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   PID: hpt/lnx 1.9.0-cur 2019-01-08   
   TID: hpt/lnx 1.9.0-cur 2019-01-08   
    Ancient herbivore's diet weakened teeth leading to eventual starvation,   
   study suggests    
      
     Date:   
         June 9, 2023   
     Source:   
         University of Bristol   
     Summary:   
         Researchers have shed light on the life of the ancient reptile   
         Rhynchosaur, which walked the earth between 250-225 million years   
         ago, before being replaced by the dinosaurs.   
      
      
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   FULL STORY   
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   A team of researchers from the University of Bristol have shed light   
   on the life of the ancient reptile Rhynchosaur, which walked the earth   
   between 250-225 million years ago, before being replaced by the dinosaurs.   
      
   Rhynchosaurs are a little-understood group of roughly sheep-sized ancient   
   reptiles that thrived during the Triassic Period, a time of generally   
   warm climates and tough vegetation.   
      
   In the new study, the researchers studied specimens found in Devon and   
   used CT scanning to see how the teeth wore down as they fed, and how   
   new teeth were added at the backs of the tooth rows as the animals grew   
   in size.   
      
   The findings, published today in Palaeontology, show that these early   
   herbivores likely eventually starved to death in old age, the vegetation   
   taking its toll on their teeth.   
      
   "I first studied the rhynchosaurs years ago," said team-leader Professor   
   Mike Benton from Bristol's School of Earth Sciences, "and I was amazed   
   to find that in many cases they dominated their ecosystems. If you found   
   one fossil, you found hundreds. They were the sheep or antelopes of their   
   day, and yet they had specialized dental systems that were apparently   
   adapted for dealing with masses of tough plant food."  Dr Rob Coram,   
   who discovered the Devon fossils, said: "The fossils are rare, but   
   occasionally individuals were entombed during river floods. This has   
   made it possible to put together a series of jaw bones of rhynchosaurs   
   that ranged in age from quite young, maybe even babies, through adults,   
   and including one particularly old animal, a Triassic old-timer whose   
   teeth had worn right down and probably struggled to get enough nutrition   
   each day."  "Comparing the sequence of fossils through their lifetime,   
   we could see that as the animals aged, the area of the jaws under wear   
   at any time moved backwards relative to the front of the skull, bringing   
   new teeth and new bone into wear," said Thitiwoot Sethapanichsakul who   
   studied the jaws as part of his MSc in Palaeobiology. "They were clearly   
   eating really tough food such as ferns, that wore the teeth down to the   
   bone of the jaw, meaning that they were basically chopping their meals   
   by a mix of teeth and bone."  "Eventually, though, after a certain age   
   -- we're not sure quite how many years -- their growth slowed down and   
   the area of wear was fixed and just got deeper and deeper," added Dr   
   Coram. "It's like elephants today -- they have a fixed number of teeth   
   that come into use from the back, and after the age of seventy or so   
   they're on their last tooth, and then that's that.   
      
   "We don't think the rhynchosaurs lived that long, but their plant food   
   was so testing that their jaws simply wore out and presumably they   
   eventually starved to death."  The rhynchosaurs were an important part   
   of the ecosystems on land during the Triassic, when life was recovering   
   from the world's greatest mass extinction, at the end of the preceding   
   Permian Period. These animals were part of this recovery and setting   
   the scene for new types of ecologies when first dinosaurs, and later   
   mammals became dominant, as the modern world was being slowly constructed.   
      
   By comparing examples of earlier rhynchosaurs, such as those from Devon,   
   with later-occurring examples from Scotland and Argentina, the team   
   were also able to show how their dentitions evolved through time, and   
   how their unique teeth enabled them to diversify twice, in the Middle   
   and then in the Late Triassic.   
      
   But in the end, climate change, and especially changes of available   
   plants, seem to have enabled the dinosaurs to take over as the   
   rhynchosaurs died out.   
      
       * RELATED_TOPICS   
             o Plants_&_Animals   
                   # Extinction # Endangered_Plants # Nature   
             o Earth_&_Climate   
                   # Ice_Ages # Ecology # Climate   
             o Fossils_&_Ruins   
                   # Dinosaurs # Fossils # Ancient_DNA   
       * RELATED_TERMS   
             o Ichthyosaur o Dinosaur o Timeline_of_evolution o   
             Jurassic o Mammoth o Structure_of_the_Earth o Homo_(genus)   
             o Feathered_dinosaurs   
      
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   Story Source: Materials provided by University_of_Bristol. Note: Content   
   may be edited for style and length.   
      
      
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   Journal Reference:   
      1. Thitiwoot Sethapanichsakul, Robert A. Coram, Michael   
      J. Benton. Unique   
         dentition of rhynchosaurs and their two‐phase success as   
         herbivores in the Triassic. Palaeontology, 2023; 66 (3) DOI:   
         10.1111/pala.12654   
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   Link to news story:   
   https://www.sciencedaily.com/releases/2023/06/230609125712.htm   
      
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