WIP - Archelon ischyros
Towards the end of 2019, I was very pleased to be commissioned by the brilliant Klaus Stiefel to produce a life-restoration of Archelon ischyros (OK, when I say "commissioned", what I really mean to say is: Klaus put out a call-to-arms on Facebook and I ran to the front of the queue! Still, he could always have turned me down, so...)
The article that this illustration accompanies is yet to be published, but here is a tantalysing sneak-preview of the work! I can't say any more now, but more details to come in 2020, I'm sure. In the meantime though, I just wanted to write a little about the thought processes behind the restoration work.
My initial instinct was to depict A. ischyros "in the blue" (in open water), but this poses specific technical challenges for a palaeoartist. The biggest consideration really is scale: it is difficult enough to convey scale underwater without visual references, but when dealing with extinct relatives of extant species the problem is compounded by the audience's assumptions about how big/small the subject "should" be.
This is all a matter of association: Put simply; in the mass-media world, we're used to seeing photogenic green sea turtles and anyone who has ever seen a nature documentary or visited an aquarium (or watched 'Finding Nemo'!) will have a notion of roughly how big they are and therefore how big they assume most turtles to be. Unless you already live in a turtle-rich environment, in which case you might assume olive ridley turtles to be representative of most turtles - it's all about what we're most used to seeing.
This is a key concept in semiotics and is tied in with Plato's theory of Ideas: that we all share a concept of the Ideal turtle - the blueprint from which all turtle-kind are derived. If you want to test this theory, just try conducting an image search for 'turtle' and see how many green sea turtles come up, compared to loggerhead or hawksbills!
Hence most of us tend to assume that any image of a turtle will show an individual about 1.5m long, weighing around 190kg, because that's roughly how big those ubiquitous green sea turtles are. But A. ischyros is more closely related to extant leatherback turtles, which measure about 2.2m total length and weigh in at a whopping 700kg.
Bearing in mind that A. ischyros dwarfs even it's largest extant cousins with an approximate total body length of 4.6m and estimated weight of 2,200kg, visually describing this immensity in the open water is essential to conveying just how extraordinary this taxa is compared to its extant relatives.
All of which explains why I have opted in the end to depict this subject on dry land instead of in the open water. The best way to convey gigantism in an extinct subject is to place it in association with other subjects that the viewer can use as a yardstick. I considered using benthic substrate, corals, other marine animals, etc to do this in the blue, but again you have the same problem in that most people only have a notional concept of how long 'this' fish is compared to 'that' fish.**
On land, sourcing visual benchmarks that the audience can readily use as cues is a lot more straightforward. Surface water is notoriously difficult to scale up or down: historically this has made it a major headache for filmmakers, but a great scale index for artists. The same goes for sand and soil, which have unique properties when dry, damp, wet, sodden; and these are reproducible across a range of environments. Then there are plant species, invertebrates and larger flighted animals (which, with the exception of azhdarchid pterosaurs, are generally kept to a restrictive size by pesky physics).
All these elements make conveying scale much easier on land (at least when your primary audience is land-dwelling, air-breathing humans). Since all turtles need to lay their eggs on land, this seemed a good excuse/opportunity to show A. ischyros in a novel context.
So, having decided to show the subject on land, what might that environment look like? A little research showed that A. ischyros lived in the Late Cretaceous (Campanian) in what is now South Dakota. At this time, North America was divided in two by the Western Interior Seaway (WIS) - this explains why giant turtle remains can now be found in what is now the banks of the Cheyenne river, miles away from any sea! Knowing that the holotype was found in the Pierre Shale formation, I drew up a map of the WIS and plotted roughly where A. ischyros was found. I was then able to plot the locations of other species from around that time to work out some likely neighbours for our subject. These included Saurornitholestes langstoni, Icthyornis dispar and plant analogues included Juglandaceae, Rhoipteleaceae, Myricaceae and Betulaceae
I also knew that Claosaurus (Hadrosaurus affinis - this may be a nomen dubium, I haven't quite been able to find a definitive answer on this) was famously found in association with A. ischyros, leading experts to speculate that the hadrosaur died in the mouth of a river and got washed out to sea. This find has inspired artists to reconstruct scenes depicting nondescript hadrosaurs decaying in the ocean and being scavenged by sharks (incidentally I had considered this as a measure for scale to show A. ischyros in open water, but like I say, this had been done before). It seemed a shame to separate this pair after so many millions of years together, so again, this posed an opportunity to show Claosaurus at a different point in it's journey towards the open sea.
Having selected my line-up, it was time for the obligatory mug-shot! Taking approximate measurements for all the main subjects, I drew up a scale reference in preparation. This was also a chance to study the subjects, play around with integument (skin, scales, feathers and colours) and get a feeling for the scene arrangement and perspective angle I would need to adopt.
