Dinosaur Island supports cannibalistic T. Rex

Dinosaur Island supports cannibalistic dinosaurs! Just click on the 'cannibal' box.

Dinosaur Island supports cannibalistic dinosaurs! Just click on the ‘cannibal’ box.

As recently reported in Science Magazine (here), “[t]he group of ferocious meat-eating dinosaurs known as tyrannosaurs—of which the most famous member is Tyrannosaurus rex—may have sometimes turned their sharp teeth on each other.” In other words, they were cannibals! “In a study published online this week in PeerJ, the researchers conclude from both the spacing and shape of the puncture marks on its skull that it was bitten by another tyrannosaur—quite possibly another Daspletosaurus—while it was still alive, probably as the result of a dino-on-dino fight.”

Dinosaur Island supports such behavior. When creating a dinosaur species in the simulation, just click on the ‘cannibal’ box in the ‘diet’ section.


New Research: Varied Diets in Dinosaurs Promoted Coexistence

Ceratopsidae, a family of thick-skulled, horned dinosaurs, including the well-known Triceratops, had teeth that functioned as shears, suggesting that they consumed particularly tough plants

Ceratopsidae, a family of thick-skulled, horned dinosaurs, including the well-known Triceratops, had teeth that functioned as shears, suggesting that they consumed particularly tough plants

In an article recently published in PLOS ONE, University of Calgary researcher, and friend of Dinosaur Island, Dr. Jordan Mallon, explains how dinosaur teeth give us insight into the varied diets of dinosaurs and how they co-exited for hundreds of millions of year in a complex ecosystem (the very theme of Dinosaur Island). Link to write-up about the article here. Link to the PLOS ONE article here.


Creating a combat model for T. rex versus Edmontosaurus regalis.

A T. rex is attacking an Edmontosaurus while it's companions flee (screen capture of the AI test bed program). Click to enlarge.(screen capture of the AI test bed program).

A T. rex (Bob) is attacking an Edmontosaurus (Julie) while its companions (Gertie & Muffie) flee (screen capture of the AI test bed program). Click to enlarge.

We are at the point in the development of the AI routines for the inhabitants of Dinosaur Island where it is time to make decisions about the combat models used to determine the resolution of hostile encounters. As shown in the screen capture of the Dinosaur Island AI testbed program (above), the simulation is placing the dinosaurs in various appropriate states such as: resting, eating, looking for food, looking for water, stalking prey, moving towards water, moving towards food, drinking, fighting and fleeing.

My first thought on the subject of modeling combat between T. rex and Edmontosaurus regalis, the first two resident species on the island, was that it would be handled similar to ‘melee combat’ models that I had previously used for my wargames.

Below is a page from the manual for UMS II: Nations at War explaining the 20 variable equation used to decide combat between tactical units.

The 20 variable equation used to calculate combat in our UMS II: Nations at War (c. 1992). (Scan from user's manual). Click to enlarge.

The 20 variable equation used to calculate combat in our UMS II: Nations at War (1989). Scan from user’s manual. Click to enlarge.

I was envisioning something similar for Dinosaur Island until I happened to see this video (below) which includes a sequence (starting at 4:45) describing hypothetical Edmontosaurus and T. rex combat.

What I took away from the video was:

  • Edmontosaurus regalis  is bigger than I thought. I understood the size mathematically and that they could easily grow up to 13 meters (~ 40 feet) but it wasn’t until I saw this video that it was put in perspective, “they were as big as a railroad car.” And, “they could look into a second story window.”
  • The tail of an adult ‘bull’ Edmontosaurus regalis  was a formidable weapon.
  • T. rex, like many predators, would have preferred to attack adolescent or sick animals rather than encounter a full-size, and potentially lethal, ‘bull’.
  • The correct pronunciation is Ed-MONT-o-saur-us. I’ve been saying it wrong for the last six months!

