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   PID: hpt/lnx 1.9.0-cur 2019-01-08   
   TID: hpt/lnx 1.9.0-cur 2019-01-08   
    Fossil of mosasaur with bizarre 'screwdriver teeth' found in Morocco   
      
      
     Date:   
         May 18, 2023   
     Source:   
         University of Bath   
     Summary:   
         Scientists have discovered a new species of mosasaur, a sea-dwelling   
         lizard from the age of the dinosaurs, with strange, ridged teeth   
         unlike those of any known reptile. Along with other recent finds   
         from Africa, it suggests that mosasaurs and other marine reptiles   
         were evolving rapidly up until 66 million years ago, when they were   
         wiped out by an asteroid along with the dinosaurs and around 90%   
         of all species on Earth.   
      
      
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   FULL STORY   
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   Scientists have discovered a new species of mosasaur, a sea-dwelling   
   lizard from the age of the dinosaurs, with strange, ridged teeth unlike   
   those of any known reptile. Along with other recent finds from Africa, it   
   suggests that mosasaurs and other marine reptiles were evolving rapidly   
   up until 66 million years ago, when they were wiped out by an asteroid   
   along with the dinosaurs and around 90% of all species on Earth.   
      
   The new species, Stelladens mysteriosus, comes from the Late Cretaceous   
   of Morocco and was around twice the size of a dolphin.   
      
   It had a unique tooth arrangement with blade-like ridges running down   
   the teeth, arranged in a star-shaped pattern, reminiscent of a cross-head   
   screwdriver.   
      
   Most mosasaurs had two bladelike, serrated ridges on the front and back   
   of the tooth to help cut prey, however Stelladens had anywhere from four   
   to six of these blades running down the tooth.   
      
   "It's a surprise," said Dr Nick Longrich from the Milner Centre for   
   Evolution at the University of Bath, who led the study. "It's not like   
   any mosasaur, or any reptile, even any vertebrate we've seen before."   
   Dr Nathalie Bardet, a marine reptile specialist from the Museum of   
   Natural History in Paris, said: "I've worked on the mosasaurs of Morocco   
   for more than 20 years, and I'd never seen anything like this before --   
   I was both perplexed and amazed!"  That several teeth were found with   
   the same shape suggests their strange shape was not the result of a   
   pathology or a mutation.   
      
   The unique teeth suggest a specialised feeding strategy, or a specialised   
   diet, but it remains unclear just what Stelladens ate.   
      
   Dr Longrich said: "We have no idea what this animal was eating, because   
   we don't know of anything similar either alive today, or from the   
   fossil record.   
      
   "It's possible it found a unique way to feed, or maybe it was filling   
   an ecological niche that simply doesn't exist today. The teeth look like   
   the tip of a Phillips-head screwdriver, or maybe a hex wrench.   
      
   "So what's it eating? Phillips head screws? IKEA furniture? Who knows."   
   The teeth were small, but stout and with wear on the tips, which seemed   
   to rule out soft-bodied prey. The teeth weren't strong enough to crush   
   heavily armoured animals like clams or sea urchins, however.   
      
   "That might seem to suggest it's eating something small, and lightly   
   armoured - - thin-shelled ammonites, crustaceans, or bony fish -- but   
   it's hard to know," said Longrich. "There were weird animals living   
   in the Cretaceous- ammonites, belemnites, baculites -- that no longer   
   exist. It's possible this mosasaur ate something, and occupied a niche,   
   that simply doesn't exist anymore, and that might explain why nothing   
   like this is ever seen again.   
      
   "Evolution isn't always predictable. Sometimes it goes off in a unique   
   direction, and something evolves that's never been seen before, and   
   then it never evolves again."  The mosasaurs lived alongside dinosaurs   
   but weren't dinosaurs. Instead, they were giant lizards, relatives of   
   Komodo dragons, snakes, and iguanas, adapted for a life at sea.   
      
   Mosasaurs evolved around 100 million years ago, and diversified up to   
   66 million years ago, when a giant asteroid hit the Yucatan Peninsula   
   in Mexico, plunging the world into darkness.   
      
   Although scientists have debated the role of environmental changes   
   towards the end of the Cretaceous in the extinction, Stelladens, along   
   with recent discoveries from of Morocco, suggests that mosasaurs were   
   evolving rapidly up to the very end -- they went out at their peak,   
   rather than fading away.   
      
   The new study shows that even after years of work in the Cretaceous of   
   Morocco, new species are continuing to be discovered. The reason may be   
   that most species are rare.   
      
   The authors of the study predict that in a very diverse ecosystem,   
   it may take decades to find all of the rare species.   
      
   "We're not even close to finding everything in these beds," said Longrich,   
   "This is the third new species to appear, just this year. The amount of   
   diversity at the end of the Cretaceous is just staggering."  Nour-Eddine   
   Jalil, a professor at the Natural History Museum and a researcher at   
   Univers Cadi Ayyad in Morocco, said: "The fauna has produced an incredible   
   number of surprises -- mosasaurs with teeth arranged like a saw, a   
   turtle with a snout in the form of snorkel, a multitude of vertebrates   
   of various shapes and sizes, and now a mosasaur with star-shaped teeth.   
      
   "We would say the works of an artist with an overflowing imagination.   
      
   "Morocco's sites offer an unparalleled picture of the amazing biodiversity   
   just before the great crisis of the end of the Cretaceous."   
       * RELATED_TOPICS   
             o Plants_&_Animals   
                   # New_Species # Nature # Frogs_and_Reptiles   
             o Earth_&_Climate   
                   # Ecology # Environmental_Awareness # Exotic_Species   
             o Fossils_&_Ruins   
                   # Dinosaurs # Evolution # Fossils   
       * RELATED_TERMS   
             o Ichthyosaur o Dinosaur o Feathered_dinosaurs o   
             Recent_single-origin_hypothesis o Homo_(genus) o Jurassic o   
             Homo_heidelbergensis o Timeline_of_evolution   
      
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   Story Source: Materials provided by University_of_Bath. Note: Content   
   may be edited for style and length.   
      
      
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   Related Multimedia:   
       * The_teeth_with_strange_ridges   
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   Journal Reference:   
      1. Nicholas R. Longrich, Nour-Eddine Jalil, Xabier Pereda-Suberbiola,   
         Nathalie Bardet. Stelladens mysteriosus: A Strange New   
         Mosasaurid (Squamata) from the Maastrichtian (Late Cretaceous)   
         of Morocco. Fossils, 2023; 1 (1): 2 DOI: 10.3390/fossils1010002   
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   Link to news story:   
   https://www.sciencedaily.com/releases/2023/05/230518120907.htm   
      
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