Research to answer a 'crushing' evolutionary question

October 5, 2016 by Dean Maskevich, New Jersey Institute of Technology
The skull of a placodont - Placodus gigas - clearly showing upper and lower teeth well suited to crushing the shells of creatures that were a primary source of food. Credit: New Jersey Institute of Technology

Studying the physical features of long-extinct creatures continues to yield surprising new knowledge of how evolution fosters traits desirable for survival in diverse environments. Placodonts are a case in point—specifically, the placodont teeth that Stephanie Crofts, an NJIT post-doctoral researcher, has written about in an article recently published in the journal Paleobiology. Now working with Assistant Professor of Biological Sciences Brooke Flammang in her Central King Building lab, Crofts is the co-author of "Tooth occlusal morphology in the durophagous marine reptiles, Placodontia (Reptilia: Sauropterygia)."

Placodonts, a group of extinct marine reptiles, lived at the beginning of the Triassic Period, the beginning of the age of dinosaurs, some 250 million years ago. They thrived in the shallows of the sea that split the ancient supercontinent Pangea. Their fossils have been found in Germany, Switzerland and Italy, and new specimens are being discovered in China.

All placodonts have teeth on their upper and lower jaws, as well as a set of teeth lining the roof of the mouth. But over their evolutionary history, Crofts explains, placodonts developed specialized "crushing" teeth well-suited for eating the "hard prey" creatures that shared their environment—creatures with thick shells, like clams or mussels.

The evolutionary ancestors of placodonts had long, pointy teeth, even on the roof of the mouth, especially suitable for catching soft-bodied prey. In contrast, placodonts are easily identified by their crushing teeth, bulbous in early placodonts and flattened in species that occur later in the evolutionary lineage. The basic question for Crofts: How well did these teeth function, and did later placodonts achieve an "optimal" crushing tooth?

International Investigation

Working with and international team of colleagues she met before joining NJIT in 2016, Crofts, traveled to museums throughout Europe to collect data on the shape of placodont teeth. Crofts' collaborators were James Neenan, a research fellow at the Oxford Museum of Natural History in England, Torsten Scheyer, associate professor at the University of Zurich's Palaeontological Institute and Museum, and Adam Summers, professor in the University of Washington's Department of Biology and head of the comparative vertebrate biomechanics lab at the university's marine field station, Friday Harbor Laboratories. Their investigative effort was made possible by funding from the Society of Vertebrate Paleontology, the University of Washington, the National Science Foundation and Swiss National Science Foundation.

In the course of her travel, Crofts compared the shapes of placodont teeth in the museum collections to models that tested how efficiently the teeth would break shells and how well they resisted breaking under pressure. Based on these models, Crofts and her team were able to predict that placodonts should have evolved a slightly rounded tooth surface, which would break shells efficiently without damaging the tooth itself. While some later occurring placodonts did just that, evolution equipped the latest known occurrences of these creatures with teeth that had quite different and very intriguing characteristics.

Instead of the predicted optimal tooth, this group of placodonts developed a complex with a shallow, crescent-shaped furrow surrounding a small cusp on the principal crushing teeth. As Crofts and her collaborators suggest in the Paleobiology article, this tooth structure may have worked in a way similar to the function proposed for early hominin molars—with the furrow holding prey in place while the small cusp applies the force needed to break through the prey's shell. Further, Neenan and Scheyer have demonstrated that there is a slower rate of tooth replacement in this same group of placodonts, likely because changes in tooth shape protect the tooth from failure.

Palaeontological Perspectives

Crofts, who completed her Ph.D. at the University of Washington in 2016, brings a paleontological perspective and interest in the evolution of functional morphology to the increasing range of research under way in Flammang's Fluid Locomotion Laboratory. Flammang is the founding director of the lab, and with the assistance of Crofts and other colleagues is taking a multidisciplinary look at nature's marine propulsion systems. Crofts became interested in the postdoc position available at NJIT when she met Flammang while both were taking a course at Brown University on X-Ray Reconstruction of Moving Morphology (XROMM), an advanced technique for producing highly detailed 3D video of skeletal movement.

Crofts' current work at NJIT integrates comparative anatomy and physiology, biomechanics, hydrodynamics, and the use of biologically inspired robotic devices to investigate how aquatic organisms interact with their environment and drive the evolution of morphology and function. In addition to increasing the fund of basic scientific knowledge, it's work that has implications for the design of various types of submersible vehicles, including fully autonomous vehicles.

Reflecting on her research involving placodonts, Crofts says that it is a "window into the complexities and possibilities" inherent to the process of evolution. The placodonts she studied and wrote about surprised with teeth differing very significantly from those which evolved in other related species. At NJIT, Crofts is continuing the search for new insights into how evolution shapes the functional relationship of all creatures—including humans—with the surrounding world.

Explore further: The placodonts are fellow Europeans

More information: Stephanie B. Crofts et al, Tooth occlusal morphology in the durophagous marine reptiles, Placodontia (Reptilia: Sauropterygia), Paleobiology (2016). DOI: 10.1017/pab.2016.27

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Ojorf
4.2 / 5 (5) Oct 06, 2016
The problem is that some world views conform to reality (as far as we know) and some do not. They are not equal.
jonesdave
3.9 / 5 (7) Oct 06, 2016
...is absolutely non-scientific. It does nothing to prove anything about evolution. What it should say is,

Studying these physical features yields new knowledge on what traits in creatures had for survival in diverse environments.

