Are Alligators Dinosaurs?
Alligators are not dinosaurs, but they, along with the other crocodilians, are the closest living relatives of dinosaurs (apart from birds, which are dinosaurs). Although alligators are neither dinosaurs, nor the descendants of dinosaurs, they are more closely-related to dinosaurs (and therefore birds) than they are to other living groups of reptiles, such as snakes and turtles.
To understand why alligators are not dinosaurs, and how the two groups of animals are related, we need to go back millions of years in the reptile family tree to the Mesozoic Era…
We’ll also need to find out a little more about alligators…
What Are Alligators?
One of two extant species of alligators, the American alligator (Alligator mississippiensis)
The American alligator (Alligator mississippiensis) and the Chinese alligator (Alligator sinensis) are the only two living species of alligators.
Many additional extinct alligator species have been discovered through fossils.
Alligators Are Crocodilians
Crocodilians are a kind of reptile that includes alligators. Crocodiles, caimans, and gharials are all found in this group.
Crocodilians have lengthy bodies and tails, short legs, and long, tooth-filled snouts. They are all carnivorous semi-aquatic animals.
Crocodilians, like all ambush predators, wait beneath the water for unsuspecting victims to be grabbed in their strong jaws.
A crocodilian’s eyes and nostrils are located on the top of its skull. Since the rest of its body is submerged underwater, it may observe and breathe.
Crocodilians are truly ancient, with crocododylomorphs (early crocodilians) living over 200 Mya during the Triassic Period.
Those early crocs would have looked a lot like current crocodiles in terms of both behavior and appearance.
How Are Alligators Related To Dinosaurs?
Alligators and dinosaurs are both reptiles, despite the fact that they aren’t dinosaurs.
Reptiles (animals with backbones) first arose over 300 million years ago and are a significant group of vertebrates.
The Archosauria reptile group also includes crocodilians (including alligators) and dinosaurs.
Archosaurs are reptiles that belong to the Archosauria family. Archosauria refers to “ruling reptiles.”
During the Mesozoic Era, which started about 252 million years ago, archosaurs were the dominant land creatures.
The only extant archosaurs are crocodilians (including alligators) and birds (which evolved from dinosaurs).
The Mesozoic Era
Because reptiles dominated the earth, the sea, and for much of the time, the air during the Mesozoic Era (known as “the Age of Reptiles”), it is known as “the Age of Reptiles.”
Mammalian species first appeared during the Mesozoic Period, however they were mostly tiny, nocturnal creatures.
There are three periods in the Mesozoic Era. The Triassic Period, which started around 252 million years ago, was the first of these. The Jurassic Period, which started at 201.3 million years ago, followed this. The Cretaceous Period, which started 145 million years ago, was the third and last period of the Mesozoic Era.
The Cretaceous–Paleogene extinction event, which occurred around 66 Mya, marked the end of the Cretaceous Period (and the entire Mesozoic Era). An asteroid impact (but that’s another tale) was thought to have triggered this.
Alligators And Dinosaurs Are Both Archosaurs
Both of these animals are archosaurs. The alligator is a pseudosuchian; the dinosaur an avemetatarsalian.
During the Mesozoic Era, the reptile group Archosauria was particularly successful.
Alligators and dinosaurs are both archosaurs, as we’ve discovered. The earliest Archosaurs (and their forerunners, the Archosauromorphs) emerged millions of years before the start of the Triassic Period.
Archosauria divided into two major groups during the Triassic: Pseudosuchia and Avemetatarsalia. Crocodilians would eventually develop from some pseudosuchians, while dinosaurs would develop from others.
Because of this, an archosaur that was the progenitor of alligators and dinosaurs existed at some point in the Triassic Period.
To put it another way, alligators and dinosaurs have a common progenitor; if you go back far enough in the family trees of both dinosaurs and alligators, you’ll wind up with the same archosaur that lived during the beginning of the Triassic Period.
Archosaurs had split off from other reptile groups, including snakes, lizards, and turtles, long before the Pseudosuchia / Avemetatarsalia divide.
As a result, all archosaurs, including crocodilians like alligators and dinosaurs (and consequently birds), are more closely related to one another than they are to other reptiles.
- The progenitor of both alligators and dinosaurs was Archosauria, a group of reptiles.
- Today’s alligators (and other crocodilians), as well as their forefathers, and all other archosaurs more closely related to crocodilians than to dinosaurs are members of the Pseudosuchia group of archosaurs.
- Avemetatarsalia includes dinosaurs as well as all other archosaurs more closely related to birds than to crocodilians.
Avemetatarsalians might also give rise to pterosaurs.
Dinosaurs Vs Crocodiles
The Triassic Period saw the first emergence of dinosaurs, which were a highly successful branch of archosaurs.
It’s perhaps surprising that, during the Triassic Period, it was those other archosaurs, the pseudosuchians, who were the apex predators, given their fearsome reputation.
During the Jurassic Period, the tables would be turned.
A massive extinction (known as the Triassic–Jurassic extinction event) occurred at the end of the Triassic Period, killing off all but the Crocodylomorphs, which were ancestors of today’s crocodilians.
The main theories for the mass extinction include massive volcanic eruptions, an asteroid strike, or enormous environmental changes. The precise reason for it is unknown.
It’s important to note that the Cretaceous-Paleogene extinction event, which wiped out the dinosaurs, occurred millions of years before the Triassic-Jurassic extinction event.
Dinosaurs were able to take over as the dominant land creatures in the Jurassic Period once their major competitors had vanished. Their reign raged until the conclusion of the Cretaceous Age, when they evolved into a variety of terrestrial niches.
Dinosaurs Become Birds
This hummingbird is a prehistoric creature, yes! The only surviving dinosaurs are birds.
A group of dinosaurs started to transform into birds sometime during the Jurassic Period.
As a result, many scientists believe that all birds are dinosaurs (sometimes known as “avian dinosaurs”) and use the term “dinosaurs” to refer to them.
As a result, many scientists believe that all birds are dinosaurs (sometimes referred to as “avian dinosaurs”) and use the term “bird dinosaurs” to differentiate them from true prehistoric reptiles.
An asteroid impact was most likely responsible for this global extinction, or at least started it.
By the beginning of the Cenozoic Era, the time of the dinosaurs, at least non-avian dinosaurs, was over whatever the exact cause of their mass extinction.
Crocodilians Survive The Cretaceous-Paleogene Extinction Event
During the Late Cretaceous, real crocodilians evolved from crocodylomorphs.
During the Cretaceous-Paleogene extinction event, crocodilians were one of the largest air-breathing creatures to survive. Their aquatic upbringing, ability to forage for food, and capacity to aestivate (enter a dormant mode akin to hibernation) may all play a role in this.
Crocodilians would, however, be limited to aquatic habitats throughout the Cenozoic. The mammals would take control on land.
Conclusion: Are Alligators Dinosaurs?
Alligators and other crocodilians aren’t dinosaurs, such as crocodiles and caimans. Crocodilians (including alligators) do not directly derive from dinosaurs.
Alligators (and other crocodilians, such as crocodiles and caimans) are the closest living (non-avian) relatives of dinosaurs since they are both archosaurs.
Most scientists now believe that birds are dinosaurs. Birds and crocodilians are more closely related to each other than they are to any other living reptiles because they share a common ancestor (dinosauroids, including birds).