From Paleocast in September 2017.
This YouTube video parallels the large reptile tree (LRT, 1816+ taxa) by describing a wide gamut of vertebrate taxa. Dr. Joseph Keating of the University of Manchester School of Earth of Environmental Science is the professor of this 38-minute PowerPoint presentation.
Some critical thoughts:
The presentation starts off with the statement: “You are a fish.” That’s exciting and odd, but there is no monophyletic clade called ‘fish’. Keating’s presentation shows a ladyfish (genus Elops), which is not in the lineage of humans. More accurately:
- You are a chordate
- You are a craniate
- You are a vertebrate
- You are a gnathostome, etc.
Comparing shark jaw and pharyngeal ‘bones’ to human counterparts
Keating omitted the upper jaw counterpart in the human of the upper gill element in the shark. Missing elements in the human include the lacrimal, maxilla and premaxilla.
Keating continues with the out-dated tradition
that placental mammals diverged from one another 80 to 90 million years ago. This is falsified by the presence of Maiopatagium, Rugosodon and other members of Glires (= rodents, rabbits and kin) in the Early Jurassic, some 200 million years ago.
Keating has elephants splitting from edentates (Fig. 1), and dolphins splitting from cattle, neither of which is confirmed by the LRT. But that’s what you get with gene studies. Gosh, I’d hate to spend tens of thousands of dollars on tuition and several years at these universities to be forced to regurgitate these myths.
Keating gets the Archosauromorph/Lepidosauromorph split correct
at about 330 million years ago, but incorrectly puts birds in the Lepidosauromoph clade.
Keating incorrectly marks the genesis of tetrapods
at about 360 million years ago. We have tetrapod trackmakers in the Middle Devonian, at 390 million years ago.
To his credit,
Keating colors fish bones with tetrapod homologs (Fig. 2). Everyone knows now how easy that makes comparisons.
Keating correctly reports
that we (and bony fishes) share a last common ancestor with sharks about 450 million years ago, deep in the Ordovician. Keating does not indicate which shark was ancestral to bony fish. (It was Hybodus).
Keating’s image of human teeth
(Fig. 3) look unlike any human teeth I have ever seen.
Keating’s favorite group
is the jawless fishes, splitting from sharks at 500 million years. Sturgeons and paddlefish are not mentioned. Neither are Birkenia, thelodonts, osteostracans and heterostracans.
There are lots of pictures
of lampreys and hagfish, if that’s your thing, including how they fit into human cuisine.
When lancelets are introduced,
the concept of ‘Vertebrates’ is introduced. Keating reports that gills, brain, eyes, liver, heart, gall bladder, not vertebrae, are characters of vertebrates. Perhaps he is mixing up ‘craniates’ with ‘vertebrates. I think hagfish are inappropriate vertebrates, contra tradition. Call me old-fashioned, but vertebrae should be present in vertebrates.
According to Keating,
heterostracans document the earliest evidence of mineralized bone, the exoskeleton. Keating studied this material in detail with a µCT scanner. As everyone knows, heterostracans have a robust exoskeleton. Birkenia documents a much more primitive state of bone development.
have paired fins, the first taxa do this, according to Keating. Thelodus is the most primitive fish with paired fins in the LRT. The osteostracan, Hemicyclaspis, evolves later as a derived thelodont.
Placoderms are discussed with an emphasis on Dunkleosteus.
Due to taxon exclusion Keating has no idea how placoderms originated within the bony fish. Keating mistakenly reports placoderms were the first to develop jaws. Actually paddlefish did this, just following sturgeons.
The talk concludes
with Tiktaalik. Having a neck is a key trait according to Keating. Another unrelated fish with a neck capable of bending the skull left and right is the Lepidogalaxias, the salamander fish, nesting at the base of the bony ray-fin fish.
Here’s a bonus video
for those who have followed the ongoing clash between certain PhDs and this blogsite as it represents the website RepitleEvolution.com on a daily basis. The speaker, Julia Galef, describes the various mindsets involved and the psychological reason for their separate points-of-view.