Well, let me start by saying that lizards are a fascinating group of animals. I have always been intrigued by their scaly bodies, quick movements, and ability to adapt to a wide range of environments. So, when it comes to the question of what lizards evolved from, I find myself quite excited to delve into the topic.
To understand the origins of lizards, we need to go back in time, way back to the Mesozoic Era, specifically the Triassic period, which spanned from about 252 to 201 million years ago. It was during this time that the first reptiles appeared on Earth, and it is from this group that lizards ultimately evolved.
Within the reptilian order Squamata, which includes lizards and snakes, there are two major groups: the Iguania and the Scleroglossa. The Iguania group consists of iguanas, chameleons, and their relatives, while the Scleroglossa group contains all other lizards and snakes.
Now, let’s focus on the Scleroglossa group, as this is where the true origin of lizards lies. Within the Scleroglossa, there are two main lineages: the Anguimorpha and the Gekkota. The Anguimorpha lineage includes monitor lizards, alligator lizards, and legless lizards, while the Gekkota lineage consists of geckos.
Interestingly, fossil evidence suggests that the Anguimorpha lineage split from the Gekkota lineage during the Jurassic period, around 170 million years ago. This split marked the divergence of two distinct groups of lizards, each with its own unique characteristics and adaptations.
But where did these early lizards come from? Well, the answer lies in a group of reptiles known as the diapsids. Diapsids were a diverse group of reptiles that roamed the Earth during the late Permian and early Triassic periods, roughly 290 to 240 million years ago.
One particular diapsid, known as Megachirella wachtleri, is of particular importance in understanding the origins of lizards. Megachirella, which was discovered in northern Italy, is considered the oldest-known species of the Squamata order, making it an ancestor of all lizards and snakes we see today.
The discovery of Megachirella in the early 2000s shed light on the evolution of lizards, as its fossilized remains date back to around 240 million years ago. This means that lizards have been around for a remarkably long time, evolving and diversifying over millions of years to give rise to the incredible diversity of species we see today.
Lizards evolved from a group of reptiles known as diapsids, with the earliest known ancestor being Megachirella wachtleri. Through millions of years of evolution, lizards have adapted and diversified, giving rise to the vast array of species that inhabit our planet today. It’s truly remarkable to think about how these scaly creatures have persisted and thrived for so long, and I can’t help but be in awe of their evolutionary journey.