Here's an interesting Retraction in Nature. 2013 Sep 12;501(7466):262. .. it states something of peculiar interest:
The first theropod dinosaurs arose during the Triassic...
"...The hind limbs of Late Triassic epoch theropods lack osteological evidence for an avian reversed hallux and also display other functional differences from birds."
We must find a theropod from the Triassic to constitute an ancestor for Archeopteryx (a true bird)... otherwise, birds did not and could not have evolved from theropod dinosaurs.
Abstract
"...The study of fossilized footprints and tracks of dinosaurs and other vertebrates has provided insight into the origin, evolution and extinction of several major groups and their behaviour; it has also been an important complement to their body fossil record. The known history of birds starts in the Late Jurassic epoch (around 150 Myr ago) with the record of Archaeopteryx, whereas the coelurosaurian ancestors of the birds date back to the Early Jurassic. The hind limbs of Late Triassic epoch theropods lack osteological evidence for an avian reversed hallux and also display other functional differences from birds. Previous references to suggested Late Triassic to Early Jurassic bird-like footprints have been reinterpreted as produced by non-avian dinosaurs having a high angle between digits II and IV and in all cases their avian affinities have been challenged. Here we describe well-preserved and abundant footprints with clearly avian characters from a Late Triassic redbed sequence of Argentina, at least 55 Myr before the first known skeletal record of birds. These footprints document the activities, in an environment interpreted as small ponds associated with ephemeral rivers, of an unknown group of Late Triassic theropods having some avian characters."
(Source)
Take note of the last sentence. I have predicted "birds arose from aquatic environments" -- well ain't that something!
"...These footprints document the activities, in an environment interpreted as small ponds associated with ephemeral rivers, of an unknown group of Late Triassic theropods having some avian characters."
Ponds... aquatic... back to the "water's edge" from whence all life was begat.
"...Ephemeral rivers are rivers that do not always flow, that is, they dry up. How often, and for how long they dry up varies. It depends on the river."
See attached pic of such an "ephemeral river".
Swimming... enabled birds to fly.
I have DELIVERED TO YOU what the proto-ancestor of modern birds... as I predict will be... aquatic... semi-aquatic from such an environment as the one shown. LOL.
:-P from "...an unknown group of Late Triassic theropods having some avian characters."
Now, if Protoavis (also dated to the triassic, but by all accounts is a well-formed bird), then we'll just have to push that time-frame in the Triassic, back a bit more. But for now.. this evidence suffices.
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This is funny. In light of the Nature "Retraction". The Major Groups of Coelurosaurs "...Warning: You are entering an area of taxonomic research that is constantly changing. The phylogeny of this group of theropods is debated by paleontologists involved in its study, and new classifications are proposed several times a year! We will attempt to keep this site updated, but for now, as you warily maneuver through the shadowy byways of this theropod exhibit, remember that the relationships of this diverse group are not yet understood fully. It is both a frustrating and exciting area of research. So tread carefully from here on…and watch the shadows! Hungry beasts lurk ahead!" Never seen a web page open with that kind of disclaimer on it. WOW! Wow could that be? The dino-bird hypotheses people already know everything. |
From what I gather from Paleontology 101 as it currently stands, and the "Retraction" by Nature ...
GEOL 104: Theropoda II, Coelurosauria: Tyrant Kings and ...
Oct 14, 2014 -"Among the most primitive and oldest known coelurosaurs are the basal *tyrannosauroids Proceratosaurus of the Middle Jurassic of England and Kileskus of Russia. Only the skull of the former, and skull, hand, and foot bones of the latter, are known at present. However, the most primitive known coelurosaur is actual a relatively late one: Bicentenaria of the mid-Cretaceous of Argentina. It shares with basal tyrannosauroids and basal maniraptoriforms the same general body plan: relatively small (2-4 m) slender animals with skulls full of small ziphodont teeth. Their narrow grasping hands suggest they adapted to catching small prey; their light build, slender limbs, and narrow dynamic stabilizing tail suggests relatively agile animals (useful both in chasing prey and in avoiding predators)." (Source)
[* Tyrannosaurus rex, one of the last, and also the largest known tyrannosaur.]
But they're oh so positive, "birds evolved from" these beasts... 100 million years after birds were already alive & well and long since proliferating across the planet.
