Sunday, September 25, 2016

Machairoceratops: Beast of the Week

This week we will be looking at another recently discovered horned dinosaur.  Enter Machairoceratops cronusi!

Machairoceratops was a ceratopsian dinosaur, which means it was in the same group as the more famous, Triceratops.  Within this group, however, it was more closely related to Diabloceratops and NasutoceratopsMachairocearatops' name translates to "Bent Knife Horned Face".  This is in reference to the shape of the two horns that grew from the top of the dinosaur's frill.  The species name, "cronusi" is after the mythical Greek god, Cronus, who cut off his dad's testicles with a curved sword.  (Next time you think your family has drama, remember that.)  In life, Machairoceratops would have been a plant-eater.  It lived in what is now Utah, USA, during the Cretaceous period, about 77 million years ago.  From beak to tail it would have measured about twenty feet long based on the skull. (Only the skull was found.)

Two rival Machairoceratops use their horns to lock into one another as they engage in a shoving match.

Like its relatives, Machairoceratops had a beak, a frill behind its head, and horns...very unique horns.  I know I say "unique" a lot in reference to ceratopsians, but it holds true!  Especially when it comes to this genus.  The two horns on the top of the frill curve forward and downward.  Frill horns aren't unheard of ceratopsians...but this exact orientation and curvature combined with their length, is.  It also had one horn over each eye which curved slightly upwards.  Due to the fragmentary remains of the skull, we sadly don't know what kind of horn ornamentation Machairoceratops had over its snout, if any at all.

Known fossil material from Machairoceratop's skull.  Image is from the paper by Eric K. Lund, Patrick M. O’Connor, Mark A. Loewen, Zubair A. Jinnah, referenced below.

As is the case with all ceratopsians, we don't know exactly why Machairoceratops' horns and frill evolved the way they did.  But it is very likely it had something to do with interacting with other members of its species.  If ceratopsian horns and frills were purely for defense against predators, they would likely be more uniform from species to species.  But this isn't the case.  Typically, when a variety of different, but related animals have the same sort of trait that is unique in form to each species, it has to do with some sort of intraspecies communication, like sexual display.  Just look at modern songbirds and their variety of colors and calls, or ungulates and their horns/antlers as modern comparisons. When it came to Machairoceratops, I felt that the overall shape that the brow and frill horns made together looked like it might serve well for combating rivals in head-to-head pushing behavior.  The antlers of modern reindeer also form this forward-facing crescent form, and they use them similarly.  Can I prove this was exactly how Machairoceratops used its horns?  Of course not.  But it's possible and also fun to think about.

That is all for this week!  As always please feel free to comment below or on our facebook page!


Eric K. Lund, Patrick M. O’Connor, Mark A. Loewen and Zubair A. Jinnah (2016). "A New Centrosaurine Ceratopsid, Machairoceratops cronusi gen et sp. nov., from the Upper Sand Member of the Wahweap Formation (Middle Campanian), Southern Utah". PLoS ONE. 11 (5): e0154403.


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