While there is still debate about whether T. rex was a predator or a scavenger (“Tyrannosaurus rex may have been an apex predator, preying upon hadrosaurs, ceratopsians, and possibly sauropods, although some experts have suggested it was primarily a scavenger. The debate over Tyrannosaurus as apex predator or scavenger is among the longest running in paleontology.” – Wikipedia) we know of at least once case where a T. rex tooth was found in an Edmontosaurus tail that had healed from the attack (“T. rex Tooth Crown Found Embedded in an Edmontosaurus Tail – Predatory Behaviour?” “The healed bone growth indicates that the duck-billed dinosaur survived this encounter.  In February of this year, researchers from the University of Kansas and Florida reported on the discovery of evidence of a scar on fossilised skin tissue from just above the eye of an Edmontosaurus.  In a paper, published in “Cretaceous Research”, the scientists concluded that this too was evidence of an attack of a T. rex on an Edmontosaurus.”). From this we can conclude that:

  • Sometimes T. rex did attack a living Edmontosaurus.
  • Sometimes the Edmontosaurus survived the attack.

Furthermore, we know that some T. rex had suffered bone injuries during their lifetime (“An injury to the right shoulder region of Sue resulted in a damaged shoulder blade, a torn tendon in the right arm, and three broken ribs. This damage subsequently healed (though one rib healed into two separate pieces), indicating Sue survived the incident.” – Wikipedia) consistent with the type of damage that a 5 meter long tail (described as being “like a baseball bat,” in the above, video) could inflict.

In other words, combat between T. rex and Edmontosaurus regalis was not a foregone conclusion. Indeed, it was entirely possible that the Edmontosaurus could walk away unscathed while the T. rex could suffer some broken bones.

The AI for Dinosaur Island will reflect this. When deciding if the T. rex will attack the AI will have to analyze the T. rex‘s chances of victory and potential injuries (risk versus reward) considering the size of the T. rex, the age of the T. rex, the health of the T. rex, the size of the prey, the age of the prey and the health of the prey. And, when the two dinosaurs actually engage in combat the tactics employed by both will probably decide the outcome.

If the T. rex can sneak up on the Edmontosaurus until they are within 50 meters or less and then close the distance with a rush the advantage would certainly lie with the predator. If the Edmontosaurus has forewarning of the impending attack it would either attempt to flee or stand its ground and assume a defensive posture.

There is reason to believe that both Edmontosaurus and T. rex had well developed olfactory bulbs in their brains and smell was an important sense for both animals. We will add wind (and wind direction) to Dinosaur Island and incorporate this into the AI routines that control the dinosaurs. Predators will attempt to get ‘upwind’ of their prey; prey animals will ‘sniff’ the wind and respond if they smell a T. rex even if they can’t see it (see “Dinosaurs, tanks and line of sight algorithms” here).


Herbiverous dinosaurs getting along at the salad bar

What does your dinosaur eat? How much energy does he need? How much energy is produced when he is eaten?

You can select what each species of dinosaur eats on Dinosaur Island (screen capture, click to enlarge).

On Dinosaur Island you can select what each species eats. A recent article (quoted at length, below) shows why this is necessary to simultaneously maintain numerous species of large herbivores.

A new study by a Canadian Museum of Nature scientist helps answer a long-standing question in palaeontology — how numerous species of large, plant-eating dinosaurs could co-exist successfully over geological time.

Dr. Jordan Mallon, a post-doctoral fellow at the museum, tackled the question by measuring and analyzing characteristics of nearly 100 dinosaur skulls recovered from the Dinosaur Park Formation in Alberta, Canada. The specimens now reside in major fossil collections across the world, including the collections of the Canadian Museum of Nature. The work was undertaken as part of his doctoral thesis at the University of Calgary under the supervision of Dr. Jason Anderson.

Mallon’s results, published in the July 10, 2013 issue of the open-access journal PLOS ONE, indicate that these megaherbivores (all weighing greater than 1,000 kg) had differing skull characteristics that would have allowed them to specialize in eating different types of vegetation. The results support a concept known as niche partitioning, which dates to the 19th-century studies of Charles Darwin and came into its own in the 1950s with the development of the science of ecology.

A link to the article is here: