Ianthasaurus

Name: Ianthasaurus ‭(‬Iantha River lizard‭)‬.
Phonetic: E-an-fah-sore-us.
Named By: Robert R.‭ ‬Reisz‭ & ‬David Berman‭ ‬-‭ ‬1986.
Classification: Chordata,‭ ‬Synapsida,‭ ‬Pelycosauria,‭ ‬Edaphosauridae.
Species: I.‭ ‬hardestiorum‭ (‬type‭)‬.
Diet: Insectivore.
Size: Skull‭ ‬8‭ ‬centimetres long,‭ ‬body length around‭ ‬75‭ ‬centimetres.
Known locations: USA,‭ ‬Kansas‭ ‬-‭ ‬Stanton Formation,‭ ‬Rock Lake Member.
Time period: Kasimovian of the Carboniferous.
Fossil representation: Skull and partial remains.

       In the simplest terms,‭ ‬Ianthasaurus was a smaller and earlier relative to the famous Edaphosaurus,‭ ‬However with this said there were many differences.‭ ‬First and perhaps most obviously is that generally Ianthasaurus were not as advanced in their physical developments,‭ ‬not surprising given that Ianthasaurus appeared in the Carboniferous whereas Edaphosaurus appears in the Permian.
       Most different though,‭ ‬Ianthasaurus seems to have had a very different lifestyle as an insectivorous predator as opposed to a herbivore.‭ ‬The main clue to this comes from the teeth which in Ianthasaurus are very slender and conical.‭ ‬This is a similar tooth form to other insectivorous creatures,‭ ‬and rows of many fine but sharp teeth are perfect for piercing the exoskeletons of invertebrates due to the high point pressure when the teeth press against the hard shell.‭ ‬Ianthasaurus is also credited with having a fairly gracile build,‭ ‬inferring that for a pelycosaur,‭ ‬it was actually quite fast and agile.
       Discoveries of sail-backed pelycosaurs are slowly becoming more common,‭ ‬and every time one is found the same old question of what was the sail for is asked.‭ ‬The first possible answer is thermoregulation,‭ ‬where the sail is flushed with blood to trigger either body heating in the sun,‭ ‬or cooling in the wind.‭ ‬Second plausible answer is display,‭ ‬where different forms of sail and perhaps colours between species and genera allow an individual to recognise another of its kind.‭ ‬Either one of these,‭ ‬and indeed both of them can be right.

       Ianthasaurus may actually help us to understand the origin of the sails of some pelycosaurs.‭ ‬With a lightweight build and teeth that are very much like those of insectivores,‭ ‬the evidence lends more towards an invertebrate hunting lifestyle for Ianthasaurus.‭ ‬Invertebrates and pelycosaurs have both been interpreted as ectothermic,‭ ‬which means that they rely upon the ambient temperature of their surroundings to raise and lower their body temperature accordingly.‭ ‬This also means that early in the morning,‭ ‬when temperatures are only starting to rise,‭ ‬both invertebrates and pelycosaurs would have been sluggish‭ (‬slow‭) ‬in their movements while their bodies heated up.‭ ‬But a predator with a sail on its back,‭ ‬say Ianthasaurus,‭ ‬would have a larger surface area to expose to the sun,‭ ‬meaning that it could warm up and become more active much earlier than those without.‭ ‬It terms of Ianthasaurus,‭ ‬it would have been able to get going and hunt down invertebrates that were still too sluggish themselves to get away.‭ ‬By gorging themselves on invertebrates in the morning,‭ ‬Ianthasaurus would then be able to spend the warmer periods of the day resting and digesting the results of their breakfast hunting.

Further reading
-‭ ‬Ianthasaurus hardestii n.‭ ‬sp.,‭ ‬a primitive edaphosaur‭ (‬Reptilia,‭ ‬Pelycosauria‭) ‬from the Upper Pennsylvanian Rock Lake Shale near Garnett,‭ ‬Kansas‭ ‬-‭ ‬Canadian Journal of Earth Sciences‭ ‬23‭ (‬1‭)‬:‭ ‬77‭–‬91.‭ ‬-‭ ‬Robert R.‭ ‬Reisz‭ & ‬David Berman‭ ‬-‭ ‬1986.

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