‘Steak-knife’ teeth reveal ecology of oldest land predators

The first top predators to walk on land were not afraid to bite off more than they could chew, a University of Toronto Mississauga study has found.

Graduate student and lead author Kirstin Brink along with Professor Robert Reisz from U of T Mississauga’s Department of Biology suggest that Dimetrodon, a carnivore that walked on land between 298 million and 272 million years ago, was the first terrestrial vertebrate to develop serrated ziphodont teeth.

According to the study published in Nature Communications, ziphodont teeth, with their serrated edges, produced a more-efficient bite and would have allowed Dimetrodon to eat prey much larger than itself.

While most meat-eating dinosaurs possessed ziphodont teeth, fossil evidence suggests serrated teeth first evolved in Dimetrodon some 40 million years earlier than theropod dinosaurs.

“Technologies such as scanning electron microscope (SEM) and histology allowed us to examine these teeth in detail to reveal previously unknown patterns in the evolutionary history ofDimetrodon,” Brink said.

The four-meter-long Dimetrodon was the top of the terrestrial food chain in the Early Permian Period and is considered to be the forerunner of mammals.

According to Brink and Reisz’s research,Dimetrodon had a diversity of previously unknown tooth structures and were also the first terrestrial vertebrate to develop cusps – teeth with raised points on the crown, which are dominant in mammals.

The study also suggests ziphodont teeth were confined to later species of Dimetrodon, indicating a gradual change in feeding habits.

“This research is an important step in reconstructing the structure of ancient complex communities,” Reisz said.

“Teeth tell us a lot more about the ecology of animals than just looking at the skeleton.”

“We already know from fossil evidence which animals existed at that time but now with this type of research we are starting to piece together how the members of these communities interacted.”

Brink and Reisz studied the changes in Dimetrodonteeth across 25 million years of evolution.

The analysis indicated the changes in tooth structure occurred in the absence of any significant evolution in skull morphology. This, Brink and Reisz suggest, indicates a change in feeding style and trophic interactions.

“The steak knife configuration of these teeth and the architecture of the skull suggest Dimetrodonwas able to grab and rip and dismember large prey,” Reisz said.

“Teeth fossils have attracted a lot of attention in dinosaurs but much less is known about the animals that lived during this first chapter in terrestrial evolution.”

