How to Make a Mammal in Nine Evolutionary Steps

Riley Black

Science Correspondent

Let’s take a fascinating journey through the evolution of mammals. From the earliest synapsids to modern-day species, mammals have undergone significant changes over millions of years. Here are nine evolutionary shifts that have shaped the mammals we know today.

1. A toolkit of teeth

Mammals have a diverse set of teeth that allow them to handle various types of food. From nipping to crushing, mammal teeth are specialized for different tasks. This dental diversity dates back to early synapsids like Dimetrodon, setting the stage for the evolution of mammalian teeth into the specialized forms we see today.

2. Long lost ribs

Early synapsids like Ophiacodon had belly ribs that offered protection but were eventually lost as synapsids evolved. This loss allowed for more upright postures, increased flexibility, and improved efficiency in movement.

3. A new roof in the mouth

Synapsids evolved a secondary palate, separating the nose from the mouth and throat. This adaptation allowed for efficient breathing while eating, enhancing the hunting and feeding abilities of early synapsids.

4. An earful of jaw

Early synapsids had complex jaw structures that evolved into a single bone in mammals, enhancing bite strength and improving hearing abilities. This shift in jaw structure allowed mammals to develop sensitive ears for navigating their environment.

5. Fur and whiskers

Early synapsids likely evolved fur and whiskers around 240 million years ago, aiding in insulation and sensory perception. This adaptation allowed mammals to thrive in various environments and become more nocturnal as they evolved.

6. Eye bones disappeared

Early synapsids had scleral rings in their eyes, a feature lost as mammals evolved. This shift allowed for greater flexibility and adaptation to different environments, contributing to the success of mammals in diverse habitats.

7. Walking postures shifted

Early synapsids had a low-slung body posture, but as mammals evolved, they transitioned to more upright postures. This shift allowed for increased speed, efficiency in movement, and improved foraging abilities, setting the stage for modern mammalian locomotion.

8. Milk fueled mammal growth

Mammals produce milk to nourish their young, a unique characteristic that sets them apart from other animals. The evolution of milk production allowed for faster growth and development of offspring, contributing to the success and diversity of mammalian species.

Main image credit: Illustration by Emily Lankiewicz /  Dmitry Bogdanov via Wikipedia under CC By-SA 3.0 / ДиБгд at Russian Wikipedia / Public Domain  / ДиБгд via Wikipedia under CC By-SA 4.0 / FunkMonk (Michael B. H.) via Wikipedia under CC By-SA 3.0 / Public Domain