Lepidosauria is a subclass of reptiles, including Rhynchocephalia and Squamata. Scaled reptiles include lizards, snakes and amphisbaenian. Scaled reptiles contain more than 9,000 species and are therefore by far the most species-rich and diverse reptile order to date. The Rhynchocephalia order was a large and diverse group of reptiles in the Mesozoic era. However, it is represented by the only living species which is the Tuatara, a superficially lizard-like reptile which is native to the country New Zealand.
Highlights
Lepidosauria is a monophyletic group that includes all descendants of squamous cell carcinoma and the last common ancestor of the lymphatic cranial. Lepidosauria can be distinguished from other reptiles by several characteristics, such as large keratin scales that can overlap. In the context of purely modern taxa, lepidosauria can be considered a sister taxon of archosaurs, including aves (birds) and crocodiles. Testudines (turtles) may be associated with lepidosauria or archosaurs, but there is no consensus on this topic. Lepidosauria are included in the broader group of lepidosauromorpha, defined as all reptiles that are closer to lepidosauria than archosaurs.
Description of Lepidosauria
Existing reptiles are found in the clade diapsids, named after a pair of infratemporal windows on either side of the skull. Until recently, diapsids were said to consist of lepidosauria and their sister taxa, archosaurs. Subclass Lepidosauria are divided into Squamata and Tuatara. Recent morphological and molecular studies have also shown that turtles do not have temporary windows, but are firmly placed in diapsids.
Lepidosauria subclass reptiles can be distinguished from other reptiles by many characteristics. Initially, the male developed a hemipenis instead of the single erectile tissue penis found in crocodiles, mammals, birds and turtles. The hemipenis is at the base of the tail. Tuatara did not fully develop the hemipenis, but instead have a pair of flat ridges on the cloaca, which was determined to be the precursor of the hemipenis.
Lepidosaurs can automate their tails. However, in some modern species this feature has been lost. The lizard’s tail vertebrae have a fractured surface that allows the tailbone to be removed.
The scales of lepidosauria, unlike the scales found in other reptiles, have a keratinized (keratinized) structure of the epidermis and can be shed together. This happens in different cycles depending on the type. However, lizards generally fall off in flakes, and snakes fall off in one piece. Unlike lepidosauria, lepidosauria scales often overlap like roof tiles.
Defence mechanism
As their primary defence, most lepidosaurs rely on camouflage. Some have evolved to harmonize with their ecosystems, while others may change their skin color to harmonize with their current environment. Among lepidosaurs, the ability to automate the tail is another common defense. Other species, such as Echinosaurus, have evolved death simulation defenses.
Diet and hunting of Lepidosaurs
Lepidosauria subclasses include herbivores, omnivores, insectivores, and carnivores. Herbivores are composed of iguanas, some agama, and some lizards. Most species of lizards and some species of snakes are predators. The remaining species of snakes, the tuatara and the amphisbaenia, are carnivores. For example, some snake species are generalists, while others eat a limited range of prey, while salvadra eat only lizards. The rest of the lizards are omnivorous and can eat plants and insects. The broad carnivorous diet of tuatara can be facilitated by a special shearing mechanism with anterior movement of the mandible after the jaw is closed. Birds of prey, waders, street runners and other birds and mammals are known to prey on reptiles, but other reptiles are the main predators. Some reptiles eat reptile eggs. For example, Nile monitor food contains crocodile eggs, and small reptiles are hunted by large reptiles.