Eat or Be Eaten

                                                    Eat or Be Eaten
 


  The evolution and biological adaptations that have occurred on the Earth have had their good days and their bad days.  Unfortunately, the final curtain isn’t drawn on whether individual adaptations are good or bad, until life gets down to living.  Likewise, the success of particular evolutionary adaptations by nature to pre-existing forms is only determined in the furnace of life, by the literal act of living.
  Evolutionary experiments like bones, muscles, joints and associated developments in jaw size and strength would certainly be included on the accounts receivable side of nature’s daily ledger.  Bones, muscles, and joints have been included in generations of successful life forms for millions of years.  Jaw strength, on the other hand, is like a grandchild of these three ancient developments.  All three are needed to make an effective jaw, yet jaw strength has been included in such a large variety of species and forms that its entry into the evolutionary hall of fame is assured.
  Millions of movie enthusiasts watched, eyes-riveted to the screen, the original Jaws movie and its subsequent sequels.  The adrenalin filled evolutionary response of humans to inherited fears of bloody jaws reaching for them in their nightmares, is the last thing eons of prey saw.
  But forget about the feather-weight great white shark.  A 400 million year old, 33 foot long, 5 ton, armour-plated, bone crushing fish called Dunkleosteus terrelli is the most recently discovered heavy weight contender for the title of biggest, baddest, bite.
  The largest of the armoured group of predatory fish the placoderms.  The Dunkleosteus ate whatever it wanted!  But palaeontologists think its diet included large molluscs (we do mean large), arthropods, distant relatives of the great white pretender and probably other placoderms were on the daily menu.  Considering Dunkleosteus’s estimated 8,000 pounds of pressure per square inch rivals or exceeds all known predators, it probably had little trouble slicing through the skin, flesh and bone of all residents of its age.
  In fact, palaeontologist think Dunkleosteus was one of the first vertebrates with enough jaw strength to totally fragment its prey before swallowing, exerting an estimated 1200 pounds of bite force along its jagged jaws, enough to slice through the defences of its prey.
  Which brings up an interesting question, just how do you test the jaw strength of a 400 million year old predatory fish?  Well, researchers started by reconstructing the Dunkleosteus’s jaw muscles from the grooves of a well preserved fossil.  Then, they made foam rubber casts of the muscle cavities in the Dunkleosteus’s skull replica.  This allowed them to use the length and cross section of each muscle to calculate the Dunkleosteus’s maximum contraction force based on the typical strength of a modern vertebrate.  These values when combined with two dimensional simulations of the Dunkleosteus’s jaw, which palaeontologists think could pivot at several points, which gave the creature the ability to hold the jaws open while crisscrossing muscles in the cheeks contract, allowed them to calculate the estimates of Dunkleosteus’s jaw strength.
  Palaeontologists think Dunkleosteus’s jaw and mouth structure indicate it may have sucked prey into its maw, before biting.  But, suction could have helped it deal with agile prey like sharks, they point out.
  Despite its powerful bite and supposed dominance of the ancient seas, Dunkleosteus disappeared from the fossil record after a 100 million year run.  But this would not be the final act in the evolutionary story of jaw strength.
  Today jaw strength is a proven tool in the arsenal of modern predators, including sharks, alligators, majestic lions, and the ornery hyena, to name but a few.  All of these predators can generate up to 3,000 pounds of bite force, more then enough to put them in the elite class of predators in the animal kingdom with unmatched jaw strength.
  What does the evolutionary future of jaw strength entail?  Will nature come up with new developments in jaw structure and strength, most assuredly she will, the only question of course is whether they will endure the test of survival.