After scribbling a few options, I opted for the turtle laying her eggs on the beach, while curious scavengers look on in the hope that proceedings may offer a chance for a snack. Not there's any need, with a dead Claosaurus providing an ample buffet only a few metres away...
Having done this, I made a few more quick sketches of the environment in plan view, working out how far down the beach the carcass should be from the nest and how that might affect the perspective view from various angles.
Once this process was complete, there was nothing else left to do except get painting! Like I say, the final piece isn't quite finished yet, but it's near enough for my long-suffering and very patient client to include this preview in his article until it's published. Once that happens, we can finally unveil the finished illustration...
**The first time I actually saw a barracuda on a diving holiday in the Red Sea, I nearly spat out my regulator - I'd always assumed that they were "just a bit bigger" than pike! Again, this is becuase I'm English and the closest local species that we have here are European pike, in terms of body shape. The trouble was, in recording the similarities in shape between a Pike and a Barracuda, my brain had accidentally correlated size also, just because it had no other data to go on...until it actually saw a barracuda!
The article that this illustration accompanies is yet to be published, but here is a tantalysing sneak-preview of the work! I can't say any more now, but more details to come in 2020, I'm sure. In the meantime though, I just wanted to write a little about the thought processes behind the restoration work.
My initial instinct was to depict A. ischyros "in the blue" (in open water), but this poses specific technical challenges for a palaeoartist. The biggest consideration really is scale: it is difficult enough to convey scale underwater without visual references, but when dealing with extinct relatives of extant species the problem is compounded by the audience's assumptions about how big/small the subject "should" be.
This is all a matter of association: Put simply; in the mass-media world, we're used to seeing photogenic green sea turtles and anyone who has ever seen a nature documentary or visited an aquarium (or watched 'Finding Nemo'!) will have a notion of roughly how big they are and therefore how big they assume most turtles to be. Unless you already live in a turtle-rich environment, in which case you might assume olive ridley turtles to be representative of most turtles - it's all about what we're most used to seeing.
This is a key concept in semiotics and is tied in with Plato's theory of Ideas: that we all share a concept of the Ideal turtle - the blueprint from which all turtle-kind are derived. If you want to test this theory, just try conducting an image search for 'turtle' and see how many green sea turtles come up, compared to loggerhead or hawksbills!
Hence most of us tend to assume that any image of a turtle will show an individual about 1.5m long, weighing around 190kg, because that's roughly how big those ubiquitous green sea turtles are. But A. ischyros is more closely related to extant leatherback turtles, which measure about 2.2m total length and weigh in at a whopping 700kg.
Bearing in mind that A. ischyros dwarfs even it's largest extant cousins with an approximate total body length of 4.6m and estimated weight of 2,200kg, visually describing this immensity in the open water is essential to conveying just how extraordinary this taxa is compared to its extant relatives.
All of which explains why I have opted in the end to depict this subject on dry land instead of in the open water. The best way to convey gigantism in an extinct subject is to place it in association with other subjects that the viewer can use as a yardstick. I considered using benthic substrate, corals, other marine animals, etc to do this in the blue, but again you have the same problem in that most people only have a notional concept of how long 'this' fish is compared to 'that' fish.**
On land, sourcing visual benchmarks that the audience can readily use as cues is a lot more straightforward. Surface water is notoriously difficult to scale up or down: historically this has made it a major headache for filmmakers, but a great scale index for artists. The same goes for sand and soil, which have unique properties when dry, damp, wet, sodden; and these are reproducible across a range of environments. Then there are plant species, invertebrates and larger flighted animals (which, with the exception of azhdarchid pterosaurs, are generally kept to a restrictive size by pesky physics).
All these elements make conveying scale much easier on land (at least when your primary audience is land-dwelling, air-breathing humans). Since all turtles need to lay their eggs on land, this seemed a good excuse/opportunity to show A. ischyros in a novel context.
So, having decided to show the subject on land, what might that environment look like? A little research showed that A. ischyros lived in the Late Cretaceous (Campanian) in what is now South Dakota. At this time, North America was divided in two by the Western Interior Seaway (WIS) - this explains why giant turtle remains can now be found in what is now the banks of the Cheyenne river, miles away from any sea! Knowing that the holotype was found in the Pierre Shale formation, I drew up a map of the WIS and plotted roughly where A. ischyros was found. I was then able to plot the locations of other species from around that time to work out some likely neighbours for our subject. These included Saurornitholestes langstoni, Icthyornis dispar and plant analogues included Juglandaceae, Rhoipteleaceae, Myricaceae and Betulaceae
 |
| Map showing the present day locations where contemporaneous species were excavated. Empty circles indicate unconfirmed finds. Green box indicates choice of location for the restored environment. Copyright A V S Turner 2020 |
I also knew that Claosaurus (Hadrosaurus affinis - this may be a nomen dubium, I haven't quite been able to find a definitive answer on this) was famously found in association with A. ischyros, leading experts to speculate that the hadrosaur died in the mouth of a river and got washed out to sea. This find has inspired artists to reconstruct scenes depicting nondescript hadrosaurs decaying in the ocean and being scavenged by sharks (incidentally I had considered this as a measure for scale to show A. ischyros in open water, but like I say, this had been done before). It seemed a shame to separate this pair after so many millions of years together, so again, this posed an opportunity to show Claosaurus at a different point in it's journey towards the open sea.
