What are diapsid reptiles?
Aside from turtles, diapsid reptiles comprise archosaurs, lepidosaurs, and their closest extinct relatives. In addition to the two temporal openings, diapsids also share the presence of a large opening in the bony palate, the suborbital fenestra ( Rieppel, 1993 ).
Did alligators live with Dinosaurs?
The geological eras in which the dinosaurs lived was the Mesozoic, ending in the C-T Extinction that happened in the Cretaceous period at the end of the Mesozoic. The ancestors of alligators survived the C-T Extinction and survived in the modern-day Cenozoic geological era. Did Alligators Live with Dinosaurs? Ancient Species of Alligator
What is the alligator’s body shape?
The alligator has a broad snout. It’s relatively wide throughout, creating a nice rounded tip. If you look at it from above, you’ll notice that the snout is U-shaped. Zoologists believe that the broader shape facilitates their preference for crushing objects. Tough targets like turtles are no match for the alligator!
How many species of diapsid animals are there?
At least 17,084 species of diapsid animals are extant: 9,159 birds, and 7,925 snakes, lizards, tuatara, turtles, and crocodiles. The name Diapsida means "two arches", and diapsids are traditionally classified based on their two ancestral skull openings ( temporal fenestrae) posteriorly above and below the eye.
See more
What are diapsids?
How many diapsids are there in the world?
What are the three subclasses of diapsids?
About this website
Are alligator skulls diapsid?
Diapsids ("two arches") are a group of amniote tetrapods that developed two holes (temporal fenestra) in each side of their skulls about 300 million years ago during the late Carboniferous period. The diapsids are extremely diverse, and include all crocodilians, lizards, snakes, tuatara, turtles, and birds.
Are crocodiles Synapsids or diapsids?
(c) Diapsid Skull: Perhaps the most famous diapsids are the dinosaurs, but diapsid also covers snakes, crocodiles, lizards and birds.
What animals have a diapsid skull?
Modern diapsids include lizards, snakes, turtles, birds, and crocodylians; extinct diapsids include dinosaurs, pterosaurs, ichthyosaurs, and many other familiar taxa. The stem-based name Diapsida is derived from the presence of a pair of fenestrae in the temporal region of the skull.
Are crocodiles diapsid?
The tuatara, crocodiles and squamates all belong to the subclass Diapsida. Crocodiles and the tuatara have a true diapsid skull with a dorsal and lateral opening.
Is a crocodile a synapsid?
Living reptiles such as snakes and crocodiles are characterised by a diapsid situation which is the presence of two openings in the skull, namely, the lower and the upper temporal fenestrae. The lower temporal fenestra of diapsids is the equivalent of the single fenestra of synapsids.
Are all reptiles diapsid?
ArchosaurNeodiapsi...DinosaurTuataraSauroptery...IchthyosaurDiapsid/Lower classifications
What reptiles have a diapsid skull?
Diapsids ("two arches") are a group of reptiles that developed two holes (temporal fenestra) in each side of their skulls, about 300 million years ago during the Late Carboniferous period. Living diapsids are extremely diverse, and include all crocodiles, lizards, snakes, and tuatara.
Is a dinosaur a diapsid?
Modern diapsids include lizards, snakes, turtles, birds, and crocodylians; extinct diapsids include dinosaurs, pterosaurs, ichthyosaurs, and many other familiar taxa. The stem-based name Diapsida is derived from the presence of a pair of fenestrae in the temporal region of the skull.
What is the meaning of diapsid?
Definition of diapsid : of, relating to, or including reptiles (such as the crocodiles) with two pairs of temporal openings in the skull.
Is a crocodile part of the dinosaur family?
Crocodiles This is what you came for: big, scary reptiles, right? Well, crocodiles share a heritage with dinosaurs as part of a group known as archosaurs (“ruling reptiles”), who date back to the Early Triassic period (250 million years ago).
What dinosaur did alligators evolve from?
archosaursAbout 250 million years ago, the archosaurs split into two groups: a bird-like group that evolved into dinosaurs, birds, and pterosaurs, and a crocodile-like group that includes the alligators and crocs alive today and a diversity of now-extinct relatives.
What was the first diapsid?
The evolutionary history of the diapsid lineage is quite complex; diapsids evolved into many shapes, occupying many different ecological niches since they first came onto the scene in the late Carboniferous Period (roughly 350 million years ago), when they were represented by the earliest diapsid, the tiny lizardlike ...
What is the difference between a Synapsid and an Diapsid?
Diapsid is a vertebrate that possesses two major holes known as temporal fenestrae in their skull while synapsid is a vertebrate that possesses only one hole in each side of their skull around the temporal bone. Most reptiles and all the birds are diapsids while most mammals are synapsids.
