RECONSTRUCTING THE QUEEN OF THE GORGONS: INOSTRANCEVIA spp.
The Late Permian has always fascinated me. The Permian witnessed profound geological and biological transformations, including the emergence of diverse terrestrial ecosystems and the dominance of unique species. The rich tapestry of life during the Late Permian, particularly early synapsids, fuels this fascination. Towards the end of the Permian, one group of specialised synapsids rose to dominance: the gorgonopsians. Traditionally referred to as “gorgonopsids”, this group of sabre-toothed killers had a nearly cosmopolitan range across the globe during the Late Permian.
The largest of the group is often disputed - though the gorgonopsian, Inostrancevia, currently holds this crown. Inostrancevia lived until the end of the Permian, successfully dominating ecosystems in modern-day Russia and Africa.
I’ve attempted reconstructions of this genus of gorgon before, although previous attempts involved eyeballing mounted skeletons quite a bit. Recently, however, I managed to get a hold of the elusive Pravoslavlev 1927 description of the genus; for context, Inostrancevia was first discovered by Russian Palaeontologist Vladimir Amalitsky in the 1890s during a series of digs in the Salarevo formation that uncovered multiple skeletal elements of the species - including two nearly complete skeletons now catalogued as PIN 2005/1578 (the lectotype specimen) and PIN 1758. Unfortunately, Amalitsky died in 1917 and failed to properly describe his findings. So, a colleague of his, Pavel Pravoslavlev, wrote up descriptions of some of the specimens Amalitsky found, including the two aforementioned skeletons of Inostrancevia, referred to as Inostrancevia alexandri (note: Pravoslavlev referred to PIN 2005/1578 as “Inostrancevia typus”, and PIN 1758 as “Inostrancevia secundus” throughout the text to distinguish the two specimens. Though he refers both to I. alexandri).
Pravoslavlev included a number of figures and measurements of a few Inostrancevia specimens, which makes my life a hell of a lot easier when reconstructing this extinct predator. Interestingly, Pravoslavlev comments that some of the material originally referred to the well-preserved duo is likely chimeric - with some elements, such as the left humerus and foreleg of PIN 1758 probably belonging to other individuals (I am not sure if this has been corrected in subsequent mounts of this specimen). This would make a lot of sense - there are quite a few specimens uncovered in these beds, and it’s possible that some individuals got mixed up during discovery or in preparation. Perhaps we’ll never know to what extent.
Dimensions
I’ve included a few of the measured dimensions of a few key Inostrancevia specimens described in Pravoslavlev 1927, including a large specimen of Inostrancevia latifrons - this specimen, PIN 2005/1856, was referred to the taxon “Amalitzkia vladimiri” by Pravoslavlev. More recently, Palaeontologist Leonid Tatarinov referred the specimen to Inostrancevia latifrons. While it remains unclear if the postcranial elements attributed to this specimen originate from the same individual, the scale of this material observed closely mirrors the proportions extrapolated from other Inostrancevia specimens, implying that at the very least, the bones of this specimen were likely creatures of comparable size. Take a good look at these measurements and think about what stands out here. (Note: I tried my best to translate the passage here, as the original text is in Russian. The exact location of each measurement may be a little more specific than what’s noted below).
Table 1: Assorted measurements of the Lectotype (PIN 2005/1578) and referred specimens (PIN 1758) of I. alexandri and the specimen PIN 2005/1856 (previously referred to “Amalitzkia vladimiri”, now referred to I. latifrons - note, the type specimen of Inostrancevia latifrons, PIN 2005/1857, is not the same as this specimen). Note the difference in skull size between the first two specimens.
All measurements are in mm.
You may have noticed that, despite the general resemblance in postcranial proportions, an observable difference is clear when examining the skull proportions of the referred I. alexandri specimen (PIN 1758) in comparison to the lectotype specimen. The former exhibits a proportionately larger skull - something pretty clear when eyeballing the skeletal mounts.
Photographs reveal a visibly crushed PIN 1758 skull, in stark contrast to the well-preserved condition of the lectotype. This degree of distortion however does not fully account for the significantly increased skull length, especially considering all other dimensions are also larger (excluding the width between the orbits), and the overall skull proportions and anatomy remain quite similar to those of the lectotype specimen. Pravoslavlev mentions this resemblance in his description, commenting how the anatomy of both crania is nearly similar despite the distortion, a fact further supported when scrutinizing figures of the skulls from multiple perspectives.
So this doesn’t seem like a case of distortion, which would not lead to the skull being larger as a whole (or the lectotype’s skull being smaller). Is one of the specimens perhaps chimeric? We know that PIN 1758 had some chimeric elements - however, the skull of PIN 1758 is actually preserved and articulated with the cervical column. Moreover, comparison with the proportions of other Inostrancevia (such as the newly discovered and described Inostrancevia africana, which we DEFINITELY know isn’t chimeric) actually favours the big-headed variant; the skull of I. africana is large compared to its body and follows almost the exact proportions of PIN 1758.
So is the lectotype chimeric? We have no idea, but it seems doubtful. Although it isn’t mentioned, part of the skull also seems articulated to the vertebral column, and the rest of the body doesn’t seem to have any jumbled parts due to the similar dimensions for the left and right limbs.
What is the deal then? Unfortunately, we’re probably not going to have a detailed up to date description of the Russian specimens of Inostrancevia any time soon, so whether these specimens are chimeric, different species, or perhaps a form of sexual dimorphism like that seen in some mammals, is yet to be uncovered.
Skeletal diagrams
If you’ve just scrolled down to here to look at the skeletals (probs what most of you have done anyways) then TL;DR just appreciate these are a long time in the making.
Inostrancevia alexandri
Skeletal reconstruction of Inostrancevia alexandri, based on the lectotype specimen (PIN 2005/1578) and referred specimen PIN 1758.
Scale bar = 1 metre.
Length along centra for this skeletal: ~2.95 metres long
Inostrancevia latifrons (=”Amalitzkia vladimiri”)
Skeletal reconstruction of Inostrancevia latifrons. Skull reconstruction represents “idealistic” reconstruction based on multiple skulls referred to Inostrancevia latifrons (namely, the type specimen, PIN 2005/1856 previously referred to “A. vladimiri”, and another specimen in the PIN which I cannot find the catalogue number for.) Sized based on PIN 2005/1856.
Scale bar = 1 metre.
Length along centra for this skeletal: ~3.7 metres long