You can the word "had" to "developed by evolution" or "amazingly created" depending on your worldview.



Wrong. SOME of the creatures may have had certain traits that were selected for due to a change in environment. Evolution therefore "fostered" that trait so that it became prevalent within the population. Others traits will have arisen in the population due to a mutation that was favourable. Those that had it did well, and produced more offspring, until that trait became dominant.
You aren't suggesting that Darwin's finches were already pre-adapted to the islands they found themselves upon?
cgsperling
2.3 / 5 (3) Oct 06, 2016
BartV: Do you really want to worship a deity that would spend a few million years messing around with placodont teeth?
jonesdave
4 / 5 (4) Oct 06, 2016
Evolution therefore "fostered" that trait...


Dead wrong. There is zero scientific proof of this.



Yes, there is. Read up on the peppered moth, for instance. Or maybe, next time you're in Africa without the required shots, ask yourself why you managed to contract malaria.
And then show us the scientific proof for whatever woo you believe in.
Captain Stumpy
4 / 5 (4) Oct 07, 2016
"Evolution" as I use, just to be straight, is not a re-arranging of genes, or selection from a gene pool, etc. But it is the process of new genes appearing out of nowhere to make new organisms
@barfV
if only there were some way to clearly, concisely communicate the definitions of certain terms so that we could establish that word [x] means exactly [insert definition]...

but wait, it's a technical term, so what we need is a specific lexicon that defines it as it is technically used... if only we could do something like that...
WAIT... what's this?
http://www.dictio...volution

http://www.dictio...volutionhttps://www.britannica.com/science/evolution-scientific-theory

not one mention of "new genes appearing out of nowhere to make new organisms"????

and what's that?
there is evidence to support the definition and claims?
and arbitrarily redefining a word for your own delusional belief is called making sh*t up and lying?

who knew?
FredJose
2.3 / 5 (3) Oct 10, 2016
Others traits will have arisen in the population due to a mutation that was favourable.

You are grasping this out of thin air with zero supporting evidence. can you name those "favourable" mutations that occurred in these animals? You can't because you never observed them. In fact the number of "favourable" mutations are so few and far between that the evolutionary timeline is horribly too short for the amount of supposed "evolution" that is supposed to have occurred in the last 3 billion years..
Darwinian, single ancestor Evolution is a myth of the first kind. Live on in your dream worldview that doesn't meet reality.
FredJose
2.3 / 5 (3) Oct 10, 2016
support the definition

Yeah, the materialistic, humanistic definition of "science" excludes the idea of life arising from a hyper-intelligent, external designer, in spite of the clearly observable design in living organisms.

People who adhere to this worldview will forever be seeking and never finding solutions to their self-created problems:
1. How to get stars to form out of gas clouds all by themselves.
2. How to get planets to form out of dust clouds all by themselves.
3. How to get life to arise from ground/scum pond/heat vent etc. all by itself with no intelligent input and only random chemical and physical processes.
4. How to get a single ancestor to "evolve" via random mutations and natural selection into the life forms we see around today.
Dream on. But remember your life is far too short and also of far greater eternal importance to waste on such a dead end route.
jonesdave
3 / 5 (2) Oct 10, 2016
^^^^^Whoops, more creationist bollocks, I see. Why do these people even bother with science sites? Surely there are enough crank religious sites around to talk about this kind of drivel on.
TheGhostofOtto1923
3 / 5 (2) Oct 10, 2016
Yeah, the materialistic, humanistic definition of "science" excludes the idea of life arising from a hyper-intelligent, external designer
-while the fantastical, superstitionist definition of science demands it to the exclusion of all evidence-based theories.

And if superstitionists had their way they would forbid the exploration of such heresy. Because
Darwinian, single ancestor Evolution is a myth of the first kind. Live on in your dream worldview that doesn't meet reality
-As we can see they already have all the answers they will ever need.
jonesdave
3 / 5 (2) Oct 10, 2016
"science" excludes the idea of life arising from a hyper-intelligent, external designer, in spite of the clearly observable design in living organisms.


So, according to you, "it was god what did it." Yes, very scientific. Tell me, where did this super intelligent designer come from? Did it evolve, or was it just magicked into existence by some sort of supernatural jiggery pokery?
And why was it such a lazy bastard when it came to humans? I mean, using more than 98% of chimpanzee DNA as a template isn't showing much in the way of imagination, is it?

antialias_physorg
5 / 5 (1) Oct 10, 2016
1. How to get stars to form out of gas clouds all by themselves.

Gravity.
2. How to get planets to form out of dust clouds all by themselves.

Gravity.
3. How to get life to arise from ground/scum pond/heat vent etc. all by itself with no intelligent input and only random chemical and physical processes.

Still very much being researched. Though we do know that the building blocks of life (amino acids) do form under varying conditions by themselves without any intelligent input. In any case this is not part of the theory of evolution. This is part of the theory of abiogenesis.

4. How to get a single ancestor to "evolve" via random mutations and natural selection into the life forms we see around today.

That's what we have the fossil record for which shows this pretty clearly. That random mutation and natural selection works to adapt a species (or produce speciation) can be demonstrated in the wild as well as in the lab.

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