Diapsid - an overview | ScienceDirect Topics
The earliest known divergence yielded the araeoscelidians, a short-lived group, and the saurians (Fig. 1.11, Table 1.3).The araeoscelidians were small (about 40 cm total length) diapsids of the Late Carboniferous and were an evolutionary dead end.In contrast, the saurian lineage gave rise to all subsequent diapsid reptiles.
What is a diapsid?
Diapsida is a diverse clade of reptiles. Modern diapsids include lizards, snakes, turtles, birds, and crocodylians; extinct diapsids include dinosaurs, pterosaurs, ichthyosaurs, and many other familiar taxa. The stem-based name Diapsida is derived from the presence of a pair of fenestrae in the temporal region of the skull.
What is the difference between a turtle and a diapsid?
Turtles are anapsids, unmistakable due to the presence of a bony shell covering the body. Diapsids include the saurians (crocodilians and, according to many taxonomists, birds) and the lepidosaurians (tuataras, lizards, and snakes) (Zug, 1993 ).
What animals have a diapsid skull?
Within Diapsida a variety of specializations evolved. Among those that display a fully diapsid pattern are tuataras ( Sphenodon) and crocodylians. Birds, lizards, and snakes, however, have tended to lose one or both temporal bars. This has decoupled the posterior part of the skull, allowing the potential for considerable flexibility among the functional regions of the skull. In general, lizards have lost the lower temporal bar and snakes both the lower and upper temporal bars. At this point, we must elaborate on the presence of the classic diapsid condition in Sphenodon. We noted earlier that Sphenodon possesses the lower temporal bar. For many years, this condition was interpreted as the retention of an ancestral diapsid condition, and so Sphenodon was long designated as a living fossil. However, recent work has demonstrated that all lepidosaurs (rhynchocephalians and squamates) inherited a skull without a lower temporal bar; that is, it is the ancestral condition for this clade. The presence of the lower temporal bar in Sphenodon is thus due to secondary redevelopment of this structure, rather than to retention of the ancestral diapsid condition (see Mo et al., 2010). Birds have lost the upper temporal bar so the infratemporal and supratemporal fenestrae have merged into a single large opening. Further, they have lost the bony bar posterior to the orbit, merging the orbit and the fenestrae. Among synapsids, in mammals the fenestra increases in size and the bony bar behind the orbit generally disappeared so that orbit and fenestra merge. Although this resembles the condition in birds, the morphologies are convergent.
What subclass do crocodiles belong to?
The tuatara, crocodiles and squamates all belong to the subclass Diapsida . Crocodiles and the tuatara have a true diapsid skull with a dorsal and lateral opening. Lizards have only one dorsal opening while snakes have an even more modified diapsid skull, having completely lost the upper temporal arch between the two openings (Bellairs 1969b; Carroll 1979; Pough 1998f ). This has enabled the quadrate bone to move backwards and forwards in a condition called streptostyly.
How are turtles distinguished from other reptiles?
All other reptilian groups are united as Eureptilia. Turtles are easily distinguished from other reptiles by their bony shell ( Figure 5 ). The shell comprises a dorsal carapace and a ventral plastron, which are linked by a bony ‘bridge’ on either side ( Romer, 1956 ). Parts of the shoulder girdle and the ribs are integrated into the bony shell. The head, neck, and limbs can be withdrawn into the shell in most present-day turtles. Turtles lack true temporal openings although the back of the cranium is distinctly emarginated in many species ( Rieppel, 1993 ). Thus, most paleontologists assumed that turtles evolved from the earliest known reptiles ( Romer, 1956 ). However, recent discoveries have established that turtles evolved from early diapsid reptiles and some stem-turtles retained two temporal openings on either side of the cranium ( Schoch and Sues, 2015 ).
Where does the name Diapsida come from?
The stem-based name Diapsida is derived from the presence of a pair of fenestrae in the temporal region of the skull. These are secondarily closed in turtles. Diapsids are also diagnosed by a suborbital fenestra, an occipital condyle lacking an exoccipital component, and a ridged–grooved tibioastragalar joint.
Which group of dinosaurs were short lived?
The earliest known divergence yielded the araeoscelidians, a short-lived group, and the saurians ( Fig. 1.11, Table 1.3 ). The araeoscelidians were small (about 40 cm total length) diapsids of the Late Carboniferous and were an evolutionary dead end. In contrast, the saurian lineage gave rise to all subsequent diapsid reptiles. Members of the Sauria share over a dozen unique osteological features, including a reduced lacrimal with nasal–maxillary contact, no caniniform maxillary teeth, an interclavicle with distinct lateral processes, and a short, stout fifth metatarsal.
How are alligators related to dinosaurs?
They share common characteristics such as laying eggs, long hind legs, and short forelimbs and teeth that are set in sockets.
