Megapnosaurus

Name: Megapnosaurus ‭(‬Big dead lizard‭)‬.
Phonetic: Me-gap-noe-sore-us.
Named By: Michael Ivie,‭ ‬Adam Slipinski‭ & ‬Piotr Węgrzynowicz‭ ‬-‭ ‬2001.
Synonyms: Syntarsus rhodesiensis,‭ ‬Syntarsus kayentakatae.
Classification: Chordata,‭ ‬Reptilia,‭ ‬Dinosauria,‭ ‬Saurischia,‭ ‬Theropoda,‭ ‬Coelophysidae.
Species: M.‭ ‬rhodesiensis‭ (‬type‭)‬,‭ ‬M.‭ ‬kayentakatae.
Diet: Carnivore.
Size: Around‭ ‬3‭ ‬meters long.
Known locations: USA‭ ‬-‭ ‬Arizona‭ ‬-‭ ‬Kayenta Formation and Zimbabwe.
Time period: Hettangian through to Pliensbachian of the Jurassic.
Fossil representation: Remains of well over thirty individuals.

       During the earliest portion of its taxonomic history Megapnosaurus was known as Syntarsus after the initial description by Raath in‭ ‬1969.‭ ‬Later a trio of other palaeontologists‭ (‬Ivie,‭ ‬Slipinski and Węgrzynowicz‭) ‬discovered that the name Syntarsus had already been given to a beetle in‭ ‬1869.‭ ‬In‭ ‬2001‭ ‬they renamed the dinosaur Syntarsus remains as Megapnosaurus,‭ ‬though this was controversial for two reasons.‭ ‬Usually the original describer of a genus is‭ ‬given the chance to correct the mistake,‭ ‬but Ivie,‭ ‬Slipinski and Węgrzynowicz took this task upon themselves because they believed that Raath was deceased.‭ ‬In fact not only was Raath very much alive,‭ ‬he and other palaeontologists were of the opinion that Syntarsus‭ (‬now Megapnosaurus‭) ‬should actually be treated as a synonym to the earlier Coelophysis due to the remarkable resemblance between these dinosaurs.
       Although the future of Megapnosaurus is uncertain,‭ ‬the remains of this dinosaur do reveal a number of features that allow us to get a greater insight into dinosaur behaviour and ecosystems of the early Jurassic.‭ ‬Dinosaur bones have growth rings that allow palaeontologists to reasonably establish the age of a dinosaur at the time of death,‭ ‬and in Megapnosaurus‭ ‬these rings indicate that‭ ‬this dinosaur could live for up to seven years.‭ ‬The scleral rings of the eyes are similar to those of nocturnal birds,‭ ‬thus indicating a possible nocturnal lifestyle where Megapnosaurus hunted under the cover of darkness.‭ ‬At up to three meters long,‭ ‬Megapnosaurus may have been capable of tackling herbivorous dinosaurs such as Anchisaurus and Scutellosaurus.
       In addition to all this,‭ ‬Megapnosaurus remains are known from North America‭ (‬USA‭) ‬and Africa‭ (‬Zimbabwe‭)‬,‭ ‬not only helping to establish that the continents were still mostly joined together in the early Jurassic,‭ ‬but that the point of origin for dinosaurs may have been what is now South America,‭ ‬where they then radiated out across the globe while the continents were still joined.‭ ‬Also,‭ ‬the remains of over thirty Megapnosaurus individuals have been found together in a bone bed in Zimbabwe.‭ ‬This could indicate gregarious social behaviour as seen in some birds today,‭ ‬or perhaps environmental conditions could have brought them together,‭ ‬such as clustering around a watering hole during a drought.

Further reading
-A non-destructive investigation of the skull of the small theropod dinosaur, Coelophysis rhodesiensis, using CT scans and rapid prototyping. A. Bristowe, A. Parrot, J. Hack, M. Pencharz & M. Raath - 2004.
-A juvenile coelophysoid skull from the Early Jurassic of Zimbabwe, and the synonymy of Coelophysis and Syntarsus. A Bristowe & M. A. Raath - 2004.
-Nocturnality in Dinosaurs Inferred from Scleral Ring and Orbit Morphology. L. Schmitz & R. Motani - 2011.

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