Dinosaur Dreaming

Common questions:
Mammal-like reptiles

Answers to school children's questions about the world and lives of a range of ancient reptiles that gave rise to the mammals.

What are the bones that stick out of the moose-like animal? (Estemmenosuchus)

The horns that stick out of the skull of the moose-like mammal-like reptile were probably for protection for its eyes and other delicate areas on its head when it was fighting with other mammal-like reptiles.

How are mammal-like reptiles similar to mammals?

Mammal-like reptiles share many characteristics of mammals. They have a similar skull to mammals in that they have a single hole in the side of the skull behind the eye socket. This puts them in a common group of animals called the Synapsids. Their teeth are differentiated into molars, canines, and incisors, similar to mammal's teeth. Their legs are directly beneath their body, unlike reptiles whose limbs are sprawled out to the side of the body.

What caused the ice caps to disappear?

The Ice caps disappeared after the great glaciation of the Late Carboniferous and Early Permian, about 300 million years ago.

Did some dinosaurs or mammal like reptiles have bone marrow or were all the bones hollow?

Some dinosaurs had hollow bones like birds, but all mammal-like reptiles had bones with marrow cavities.

How can the scientists judge (tell) accurately the size of the mammal-like reptile was? When something dies it shrinks!

When an animal dies, its bones do not shrink, therefore scientists can tell how big the animal would have been by comparing the size of its bones with other animals' bones.

When and where was the mammal-like reptile found?

Mammal-like reptile bones have been found in many countries, such as South Africa, Russia, France, and North America. But so far, none have been found in Australia.

How many bones are there in the mammal-like reptile, is it the same as a dinosaur?

There are over 200 bones in the skeleton of a mammal-like reptile, which is about the same number found in a dinosaur or a mammal, depending on the species.

How do you know the time in history these animals lived?

We know the time when these animals lived by dating the rocks their bones are found in. There are a number of different methods of dating the rocks and we usually use more than one method so we can be sure it is right.

Did these animals die out because they didn't have fur, during the cold?

We don't know why the animals eventually died out, but we don't think it was because of the cold alone. It was more likely a different change in the environment that they couldn't cope with that led to their extinction.

What was the first backboned mammal?

All mammals have backbones, and the earliest mammals were probably evolved from therapsid (mammal-like) reptiles and appear in the fossil record in the Triassic period.

What is the biggest reptile you have dug up?

The biggest parareptile we have dug up is a pareiasaur from Russia. It is about as big as a cow and is about 250 million years old. Its scientific name is Deltavyatka vyatkensis.

Did the planet have lots of active volcanoes when the mammal-like reptiles existed?

There were lots of volcanoes in Siberia at the end of the time when the mammal-like reptiles lived.

What was the average temperature during the day?

The average day temperature during this time was warmer than it is now.

How long did it take for the continents to split apart?

Continents move very slowly, at speeds of between 1 centimetre per year and 10 centimetres per year. This is about the same rate your fingernails grow at!

How many reptile (mammals) are there?

There are lots of mammal-like reptiles with more fossil species being discovered every year. There are 53 Families of Mammal-Like Reptiles, each family has at least one species, with some having as many as 100 species!

Were all the countries joined together?

There have been a number of times in the past when continents have been joined together. (Try cutting out maps of South America and South Africa and seeing if you can fit them together side by side!) The main time when all of these continents were together was about 250 million years ago, during the Permian.

How did reptile mammals get their name?

Mammal-Like Reptiles got their name because they have some features that make them like mammals, and some that make them like reptiles. They have mammal-like skulls and teeth, and they have reptilian-like ways of walking. Individual species are named after something they look like, the person who discovered them, or the place they were found in.

Are we going to continue to evolve, like how the mammals changed to dinosaurs, and then back to mammals?

All animal species (and we are animals after all!) are evolving all the time. However, mammals and dinosaurs are two separate groups. They have a common ancestor back in the late Devonian (about 350 million years ago) but they haven't evolved into each other.

Do the holes in the neck of the dinosaur's or the mammal's head have to do with their brain power?

The holes on the back of the heads of dinosaurs and mammal-like reptiles are to allow the attachment of muscles from the jaw (try touching your temple and closing your jaw to feel these muscles working). The bigger the holes are the stronger the bite is.

Are there any other main differences between the moose like creature and a modern moose?

The moose-like mammal-like reptile Estemmenosuchus is not related to the modern moose, but it may have used the bumps and horns on its head for similar purposes. Try looking up library books about moose to see what they use their horns and bumps for.

How long did it take for dinosaurs to take over from mammal-like reptiles?

The dinosaurs took about 20 million years to take over from the mammal-like reptiles, from about 220 million years ago to 200 million years for the transition to be complete and for dinosaurs to rule the earth!

What made the mammals that were alive before dinosaurs extinct?

The mammals that were around before the dinosaurs probably died out as a result of a major change in climate as the earth got warmer. This time was a period when more than 70-90% of all living species went extinct because they couldn't adapt as fast as the climate was changing.

What are some of the names of mammal-like reptiles?

Mammal-like reptiles are split into two groups, the Pelycosaurs and the Therapsids. Some of the names are: Dicynodont, Lystrosaurus, Estemmenosuchus (the one with the moose-like skull), and Sphenacodont.

Are there any animals similar to the mammal-like reptiles left?

The modern animal most like the mammal-like reptiles is the Platypus.

What was the first mammal-like reptile discovered and where did they find it?

