How are birds and crocodiles homologous?

How did crocodiles evolve differently from birds?

“The DNA in the modern-day crocodile has changed a lot less, versus the archosaur, than it has in birds,” said Haussler. By comparison, bird DNA took flight. Their pace of molecular evolution accelerated, and within about 15 million years of evolution, birds radiated out into the bulk of the existing 36 modern avian orders.

Is the DNA of a crocodile different from bird DNA?

“The DNA in the modern-day crocodile has changed a lot less, versus the archosaur, than it has in birds,” said Haussler. By comparison, bird DNA took flight.

What is the difference between dinosaurs and crocodiles and archosaurs?

– Before evolution acted upon crocodiles, they were mostly land animals. Their legs did not sprawl like those of today’s crocodiles, instead they stood with their legs tucked under their body like mammals and dinosaurs. – Archosaurs are reptiles that include birds, ancient crocodiles, and dinosaurs.

What did birds evolve from dinosaurs?

Birds evolved from a group of small bipedal dinosaurs. We find a number of animals that are gliders or fliers. Several kinds of reptiles and amphibians developed the ability to fly with horizontal ribs stretched into sails, or with a membrane between the ribs and hand.

How many species of birds were there before crocodiles?

For example, the true birds first appear in the fossil record many millions of years after the first crocodiles, yet today they number around 10,000 species, ranging from hummingbirds to ostriches. The crocodilians have only 25 species, and besides some variation in the shape of their skull they all look fairly similar.

Why do we use DNA to identify birds?

In the last twenty or so years, however, DNA has been used to clarify relationships among birds, as we do now with humans. Without getting too scientific, I’ll try to briefly explain the process without talking about the details of the chemistry involved.

Why study crocodile genomics?

The crocodilian genomes were also useful for the avian phylogenetic analyses, serving as a closely related “out group” for comparison with the bird genomes. Green and several other UC Santa Cruz researchers are coauthors of two articles on avian genomics that accompany the crocodile genomics paper in Science.

What is the difference between dinosaur and archosaur?

is that dinosaur is any of the creatures belonging to the clade dinosauria, especially those that existed during the triassic, jurassic and cretaceous periods and are now extinct while archosaur is (biology) any reptile of the taxon archosauria ; includes the extinct dinosaurs, plesiosaurs, pterosaurs and ichthyosaurs and the modern crocodiles.

Are dinosaurs closer to birds or reptiles?

Even though dinosaurs were reptiles, many palaeontologists believe that they’re closer to birds than they are to reptiles. Did crocodiles live with dinosaurs?

Are crocodiles related to dinosaurs?

Yes, actually. Both crocodiles and dinosaurs (including birds) are part of the clade called ‘archosauria’ — Ruling reptiles. Crocodiles branched away from the archosaur line that led to dinosaurs before pterosaurs and dinosaurs evolved.

What is the common ancestor of crocodiles and alligators?

Crocodylia is cladistically defined as the last common ancestor of Gavialis gangeticus (the gharial ), Alligator mississippiensis ( American alligator ), and Crocodylus rhombifer (the Cuban crocodile) and all of its descendents. The phylogenetic relationships of crocodilians has been the subject of debate and conflicting results.

Are crocodiles related to birds and dinosaurs?

Crocodilians are more closely related to birds and dinosaurs than to most animals classified as reptiles, the three families being included in the group Archosauria (‘ruling reptiles’).

How many different types of crocodiles are there?

Currently there are 23 different types of crocodile species have been identified and classified in the reptile order – Crocodilia. The American alligator is a giant crocodilian reptile endemic to the Southeastern United States. Living in the bodies of freshwater, the American alligator is slightly larger than the Chinese alligator.

When did crocodiles first appear?

They were followed by the mesosuchians, which diversified widely during the Jurassic and the Tertiary. Another group, the eusuchians, appeared in the late Cretaceous 80 million years ago and includes all the crocodilians living today.

How big is a bird’s genome?

The bird genome turned out to be slim as vertebrates go — about 1-1.26 billion base pairs, which are the molecules that join together to make the lattice of DNA’s double helix. Birds seem to have ditched a lot of DNA as they took flight, jettisoning the code for such things as teeth and a second ovary, the studies show.

How can DNA be used to identify a species?

In this case, other studies (if possible) such as barcoding (based on the assumption that particular gene sequences are varying in the sibling species) can help to identify species differences that are not visible morphologically. So DNA based studies can supplement morphological studies when it comes to describing species.

What can genome drafts from Crocodylia tell us about evolution?

Order Crocodylia is a key group within Reptilia and genome drafts from crocodilians would provide insights into ancestral reptilian and amniote genomes. These genome assemblies will also enable more detailed inferences on the evolution of three additional lineages of substantial interest to vertebrate biologists: dinosaurs, pterosaurs and birds.

What can we learn from avian and crocodilian genomes?

Avian and crocodilian genomes provide the best hope for elucidating the gene and genomic properties of dinosaurs and other extinct archosaurs, about which we have learned surprising amounts (for example, genome size and limited protein sequences) considering we have no access to the DNA of these organisms [ 15 – 19 ].

What is the International crocodilian genomes working group?

The International Crocodilian Genomes Working Group (ICGWG) will sequence and assemble the American alligator ( Alligator mississippiensis ), saltwater crocodile ( Crocodylus porosus) and Indian gharial ( Gavialis gangeticus) genomes. The status of these projects and our planned analyses are described.

What is the difference between dinosaur and reptiles?

Furthermore, dinosaurs stand up on their legs, positioning their bodies directly on the legs while reptiles have parallel thigh bones to the ground. Moreover, dinosaurs can run faster than other reptiles of the same size while reptiles walk and run with a side-to-side motion.