So, the "oldest known coelurosaurs" date to the Middle Jurassic... about the time Archeopteryx was already a fully developed bird.
And the "oldest known bird" date to the late Jurassic. (Archeopteryx). Right?
The Nature retraction stated:
"...The known history of birds starts in the Late Jurassic epoch (around 150 Myr ago) with the record of Archaeopteryx, whereas the coelurosaurian ancestors of the birds date back to the Early Jurassic. The hind limbs of Late Triassic epoch theropods lack osteological [note: bone/skeletal] evidence for an avian reversed hallux and also display other functional differences from birds."
So those are not going to be the ancestor to (perching) birds... and continues,
"....Previous references to suggested Late Triassic to Early Jurassic bird-like footprints have been reinterpreted as produced by non-avian dinosaurs having a high angle between digits II and IV and in all cases their avian affinities have been challenged."
So they too, could not be the ancestors of birds. And this is back in the LATE TRIASSIC... long before T-Rex and Velociraptor evolved.
[...BTW they do indeed have the fossil skeletons of T-Rex to rebuild upon and create more "3D Imaging" footprints if necessary, so they should know if they are actually "ancestors to birds". But since T- Rex lived 70 million years AFTER archeopteryx, such a demonstration would be pointless, anyway... but nobody is following the fossil record these days anyway... so to do so would be right up the dino-bird hypothesist' alley.]
Coelurosaurs are merely "Extremely bird-like theropod dinosaurs". But not birds and not the ancestors of birds, either.
With Common Ancestry... it is EXPECTED... PREDICTED... to have "bird like dinosaurs" and "dinosaur-like birds". That's Evolution (Charles Darwin style). But with the dino-bird crowd -- there are no "gray areas" as there are suppose to be. There are NO TRANSITIONAL FORMS between archosaur and bird... they are all "dinosaur" including birds. The whole idea of Evolution and diversification from "basal archosaurs into birds and dinosaurs and crocodiles" was flushed down the tubes with a fanatic hypothesis that birds arose from cretaceous dinosaurs.
Evidence weighs heavy for the non-relation between bird and dinosaur in the Jurassic.
So when pushing back the geological time-clock, into the Triassic... before the first documented (known) true bird -- after they retract the dubious misinformation about "...hind limbs of Late Triassic epoch theropods lack osteological [edit: bone/skeletal] evidence for an avian reversed hallux and also display other functional differences from birds."... and then proceed to explain a potential candidate that might be, a potential ancestor to birds :
"...Here we describe well-preserved and abundant footprints with clearly avian characters from a Late Triassic redbed sequence of Argentina, at least 55 Myr before the first known skeletal record of birds. These footprints document the activities, in an environment interpreted as small ponds associated with ephemeral rivers, of an unknown group of Late Triassic theropods having some avian characters."
(Source)
Again... an "unknown group" in the Triassic... in a semi-aquatic habitat.
It was merely a pipe dream... for now.
At least that is my understanding of the Nature Retraction.
Have it the way of Nature's retraction (placed in the Triassic)... or Dr. Alan Feduccia's way, placed in the Tertiary: (The Eocene is the second of five epochs in the Tertiary Period — the second of three epochs in the Paleogene — and lasted from about 55.8 to 33.9 million years ago...)
(1/8/2015) "...These tracks never were considered dinosaurian, but look identical to those of small shorebirds, now called stints. The hundreds of tracks even show behavior virtually identical to modern shorebirds. The deposits were not properly assigned and are Eocene. Finally, the reason they lack a hallux is that they, like modern shorebirds that also lack the hallux, are not perching birds. The hallux is "exclusively" an adaptation for perching in trees."
Oh well either way... I WIN because I already know how the Jurassic-Triassic world looked. Lots of beds of water abroad and the ancestors of birds were taking a dip and swimming. The earliest birds were swimmers -- etched in their anatomy like no other species.
The oldest amniotes date from Upper Carboniferous (310 My) when animals came out on land, and the rise of birds was somewhere around the Triassic 250-200 Mya.
And, the oldest known bird.. indeed: "Archaeopteryx lived near a large shallow, coastal lagoon. Archaeopteryx fossils have been found only in the Atlmuhl valley in Bavaria, Germany..."
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