Contributing Source : University of Toronto



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  • bgrnathan

    NATURAL LIMITS TO EVOLUTION: Only micro-evolution, or evolution within biological “kinds,” is genetically possible (such as the varieties of dogs, cats, horses, cows, etc.), but not macro-evolution, or evolution across biological “kinds,” (such as from sea sponge to human). All real evolution in nature is simply the expression, over time, of already existing genes or variations of already existing genes. For example, we have breeds of dogs today that we didn’t have a few hundred years ago. The genes for these breeds had always existed in the dog population but never had opportunity before to be expressed. Only limited evolution or adaptation, variations of already existing genes and traits, is possible.
    The genes (chemical instructions or code) must first exist or otherwise the evolution cannot occur. Genes instruct the body to build our tissues and organs.  Nature is mindless and has no ability to design and program entirely new genes for entirely new traits. Nature can only work with the genetic ability already existing in species. Nature cannot perform the genetic engineering necessary to increase that genetic ability.
    Many people have wrong ideas of how evolution is supposed to work. Physical traits and characteristics are determined and passed on by genes – not by what happens to our body parts. For example, if a woman were to lose her finger this wouldn’t affect how many fingers her baby will have. Changing the color and texture of your hair will not affect the color and texture of your children’s hair. So, even if through physical exercise an ape’s muscles and bones changed so that it could walk upright it still would not be able to pass on this trait to its offspring. Only changes or mutations for traits that occur in the genetic code of reproductive cells (i.e. sperm and egg) can be passed on to offspring. Read the author’s popular Internet article, HOW DID MY DNA MAKE ME? Apes, by the way, are quite comfortable in how they walk, just as humans are quite comfortable in how they walk. Even a slight change in the position of a muscle or bone, for either, would be excruciatingly painful and would not be an advantage for survival.
    The new science of epigenetics shows that certain acquired traits from the environment that affect how genes are expressed may be passed on (i.e. whether a gene is turned on or off), but these certain acquired traits do not change or alter the fundamental structure or function of the genes themselves.
    Modern evolutionists believe and hope that over, supposedly, millions of years random genetic mutations in the genes of reproductive cells caused by environmental radiation will generate entirely new genes. This is total blind and irrational faith on the part of evolutionists. It’s much like believing that randomly changing the sequence of letters in a romance novel, over millions of years, will turn it into a book on astronomy! That’s the kind of blind faith macro-evolutionists have.
    When evolutionary scientists teach that random genetic mutations in species over, supposedly, millions of years caused by random environmental agents such as radiation, produced entirely new genes (i.e. genetic code or genetic information) leading to entirely new forms of life, they are not teaching science but simply a faith, a belief!
    What about natural selection? Natural selection doesn’t produce biological traits or variations. It can only “select” from biological variations that are possible and which have survival value. The term “natural selection” is a figure of speech. Nature doesn’t do any conscious selecting. If a variation occurs in a species (i.e. change in skin color) that helps the species survive then that survival is called being “selected.” That’s all it is. Natural selection is a passive process in nature, not a creative process.
    How could species have survived if their vital tissues, organs, reproductive systems, etc. were still evolving? A partially evolved trait or organ that is not complete and fully functioning from the start would be a liability to a species, not a survival asset. Plants and animals in the process of macro-evolution would be unfit for survival. For example, “if a leg of a reptile were to evolve (over supposedly millions of years) into a wing of a bird, it would become a bad leg long before it became a good wing” (Dr. Walt Brown, scientist and creationist). Survival of the fittest actually would have prevented evolution across biological kinds! Read my Internet article: WAR AMONG EVOLUTIONISTS! (2nd Edition).
    All species of plants and animals in the fossil record are found complete, fully-formed, and fully functional. This is powerful evidence that species did not come into existence gradually by any macro-evolutionary process but, rather, came into existence as complete and ready-to-go from the very beginning, which is possible only by special creation.
    All the fossils that have been used to support human evolution have been found to be either hoaxes, non-human, or human, but not non-human and human (i.e. Neanderthal Man was discovered later to be fully human). Textbooks and museums still continue to display examples and illustrations supporting human evolution which most evolutionists have rejected and no longer support. Many diagrams of ape-man creatures over the years were reconstructed according to evolutionary interpretations from disputable bones that have now been discredited but still being taught in school textbooks.
    What about genetic and biological similarities between species? Genetic information, like other forms of information, cannot happen by chance, so it is more logical to believe that genetic and biological similarities between all forms of life are due to a common Designer who designed similar functions for similar purposes. It doesn’t mean all forms of life are biologically related! Only within a true species can similarities be used as evidence for relationship because only within a true species can individuals be capable of mating and producing offspring.
    Also, so-called “Junk DNA” isn’t junk. Although these “non-coding” segments of DNA don’t code for proteins, they have recently been found to be vital in regulating gene expression (i.e. when, where, and how genes are expressed, so they’re not “junk”). Read my popular Internet article: HOW FORENSIC SCIENCE REFUTES ATHEISM
    The real issue is what biological variations are possible, not natural selection.
    Visit my latest Internet site: THE SCIENCE SUPPORTING CREATION .
    I discuss: Punctuated Equilibria, “Junk DNA,” genetics, mutations, natural selection, fossils, dinosaur “feathers,” the genetic and biological similarities between various species, etc., etc.
    Babu G. Ranganathan*
    (B.A. theology/biology)
    *I have had the privilege of being recognized in the 24th edition of Marquis “Who’s Who In The East” for my writings on religion and science. I have given successful lectures (with question and answer period afterward) before evolutionist science faculty and students at various colleges/universities.