What defines a synapsid?

What is the synapsid/sauropsid division of vertebrates?

The synapsid/sauropsid division supplemented another approach, one that split the reptiles into four subclasses based on the number and position of temporal fenestrae, openings in the sides of the skull behind the eyes.

Which of the following groups of animals are synapsids?

The primitive synapsids were known as pelycosaurs. The advanced mammal-like synapsids were known as therapsids. The synapsids which evolved from basal amniotes were known as sauropsids (includes modern reptiles and birds). So, the correct answer is ‘Pelycosaur, therapsids and mammals’.

What are the primitive synapsids called?

The primitive synapsids were known as pelycosaurs. The advanced mammal-like synapsids were known as therapsids. The synapsids which evolved from basal amniotes were known as sauropsids (includes modern reptiles and birds).

Is a reptile a mammal or a vertebrate?

Reptiles have characteristics of a Vertebrate: Reptiles have traits that are comparable to those of mammals, birds, and certain amphibians. The spinal cords that span the length of their bodies are housed in their backbones. From the tail to the skull, reptiles contain a chain of bone parts.

What is the difference between a synapsid and a sauropsid?

Although early synapsids have historically been referred to as “mammal-like reptiles,” all synapsids are more closely related to mammals than to any modern reptile. Sauropsids, on the other hand, include all amniotes more closely related to modern reptiles than to mammals.

Are synapsids reptiles?

Early synapsids used to be called ” mammal -like reptiles,” but this is a misnomer, as they were not reptiles at all. Synapsids and sauropsids split off from each other approximately 320 million years ago, during the late Carboniferous period.

What happened to synapsids after the Paleogene extinction?

After the Cretaceous–Paleogene extinction event, the mammalian synapsids diversified again to become the largest land and marine animals on Earth. At the turn of the 20th century synapsids were thought to be one of the four main subclasses of reptiles.

How did the sauropsid and synapsid lineages evolve?

According to Goodrich, both lineages evolved from an earlier stem group, the Protosauria (“first lizards”), which included some Paleozoic amphibians as well as early reptiles predating the sauropsid/synapsid split (and thus not true sauropsids).

Which of the following synapsids evolved from basal amniotes?

The synapsids which evolved from basal amniotes were known as sauropsids (includes modern reptiles and birds). So, the correct answer is ‘Pelycosaur, therapsids and mammals’. Was this answer helpful?

How did synapsids evolve?

Synapsids evolved from basal amniotes and are one of the two major groups of amniotes, the other being the sauropsids, the group that includes reptiles and birds. The distinctive temporal fenestra developed in the ancestral synapsid about 318 million years ago, during the Late Carboniferous period.

How did the early amniotes diverge into two lineages and three groups of reptiles?

by the middle of the carboniferous period the early amniotes had diverged into two lineages and three groups of reptiles” synapsids the lineage that gave rise to mammals

Are synapsid reptiles monophyletic?

Synapsid reptiles and the mammals that evolved from them form one monophyletic clade. There are two groups of synapsid reptiles, the pelycosaurs and the therapsids, the latter of which includes an advanced group known as the cynodonts.

What did early synapsids look like?

Early synapsids used to be called ” mammal -like reptiles,” but this is a misnomer, as they were not reptiles at all. Synapsids and sauropsids split off from each other approximately 320 million years ago, during the late Carboniferous period. Both looked like small lizards.

How did the extinction of Cretaceous lizards and snakes affect evolution?

The extinction of Cretaceous lizards and snakes may have led to the evolution of modern groups such as iguanas, monitor lizards, and boas. On land, giant boid and enormous madtsoiid snakes appeared, and in the seas, giant sea snakes evolved. Teleost fish diversified explosively, filling the niches left vacant by the extinction.

What happened to the synapsids after the Cretaceous extinction?

The cynodont group Probainognathia, which includes Mammaliaformes, were the only synapsids to survive beyond the Triassic. After the Cretaceous–Paleogene extinction event, the mammalian synapsids diversified again to become the largest land and marine animals on Earth.

What are the two groups of synapsid reptiles?

There are two groups of synapsid reptiles, the pelycosaurs and the therapsids, the latter of which includes an advanced group known as the cynodonts. From anapsid reptiles evolved two groups of higher reptiles: the synapsids (which would lead to mammals) and the diapsids (which would lead to crocodiles, pterosaurs, dinosaurs, and birds).

Which of the following is an example of a uricotelic animal?

Reptiles, Birds, Land Snails, Insects Uricotelic animals are those animals that excrete their waste matter in the form of uric acid. Reptiles, birds, land snails and insects are uricotelic animals. So the correct option is A.

What is an anapsid reptile?

These reptiles were small lizard like animals that apparently lived in forested habitats. They are the Eureptilia (true reptiles), and their presence during this suggests that they were distinct from a more primitive group, the anapsids (or Parareptilia).

What did the diapsids evolve into?

Finally, the diapsids evolved into the first archosaurs, which then split off into dinosaurs, pterosaurs, crocodiles, and (probably) marine reptiles like plesiosaurs and ichthyosaurs.

Why do mammals have synapsids?

Most mammals are viviparous and give birth to live young rather than laying eggs with the exception being the monotremes. To facilitate rapid digestion, these synapsids evolved mastication (chewing) and specialized teeth that aided chewing. Also, are lizards Synapsids?

What are the two types of synapsids?

The synapsids are traditionally divided into a primitive group and an advanced group, known respectively as pelycosaurs and therapsids. ‘Pelycosaurs’ make up the six most primitive families of synapsids. They were all rather lizard-like, with sprawling gait and possibly horny scutes.