Were T. Rex and Velociraptor toothless?
This genetic study confirms those creatures were NOT the ancestor of modern birds.
Was T. Rex toothless?
". . . A new study suggests that the common ancestor of all living birds lost the ability to produce teeth, and the answer to exactly how this happened can be found in modern-day birds' genes.
For the study, the researchers examined the genomes of 48 living bird species, taking a close look at six genes associated with tooth formation.
What did they find? It turns out that all of the bird species share genetic mutations that inactivate genes involved in the formation of both tooth enamel and the portion of the tooth called dentin.
Based on the mutations, the researchers think that a common ancestor of the birds lost the enamel caps on its teeth around 116 million years ago. And around that same time, birds' beaks came into play.
“We propose that this progression ultimately resulted in a complete horny beak that effectively replaced the teeth and may have contributed to the diversification of living birds," study co-author Dr. Mark Springer, a biology professor at the University of California, Riverside, said in a written statement.
(Source: Birds Lost Teeth 116 Million Years Ago)
This event took place, 116 Million Years Ago?
Interesting. Especially since Velociraptor and T. Rex lived long after 116 Million Years ago.
Perhaps Velociraptor was this toothless ancestor?!
Oh *Snap!* no, Velociraptor wasn't toothless either.
So obviously, based upon the conclusions of the study, these creatures are not the ancestor of birds. And since we know true birds existed 165 Million years ago in the Jurassic, namely Archaeopteryx who was a toothed bird followed by many other species of toothed birds, it can be concluded an actual bird gave rise to modern birds and not Cretaceous theropod dinosaurs.
See also, Brush Your Beak: 10 Amazing Birds With Teeth.
So like yeah . . . any way . . . that sort of closes the case of whether or not T. Rex "evolved into chickens".
Subject: Re: Genetic Evidence at last (Bird vs. Cretaceous Theropod Dinosaur)
Date: Fri, 13 Nov 2015 21:25:30 +0000
From: Feduccia, John ABut---almost all the enantiornithines, dominant landbirds of the Mesozoic, were fully toothed, as well as the late Cretaceous ornithurines, the hesperornithids and ichthyornitds.
Great information, thanks!
Do you have alternative views as to what may have caused modern beaks to evolve the loss of teeth as they have?
Certainly, there's no doubt that such early toothed bird species should co-exist along with birds who evolved modern (toothlessness /loss of enamel/dentin in their) beaks/bills, i.e., such as Ichthyornis (135-70 mya ... like all the many ancient relatives of birds who were not direct common ancestors they went too went extinct (from the time frame you mention, Mesozoic [252-66 million years ago]).
The researchers set the approximate date for the emergence of the common ancestor who evolved genes for "toothlessness" to around 116 million years ago. That's drawing close toward the end of the Mesozoic, approximately Middle Cretaceous.
Naturally, toothed birds should continue to co-exist in the same time frame but eventually became extinct. Some have suggested that this adaptation (loss of teeth, or at least the loss of dentin / enamel) better suited birds to their food supply, i.e., capturing small minnows or consumption of berries. Interestingly, many birds retain some traits which clearly indicate they still possess genes to produce "pseudo-teeth" of sorts...the loss wasn't complete. Last night I was looking at photos of birds and the Canadian Goose' "Pseudo-teeth" are intimidating and look like teeth... I've read that some of the adaptations are more effective than teeth for grasping and holding on to prey / gathering food.
Brush Your Beak: 10 Amazing Birds With Teeth
The research sets out to identify the common ancestor to all modern birds and links them via the genes that lead to loss of dentin / toothlessness.
Along with what you've stated -- those species are ruled out as the common ancestor but most importantly, if what the genetic research concluded is true, it simultaneously rules out T. Rex, Velociraptor and other toothed theropod dinosaurs as potential candidates for the common ancestor to all modern birds.
Subject: RE: Genetic Evidence at last (Bird vs. Cretaceous Theropod Dinosaur)
Date: Mon, 16 Nov 2015 00:42:53 +0000
From: Feduccia, John AHi, here is a paper of possible interest. Best wishes, alan