When did alligators evolve?
The earliest alligator ancestors evolved during the Triassic, then in the late Cretaceous, one fossil that was found to be an Alligatoroid was Brachychampsa. Brachychamsa evolved during the late-Cretaceous, and fossil remains have been found in Montana, USA, and Kazakhstan.
Which clade of Archosauria has a common ancestry of alligators?
Using Phylogenic cladograms, the common clade of Archosauria has clades of Pseudosuchia (common ancestry of alligators) and Orinthosuchia (common ancestry of dinosaurs and birds) – AdventureDinosaurs. The ancestral amniotes were divided into two main categories, Reptiles, and Synapsids. Reptiles were divided into three categories, ...
When did alligators and crocodiles evolve?
Several species of the order Crocodilia that include Crocodiles and Alligators of the modern-day evolved during the Mesozoic era. In terms of looks, the amazing thing is that modern-day alligators and crocodiles didn’t look too different from those of today.
When did alligators go extinct?
The first alligator species, now extinct, was Brachychampsa. They lived about 93.5 million years ago and went extinct 63 million years ago.
Which phylogenetic clade leads to dinosaurs and reptiles?
Here are the simplified versions of Phylogenetic clades for Vertebrata, which lead to dinosaurs and reptiles.
Is Spinosaurus related to alligators?
The Spinosaurus was related to alligators but there were some characteristics that are different. They also had similar ancestors – AdventureDinosaurs. TABLE – Similarities of Spinosaurus aegyptus Dinosaur vs. Alligator. In this table, we look at the similarities between a dinosaur and an alligator.
Why are birds considered diapsids?
Even the birds are considered diapsids (and hence reptiles), because they are descended from certain dinosaurs (which are also diapsids), and ancestrally have the paired skull openings along with other physical characteristics that unite them with diapsids. Thus, they are considered diapsids by their ancestry, which is illuminated by shared derived ...
When did diapsids first appear?
The evolutionary history of the diapsid lineage is quite complex; diapsids evolved into many shapes, occupying many different ecological niches since they first came onto the scene in the late Carboniferous period (roughly 350 million years ago), when they were represented by the earliest diapsid, the tiny lizardlike Petrolacosaurus.
What is the reptilia?
Or, if you consider yourself in the cladistic school of thought like most paleontologists, then if you say Reptilia, you are referring to all anapsids and diapsids (the usual snakes, lizards, crocodiles, and turtles, and their friends, including dinosaurs (and their descendants the birds)).
What is the name of the group of tetrapods?
You are actually quite familiar with the group of tetrapods known as diapsids, believe it or not. All members of the group called the Reptilia (see below), except for the anapsids (turtles and their ilk), and a few extinct groups, are diapsids. The main diagnostic physical character for a diapsid is the presence of two openings on each side ...
How are birds different from other living reptiles?
Birds are certainly quite different from other living Reptilia, but the traits that modern birds possess were acquired gradually over many million years of evolution. The first birds were quite different than modern birds, and looked much more like good traditional reptiles than hawks, doves, or turkeys do.
Is the term "reptile" valid?
The term "reptile" may carry a lot of psychological baggage with it , conjuring up outmoded images of slow, stupid, inferior creatures, but it is a valid term applied to the group comprising the first reptile and all of its descendants.
Is a champsosaur a diapsid?
Thus, they are considered diapsids by their ancestry, which is illuminated by shared derived traits. The skull of a champsosaur, an extinct diapsid related to the archos aurs. It is an example of convergent evolution with the crocodilians, as it is not directly related to them.
What are the characteristics of a crocodile?
Along with dinosaurs (including birds), croc odilians are derived from the archosaurs and distinguished from other reptiles by certain skull characteristics: openings in the skull in front of the eye, triangular rather than circular eye orbits, and laterally compressed teeth. Living crocodilians include the alligators, crocodiles, gavials, and caimans. Crocodilians have not changed much over their 170- million-year history. The snout is elongate and often used to capture food by a sideways sweep of the head. The nostrils are at the tip of the snout, so the animal can breathe while mostly submerged. Air passageways of the head lead to the rear of the mouth and throat, and a flap of tissue near the back of the tongue forms a watertight seal that allows breath ing without inhaling water in the mouth. A plate of bone, called the secondary palate, evolved in the archosaurs and separates the nasal and mouth passageways. The muscular, elongate, and laterally compressed tail is used for swimming, offensive and defensive maneuvers, and attacking prey. Teeth are used only for seizing prey. Food is swallowed whole, but if a prey item is too large, crocodilians tear it apart by holding onto a limb and rotating their bodies wildly until the prey is dismembered. Crocodilians swallow rocks and other objects as abrasives for breaking apart ingested food. Croco dilians are oviparous and display parental care of hatchlings that parallels that of birds. Nesting behavior and parental care may be traced back to the common ancestor of both groups.
