all Late Cretaceous tyrannosaurs. The smallest tyrannosaur is Nanotyrannus, Late Cretaceous of North America, about 1,000 pounds in weight. The biggest raptor of the time was only 100 pounds or so.

Tyrannosaur
Creative Commons License photo credit: matsuyuki

But…..there were many more raptors alive at one time than Nanotyrannus. Just like today – there are many more coyotes than grizzly bears. Raptors were too small to attack adult Triceratops or duck-bills. But tyrannosaurs were too big to capture small, nimble prey, such as furry mammals, birds, lizards, and little herbivorous dinosaurs like Parksosaurus.

Spinosaurs have teeth like those of big crocodiles and probably ate fish and ocean-going reptiles like sea-turtles. Even if spinosaurs and tyrannosaurs lived in the same spot, they would have eaten totally different food.

So, who is “dominant” depends on what sort of prey is being hunted.

3) How do we find out what a big predator ate and how it caught it’s food?

By careful comparison with the design of living animals and analysis of the habitat clues left in the rocks.

Example:  Tyrannosaurus rex.

Commonest prey animal in the same sediment: the duck-bill Edmontosaurus.

Could T. rex catch a duck-bill?  Some scientists say that T. rex was a stumble-bum, limited to a slow walk. They say that we could walk away from a charging T. rex.

Bio-mechanical test:  Among big animals today, faster animals have longer ankle bones (they’re called “metatarsals.”) Look at a lion and a cheetah. Both are cats. The cheetah is much faster. Check out the hind legs. Who has longer metatarsal ankle bones, compared to the thigh?

The cheetah does.

Now let’s compare a duck-bill with a T. rex. The hind legs are built to the same general bird-like plan. Who has longer metatarsal ankle bones?

The T. rex.  So we can conclude that a T. rex really could chase down a duckbill.

How could the duck-bill get away?  Here’s one theory: The abundance of turtle fossils, gators, crocs, and salamanders show that the habitat was warm, wet and supported dense thickets and woodlands.  A duck-bill didn’t have to run away. It could hide in tangled vegetation.

5 thoughts on “Could T. rex catch a duckbill? And other dino questions answered.

  1. I am just wandering but I have noticed Duckbills appear to have good communication skills based on the varied “head gear” or resonating chambers is it possible they could have capitalised on this ability to make an early escape from a lurking T-rex? Just say if you have a big herd of Duckbills feeding and one happens to notice a T rex getting a little to close so he or she sounds the alarm alerting the herd to the rex’s presence causing a mass exodus.

    Is this probable?

  2. Also to add I have noticed a lot animals today break the predator’s line of site forcing the predator to re-evaluate and calculate its next move. Did tyrannosaurus have the cognitive capability to think quick enough in order to lock onto a new target?

  3. Hi Joel,

    Dr Bakker sent the following reply:

    “Duck-Bill Sonic Blast.

    Yes, indeed, duck-bills were highly social and noisy communicators. The head crests served as visual i.d. badges and marks of rank. Old males had the biggest crests. Each species tended to evolve its signature cranial displays.

    Plus – as Professor Wiman suggested back in the 1920’s, the hollow skull crests were osteological woodwind instruments. Exhaling forcefully produced notes – loud notes. We know that elephants, rhinos and hippos use hi-energy, lo-frequency sound to send messages up to ten miles or more – it’s called “infra-sound” and the lo frequency does a better job traveling through trees, hills, and the ground.

    Mass burials of hundreds of duck-bills all in one sand bar is evidence that they moved in large herds and occasionally suffered mega-mortality in river crossings, as do giant herds of zebra and wildebeest today. Honking could spread alarms through the duck-bill herd instantly.

    Deep, powerful sound was a weapon as well. Blasts of infrasound will scramble a predator’s mental faculties.

    How smart was T. rex? Smarter than a crocodile; way smarter than tortoise. Adult crocs are clever predators, having learned over many seasons how to ambush prey…..so I figure a mature rex would have acquired some useful tactical skills in handling horned dinosaur counter-attacks and the confusing geometry of a thousand-member duck-bill herd.”

    Hope this answers your question – and thanks for reading the blog!

  4. There’s no doubt tyrannosaurs could catch hadrosaurs. Look at the bite marks on the DMNS Edmontosaurus. In addition, tyrannosaur stomach contents include hadrosaur bones.

  5. False, the T-Rex wasn’t the largest predatory dinosaur, according to national geographic was the Mapusaurus which being even larger than the former largest Giganotosaurus, being 40 feet long living about 100 million years ago. Nice try though :D.

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