What does an alligator think about a Tyrannosaurus Rex?

In October 2016, Jason McDonald, 35, who works at the Colorado Gators Reptile Park, disguised himself as a T-Rex to taunt a 500 lb alligator with fish. But why? Well, for fun, and the park worker insists he was making Morris, as the reptile is known, “work for his food” because he had gotten “chunky.”
Adams later admitted he couldn’t see in the costume and joked he’d be having a “bad day” if the predator came out of the water. 

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The photo made me wonder if an alligator would possibly have a genetic memory of T-Rex. Would the alligator look at the size of the mouth of an opponent and back off? Some alligator ancestors could eat a T-Rex.

Biologists have found in a study of all 23 living crocodilian species that crocodiles can kill with the strongest bite force measured for any living animal. The … bite forces of the largest extinct crocodilians exceeded 23,000 pounds, a force two-times greater than the mighty Tyrannosaurus rex.

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Alligators are not crocodiles, but are they crocodilians? What is the evolutionary link between alligators and crocodiles?

While many of today’s top predators are more recent products of evolution, the modern American alligator is a reptile from another time.

New research shows these prehistoric-looking creatures have remained virtually untouched by major evolutionary change for at least 8 million years, and may be up to 6 million years older than previously thought. Besides some sharks and a handful of others, very few living vertebrate species have such a long duration in the fossil record with so little change.

“If we could step back in time 8 million years, you’d basically see the same animal crawling around then as you would see today in the Southeast. Even 30 million years ago, they didn’t look much different,” says Evan Whiting, a former University of Florida undergraduate and the lead author of two studies published during summer 2016 in the Journal of Herpetology and Palaeogeography, Palaeoclimatology, Palaeoecology that document the alligator’s evolution—or lack thereof.

“We were surprised to find fossil alligators from this deep in time that actually belong to the living species, rather than an extinct one,” he says.

… While modern alligators do look prehistoric, study authors say they are not somehow immune to evolution. On the contrary, they are the result of an incredibly ancient evolutionary line. The group they belong to, Crocodylia, has been around for at least 84 million years and has diverse ancestors dating as far back as the Triassic, more than 200 million years ago.

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Alligators are in a family under the order Crocodilia, which also contains the family for true crocodiles. Alligators are crocodilians.

The Crocodilia (or Crocodylia) are an order of mostly large, predatory, semiaquatic reptiles. They appeared 83.5 million years ago in the Late Cretaceous period (Campanian stage) and are the closest living relatives of birds, as the two groups are the only known survivors of the Archosauria. Members of the order’s total group, the clade Pseudosuchia, appeared about 250 million years ago in the Early Triassic period, and diversified during the Mesozoic era. The order Crocodilia includes the true crocodiles (family Crocodylidae), the alligators and caimans (family Alligatoridae), and the gharial and false gharial (family Gavialidae). Although the term ‘crocodiles’ is sometimes used to refer to all of these, a less ambiguous vernacular term for this group is crocodilians.

Large, solidly built, lizard-like reptiles, crocodilians have long flattened snouts, laterally compressed tails, and eyes, ears, and nostrils at the top of the head. They swim well and can move on land in a “high walk” and a “low walk”, while smaller species are even capable of galloping. Their skin is thick and covered in non-overlapping scales. They have conical, peg-like teeth and a powerful bite. They have a four-chambered heart and, somewhat like birds, a unidirectional looping system of airflow within the lungs, but like other non-avian reptiles they are ectotherms.
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Alligators, would you prefer fresh water, are a bit less dangerous to humans than crocodiles.

… alligators strongly preferring fresh water, while crocodiles can tolerate salt water due to specialized glands for filtering out salt. In general, crocodiles tend to be more dangerous to humans than alligators. 

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When did the alligator family diverge from true crocodiles?

According to one timeline I found, the American alligator dates from 150,000,000 BC to the present while the true crocodile family extends back to 50,000,000 years BC. Alligators seem to be 100 million years older than crocodiles, so I take this to mean that they diverged 50 million years ago.

Leave a comment and correct me if I’m wrong.

I like to imagine that that particular alligator knows it’s a costume, and is thinking, “Ah, I get it. T Rex evolved into these clothes wearing builder monkeys that feed me. Weird.”