What is the role of the amniotic egg in reptiles?
The Amniotic Egg. The amniotic egg provides a series of extraembryonic membranes that protect the embryo from desiccation. In reptiles, including birds, and one group of mammals, the egg is enclosed within a shell (not shown). The embryo develops at the surface of a mass of yolk. The amnion encloses the embryo in a fluid-filled sac and protects against shock and desiccation. The chorion is nearer the shell and becomes highly vascular and aids in gas exchange. The allantois is a ventral outgrowth of the gut and stores nitrogenous wastes (e.g., uric acid).
What are the two lines of amniotes?
Two lineages of amniotes diverged from reptiliomorph ancestors. One of these, Diapsida, gave rise to reptiles. This lineage includes the archosaurs (birds, crocodylians, and dinosaurs), turtles, and lepidosaurs (the tuatara, snakes, and lizards). The chameleon, Chamaeleo sp., is shown here.
What is the earliest lepidosaur?
Lepidosauria is a diapsid lineage that first appeared in the early Triassic. The earliest lepidosaurs were members of the Sphenodontia. They were widespread 200 to 100 million years ago. Now they are represented by a single genus that inhab its New Zealand. A second lepidosaur lineage is Squamata. These reptiles appeared in the middle Jurassic Period and, like the dinosaurs, underwent major extinctions 65 million years ago. Squamates that survived are the ancestors of today's liz ards and snakes. Lepidosaurs are characterized by the pres ence of overlapping, keratinized epidermal scales that are shed collectively. Detailed skeletal characteristics and tails that can undergo autotomy are also common features of this clade.
What is the phylogenetic relationship between amniotes and mammals?
Phylogenetic relationships within the amniotes are controversial. Strong molecular evidence suggests that the mammals (Synapsida) are closely related to ancestral amniotes. This lineage is shown using a clashed line. All other amniotes (Diapsida, including Aves) are a part of the reptillian linage, shown in solid lines. The traditional classification that excludes the birds from Reptilia is not valid because it results in paraphyletic groupings. In the interpretation shown here, the turtles are grouped with Diapsida. The absence of temporal fenestrae in their skulls must be a derived characteristic. Testudines is shown as a sister group to Archosauria, which is a subject of ongoing debate. Synapomorphies used to distinguish lower taxa are highly technical skeletal (usually skull) characteristics and are not shown. Daggers (t) indicate some extinct taxa. Other numerous extinct taxa are not shown.
Where Do Alligators Live?
Alligators inhabit swamplands, rivers, and lakes. They can’t tolerate high salt concentrations, so they tend to stay inland where water flow is pretty modest.
Where Do Crocodiles Live?
Crocodiles are far more prevalent around the world than alligators. While they tolerate a narrower band of temperatures, they live on many continents.
Do They Ever Share Habitats?
In most parts of the world, alligators and crocodiles do not cohabitate. Their lifestyles are different, and the same goes for their environmental requirements.
Alligator vs. Crocodile: Which Would Win In A Fight?
Here’s another question you hear pretty often. With two apex predators stacked against one another, it’s natural to think about who would win in a fight.
Which Is Faster?
The biggest strength that alligators have to bring to the table is speed. Gators are significantly faster and more agile compared to crocodiles.
Wrapping Up
Now that you have the full rundown when it comes to crocodiles vs. alligators, you’ll be able to appreciate each reptile a bit more. The differences between alligators and crocodiles are actually rather significant, with each creature making their own distinct mark on the animal kingdom.
What are diapsids?
Sauria. Diapsids ("two arches") are a group of amniote tetrapods that developed two holes ( temporal fenestra) in each side of their skulls about 300 million years ago during the late Carboniferous period. The diapsids are extremely diverse, and include all crocodilians, lizards, snakes, tuatara, turtles, and birds.
How many diapsids are there in the world?
At least 7,925 species of diapsid reptiles exist in environments around the world today (nearly 18,000 when birds are included).
What are the three subclasses of diapsids?
The other three subclasses were Synapsida (one opening low on the skull, for the "mammal-like reptiles"), Anapsida (no skull opening, including turtles and their relatives), and Euryapsida (one opening high on the skull, including many prehistoric marine reptiles). With the advent of phylogenetic nomenclature, this system of classification was heavily modified. Today, the synapsids are often not considered true reptiles, while Euryapsida were found to be an unnatural assemblage of diapsids that had lost one of their skull openings. Genetic studies and the discovery of the Triassic Pappochelys have shown that this is also the case in turtles, which are actually heavily modified diapsids. In phylogenetic systems, birds (descendants of traditional diapsid reptiles) are also considered to be members of this group.