The first mammal-like reptile discovered was in the 1700s in Central Russia, east of the Ural mountains (try finding these in an atlas). It wasn't recognised as a fossil or mammal-like reptile until much later, and is a therapsid.

Why was there such a change from primitive mammal-like reptiles to the dinosaur and how long do they think it took?

The mammals that were around before the dinosaurs probably died out as a result of a major change in climate as the earth got warmer. This time was a period when more than 70-90% of all living species went extinct because they couldn't adapt as fast as the climate was changing. The dinosaurs took about 20 million years to take over from the mammal-like reptiles, from about 220 million years ago to 200 million years for the transition to be complete and for dinosaurs to rule the earth!

What type of skin did the mammal-like reptiles have?

No skin impressions have been found from mammal-like reptiles yet, so we don't really know if they had hair or scales.

How many years ago did they exist before the dinosaurs?

The mammal-like reptiles first appear about 80 million years before the first dinosaur does. The are first around in the late Carboniferous, about 300 million years ago, while the first dinosaur appears about the mid Triassic, about 220 million years ago.

How many species of mammal-like reptiles were there?

There are lots of mammal-like reptiles with more fossil species being discovered every year. There are 53 Families of Mammal-Like Reptiles, each family has at least one species, with some having as many as 100 species!

When did the change from reptile to mammal occur?

The change from reptile to mammal probably occurred about the middle Permian, about 270 million years ago.

Is there a difference between male and female mouth structure?

We are not sure yet if there is any difference between male and female teeth in mammal-like reptiles, but the more fossils we find the closer we are to solving that problem. We know that some of them had tusks, but we don't know if these were females or males!

How do mammal-like reptiles reproduce - are they born living, or born in eggs?

It is most likely that mammal-like reptiles reproduced by laying eggs, as primitive mammals alive today, like the platypus, lay eggs. When we find some mammal-like reptile eggs we will know for sure!

What were the first mammals?

The first true mammals appeared in the mid Triassic about 200 million years ago. They were the Morganucodontids.

How did mammals lose power to dinosaurs?

The mammals that were around before the dinosaurs probably died out as a result of a major change in climate as the earth got warmer. This time was a period when more than 70-90% of all living species went extinct because they couldn't adapt as fast as the climate was changing. The dinosaurs took about 20 million years to take over from the mammal-like reptiles, from about 220 million years ago to 200 million years for the transition to be complete and for dinosaurs to rule the earth!

How did the mammal-like reptiles finally form into reptiles?

Some mammal-like reptiles evolved into mammals, others went extinct. None became reptiles.

Did the mammal-like reptiles live longer than the dinosaurs and why/why not?

The mammal-like reptiles were around for about 120 million years, while the dinosaurs were around for 180 million years. The climate began to get warmer, which favoured the dinosaurs while not being as good for the mammal-like reptiles.

What kind of temperature did the mammal-like reptiles live in?

The average day temperature during the time of the mammal-like reptiles was warmer than it is now.

What kind of food did they eat?

Mammal-like reptiles ate many different food types. Some were herbivores, some were carnivores, while others were omnivores, like us!

Can you tell how long one mammal-like reptile lived?

We're not really sure how long one mammal-like reptile lived. It is likely that they live about as long as animals like cows or deer live today, up to about 20 years.

Did the mammal-like reptiles breed with the dinosaurs?

The mammal-like reptiles did not breed with the dinosaurs. All groups of animals only breed with their own types.

What was the biggest mammal-like reptile?

The biggest mammal-like reptile was probably a large herbivore found from South Africa, like Moschops.

Would the plants that the herbivores ate still be around today?

Some of the plants that early herbivores ate are still around today, like conifers (pines) and Ginkgoes and ferns. Most of the trees and plants around today, the flowering plants, were not around during the times that mammal-like reptiles lived.

Which country has found the most mammal-like reptiles?

South Africa has so far found the most mammal-like reptiles, but Russia is a close second.

Do mammal-like reptiles have their own time periods like dinosaurs?

The period that the mammal-like reptiles were most common is the Permian, from about 280 million years ago to 250 million years ago.

How do you tell by the bones how the mammal-like dinosaurs [reptiles] live?

We can tell more about how mammal-like reptiles lived by the shape of their bones and the length of them. Long bones are usually from fast runners, while short bones are usually from slow movers.

How do you know whether the mammals had fur, hair, or scales?

We can tell the skin of some extinct animals if we find impressions on rock of their skins. We have not yet found any skin impressions for mammal-like reptiles so we are not sure what their skin looked like. Modern mammals have fur or hair, modern reptiles have scales.

If the mammal-like reptiles evolved before the dinosaurs what advantage did the dinosaurs have to take over?

The mammal-like reptiles were around for about 120 million years, while the dinosaurs were around for 180 million years. The climate began to get warmer, which favoured the dinosaurs while not being as good for the mammal-like reptiles.

How long have they been finding mammals in Australia and Victoria?

Fossil mammals have been found in Australia and Victoria since the first geological surveys were undertaken in the 1820s, but the aboriginal people of Central Australia knew of them long before this, they called them the Kadimakara, and thought they had fallen from the great sky land.

Do they think people have formed from the mammal-like reptiles?

People are mammals, and mammals evolved from mammal-like reptiles over the past 220 million years.

How do they know what the animals looked like?

We can tell what the animals looked like by carefully studying their bones and reconstructing where their muscles would go, and then putting skin and fur over the muscles.

How big are mammal-like reptile eggs?

We haven't found any mammal-like reptile eggs yet, so we don't know how big they would have been. We are still looking!