What is the Difference Between Dinosaurs and Reptiles

The main difference between dinosaurs and reptiles is that dinosaurs are a diverse group of extinct reptiles whereas reptiles include turtles, crocodilians, snakes, amphisbaenians, lizards, tuatara, and their extinct relatives. Furthermore, dinosaurs stand up on their legs, positioning their bodies directly on the legs while reptiles have parallel thigh bones to the ground. Moreover, dinosaurs can run faster than other reptiles of the same size while reptiles walk and run with a side-to-side motion.

Dinosaurs and reptiles are two forms of animals with a long evolutionary history. They are characterized by the presence of a scaly skin and laying eggs on the land. 

Key Areas Covered

1. Dinosaurs
     – Definition, Characteristics, Behavior
2. Reptiles
     – Definition, Characteristics, Behavior
3. What are the Similarities Between Dinosaurs and Reptiles
     – Outline of Common Features
4. What is the Difference Between Dinosaurs and Reptiles
     – Comparison of Key Differences

Key Terms

Avian Dinosaurs, Dinosaurs, Poikilotherms, Reptiles, Scaly Skin

Dinosaurs – Definition, Characteristics, Behavior

Dinosaurs or ‘terrible lizards’ were a diverse group of animals on the land, including varieties from gigantic long-necked sauropods to therapods like T-rex. The main types of dinosaurs are the ankylosaurians (armored herbivorous quadrupeds), stegosaurians (plated herbivorous quadrupeds), ceratopsians (herbivorous quadrupeds with horns and frills), ornithopods (bipedal or quadrupedal herbivores including “duck-bills”), theropods (mostly bipedal carnivores and birds), and sauropodomorphs (mostly large herbivorous quadrupeds with long necks and tails). Modern birds have evolved from theropods. Therefore, dinosaurs are divided into two main groups: avian dinosaurs and non-avian dinosaurs.

Figure 1: Dinosaurs Size

In addition, dinosaurs first appeared during the Triassic period between 243 and 233.23 Mya. After the Triassic–Jurassic extinction event 201 million years ago, they became the dominant terrestrial vertebrates on land and it continued through the Jurassic and Cretaceous periods. Moreover, dinosaurs were warm-blooded animals, who were either herbivores or carnivores. However, birds or the avian dinosaurs are the only group of dinosaurs to survive the Cretaceous–Paleogene extinction event 66 Mya.

Reptiles – Definition, Characteristics, Behavior

Reptiles are the tetrapod animals that belong to the class Reptilia. Some reptiles are limbless. Some reptiles live on the land while the others live in water. They undergo internal fertilization and lay eggs covered by a shell. One of the key features of reptiles to survive on the land is the presence of scaly skin. Some reptiles have an external bony plate, covering their body. Some examples of reptiles are turtles, crocodilians, snakes, amphisbaenians, lizards, tuatara, etc.

Figure 2: Reptiles

Moreover, reptiles are ectothermic or cold-blooded animals, who use external sources to heat up their body. Also, reptiles are poikilotherms whose body temperature vary, rather than remaining stable. They bask in sunny places to warm up and find shady places to cool down their body. Generally, reptiles have long lifespans as well. Some reptiles like tortoises can live for more than 150 years; alligators can live nearly 70 years.

Similarities Between Dinosaurs and Reptiles

• Dinosaurs and reptiles are two types of animals that lived in the Mesozoic Era – the ‘Age of Reptiles’.
• Both their skins are scaly.
• Also, both hatch from eggs.
• Moreover, they have four legs and a backbone.
• And, some of them have long necks and tails.

Difference Between Dinosaurs and Reptiles

Definition

Dinosaurs refer to any of a group Dinosauria of extinct, often very large chiefly terrestrial carnivorous or herbivorous reptiles of the Mesozoic era while reptiles refer to a vertebrate animal of a class distinguished by having dry scaly skin and typically laying soft-shelled eggs on land. Thus, this is the main difference between dinosaurs and reptiles.

Taxonomy

While dinosaurs belong to the clade Dinosauria, reptiles belong to the class Reptilia.

Classification

Dinosaurs encompass ankylosaurians, stegosaurians, ceratopsians, ornithopods, theropods, and sauropodomorphs while reptiles encompass turtles, crocodilians, snakes, amphisbaenians, lizards, and tuatara.

Origination

Moreover, dinosaurs first originated during the Triassic period, between 243 and 233.23 million years ago while reptiles first originated during the Carboniferous period around 312 million years ago.

Habitat

Also, another major difference between dinosaurs and reptiles is that dinosaurs lived on the land while reptiles live in both land and water.

Posture

Furthermore, one other difference between dinosaurs and reptiles is that most dinosaurs are bipeds with upright posture and some are quadrupedal while most reptiles are tetrapods and some do not develop limbs.

Hip Socket

Another difference between dinosaurs and reptiles is that dinosaurs have a hole in their hip socket, permitting upright stance, while reptiles do not develop a hole in the hip socket.

Thigh Bones

Besides, the thigh bones of dinosaurs are horizontal while the thigh bones of reptiles are parallel to the ground.

The proportion of the Lower Arm to the Upper Arm

Dinosaurs have significantly long lower arms when compared to their upper arms while reptiles have lower and upper arms in similar length. Hence, this is another difference between dinosaurs and reptiles.

Motion

Furthermore, dinosaurs can run faster than other reptiles of the same size while reptiles walk and run with a side-to-side motion.

Maintenance of Body Temperature

Dinosaurs are warm-blooded or partially warm-blooded while reptiles are cold-blooded animals.

Conclusion

Dinosaurs are an extinct group of reptiles who maintained an upright posture. The presence of a hole in their hip socket permits this posture. Therefore, they had longer lower limbs as well. In comparison, reptiles are a diverse group of animals that live in both land and water. They are mainly tetrapods. Dinosaurs are warm-blooded while reptiles are cold-blooded animals. Both dinosaurs and reptiles hatch eggs and have scaly skin. However, the main difference between dinosaurs and reptiles is their posture and the maintenance of body temperature.

References:

1. Chamary, J V. “Dinosaurs, Pterosaurs And Other Saurs — Big Differences.” Forbes, Forbes Magazine, 5 June 2015, Available Here.
2. “Characteristics of Reptiles|Biology for Majors II.” Lumen Learning, Lumen, Available Here.

Image Courtesy:

1. “Dinosaurs size” By Zachi Evenor (CC BY-SA 2.0) via Flickr
2. “Extant reptilia” By see respective profiles of photos – Compilation made by Petter Bøckman (CC BY-SA 3.0) via Commons Wikimedia