For those who still think the earth is only 6,000 years old. Why Birds Don't Have Teeth Live Science - ‎Dec 12, 2014‎ Birds - like anteaters, baleen whales and turtles - don't have teeth. But this wasn't always the case. The common ancestor of all living birds sported a set of pearly whites 116 million years ago, a new study finds. ExcerptBut no one knew exactly what happened to the teeth in the evolution of these animals from then until now. "The history of tooth loss in the ancestry of modern birds has remained elusive for more than 150 years," Springer said. [8 Foods for Healthy Teeth] In the new study, the researchers wondered whether the bird lineage lost its teeth in a single event, meaning the common ancestor of all birds did not have teeth, or whether edentulism happened independently, in different lines of birds throughout history, the researchers said. To find out, they investigated the genes that govern tooth production. In vertebrates, tooth formation involves six genes that are crucial for the formation of enamel (the hard tissue that coats teeth) and dentin (the calcified stuff underneath it). The researchers looked for mutations that might inactivate these six genes in the genomes of 48 bird species, which represent almost every order of living birds. A mutation in dentin- and enamel-related genes that was shared among bird species would indicate that their common ancestor had lost the ability to form teeth, the researchers said. They found that all of the bird species had the same mutations in dentin- and enamel-related genes. "The presence of several inactivating mutations that are shared by all 48 bird species suggests that the outer enamel covering of teeth was lost around 116 million years ago," Springer said. The researchers also found mutations in the in the enamel and dentin genes of other vertebrates that don't have teeth or enamel, including turtles, armadillos, sloths, aardvarks and pangolins, which look like scaly anteaters. The closest living modern reptile relative of birds is the alligator, Springer said. "All six genes are functional in the American alligator," Springer said. This tooth finding is one of many that came out of a large-scale scientific effort to study the evolution of birds. The findings of that effort were published today (Dec. 12) in the journal Science, and in several other journals. http://www.livescience.com/49109-bird-teeth-common-ancestor.html
Wonder if they lost their teeth before they developed gizzards, or after they developed gizzards? Birds have to swallow sand, so that gizzard muscle can grind up the seeds they eat, and cannot chew up. Wonder if all birds have gizzards? And why would a fish eating bird, even need one? Or the predator birds like hawks? I know chickens do, for my brother used to eat fried gizzards.
All birds have gizzards, but not all will swallow stones or grit. My theory on why birds don't have teeth is more in tune with the weight savings attributed to the heavy bones and muscles that back them up might be a drawback to a flying creature. Birds that had the genetic mutation for losing their teeth and developing beaks, were better suited for sustained flight because they were lighter in weight.
Alligators have both teeth and gizzards. - - - Updated - - - They do. - - - Updated - - - A gizzard is a muscular part of the digestive system, usually in between the esophagus and the stomach in birds and alligators (and maybe other critters). Some birds and alligators swallow stones/sand that ends up staying in the gizzard to help them break food down.
And here I thought they'd just got into a disagreement with Billy Bob Rex down at the Jurassic Bar and Grill. How do Sharks figure in here? (If they do) I've heard that sharks are much older than birds and also that their teeth are much different than mammals, being made of the same sort of armor like substance forming the skin that convers their bodies.
Sharks are far older than birds and adapted long ago to an aquatic environment rather than terrestrial. The teeth are indeed different than mammalian...but they also vary greatly within the shark family.
A problem persists that beaks are believed to be some finger nail like piece of inert substance without appreciation for their qualities as a sensory organ loaded with all kinds of sensory receptors. Pressure. Smell/Taste. Who knows what else. Moi r > g No
birds descended from dinosaurs, first dinosaur was about 230 million ago, first sharks 420 million years ago....off topic but still interesting, sharks aren't even fish...
bats do fine with teeth as did many giant extinct flying reptiles ...weight probably factors in but probably not the only reason...
All of you are over thinking this. They don't have teeth because they have no way of brushing them as they also don't have hands.
Well, most biologists I know classify sharks as fish. This includes ichthyologists. Shark's teeth aren't that much different than mammals. They have the same basic structure. Their skin has dentine in the scales, just like we have dentine in our teeth. The scales are very similar to small teeth.
Outstanding! I learned something. Had no clue alligators had them as well. This is a link between reptiles and birds, which we already knew was there, but good info. One wonders if some dinos, tasted like chicken? LOL
no they don't it's a misnomer they don't bother correcting... a shark is no more a fish than a starfish is...because it has gills an swims doesn't make it a fish anymore than a reptile living on land and has lungs makes it a mammal...sharks aren't fish..
I have a degree in biology, specializing in ichthyology (i.e. the study of fishes). A shark is a fish. Your example was totally insane. A starfish is an echinoderm, nothing at all like a fish. Basically speaking, fish means all vertebrates that aren't in Tetrapoda. There are three major groups of fishes: jawless fish, cartilaginous fish and bony fish. Sharks are cartilaginous fish. That said, classification above the species level can often be controversial and is a matter of opinion.
my example was one of a misnomer...the names we traditionally call things often don't reflect what they are and they're incorrectly given an incorrect name...when I was young many people still thought whales were fish, in some languages their popular names still reflect that, do we correct the error or perpetuate it ...just because you can stick "fish" on the end of the classification doesn't make it so, they may have a common ancestor but they are not the same... right, then birds and reptiles are mammals because it's just matter of opinion?...maybe birds, reptiles, amphibians and mammals are all fish too because all are vertebrates...
Are you sure that sharks adapted to an aquatic environment rather than a terrestrial one? Seems that since everything is supposed to have come from a pool of life containing water, the land animals would have evolved to life on land rather than the other way around.... I'd say that since the gizzard is also common in some fish, the gizzard in birds would have to be an appendage that just stayed with them once they evolved from being fish of the waters of life....
the 420 yr fossil history of sharks indicates they were always aquatic.. something like a gizzard could develop more than once...evidence would suggest our eyes developed independently from that of the squid...