Having selected my line-up, it was time for the obligatory mug-shot! Taking approximate measurements for all the main subjects, I drew up a scale reference in preparation. This was also a chance to study the subjects, play around with integument (skin, scales, feathers and colours) and get a feeling for the scene arrangement and perspective angle I would need to adopt.
 |
| Creating your own scale chart helps you get to grips with how subjects interact with one another in 3D space (a comparison not just of height and length, but weight, integument and mass). It's also an opportunity to play around with colours and patterns. Copyright A V S Turner 2020. |
After scribbling a few options, I opted for the turtle laying her eggs on the beach, while curious scavengers look on in the hope that proceedings may offer a chance for a snack. Not there's any need, with a dead Claosaurus providing an ample buffet only a few metres away...
Having done this, I made a few more quick sketches of the environment in plan view, working out how far down the beach the carcass should be from the nest and how that might affect the perspective view from various angles.
 |
| Drawing the environment from plan and side angles is essential for gauging depth, incline, the interaction between land, river and sea and assessing the placement of key subjects. |
Once this process was complete, there was nothing else left to do except get painting! Like I say, the final piece isn't quite finished yet, but it's near enough for my long-suffering and very patient client to include this preview in his article until it's published. Once that happens, we can finally unveil the finished illustration...
 |
| Copyright A V S Turner 2020 |
 |
| Copyright A V S Turner 2020 |
**The first time I actually saw a barracuda on a diving holiday in the Red Sea, I nearly spat out my regulator - I'd always assumed that they were "just a bit bigger" than pike! Again, this is becuase I'm English and the closest local species that we have here are European pike, in terms of body shape. The trouble was, in recording the similarities in shape between a Pike and a Barracuda, my brain had accidentally correlated size also, just because it had no other data to go on...until it actually saw a barracuda!
References:
Scheyer, Torsten & Sánchez-Villagra, Marcelo. (2007). Carapace bone
histology in the giant pleurodiran turtle Stupendemys geographicus: Phylogeny
and function. Acta Palaeontol Pol. 52.
Lichtig, Asher & Lucas, Spencer. (2015). CRETACEOUS TURTLES OF NEW
MEXICO. New Mexico Museum of Natural History Bulletin. 129.
Wieland Geo. R, Art. LVII Archelon ischyros, American Journal of
Science (Fourth series) Vol. II, No.12 Pg 399, 1896
TORSTEN M. SCHEYER, IGOR G. DANILOV, VLADIMIR B. SUKHANOV, ELENA V.
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Christopher & Meyer, Kyle & Carpenter, Scott & Erickson, J. Mark
& Matsunaga, Kelly & Smith, Selena & Sheldon, Nathan. (2016).
Temperature and salinity of the Late Cretaceous Western Interior Seaway.
Geology. 44. G38311.1. 10.1130/G38311.1.
Hallie J.Sims , Patrick S.Herendeen Richard Lupia Raymond A.Christopher Peter R.Crane , ‘Fossil flowers with Normapolles
pollen from the Upper Cretaceous of southeastern North America’, Review of Palaeobotany and Palynology, Volume 106, Issues 3–4, August 1999, Pages 131-151
Miller, I.M. & Johnson, Kirk & Kline, D.E. &
Nichols, D.J. & Barclay, Richard. (2013). A Late Campanian Flora from the
Kaiparowits Formation, southern Utah, and a brief overview of the widely
sampled but little-known Campanian vegetation of the Western Interior of North
America. At the Top of the Grand Staircase: The Late Cretaceous of southern
Utah. 107-131.
Lucas, Spencer & Sullivan, Robert & Lichtig, Asher
& Dalman, Sebastian & Jasinski, Steven. (2016). Late Cretaceous
dinosaur biogeography and endemism in the Western Interior basin, North
America: A critical re-evaluation. New Mexico Museum of Natural History and
Science Bulletin. 71. 195-213.
Horner, John R. “Upper Cretaceous
Dinosaurs from the Bearpaw Shale (Marine) of South-Central Montana with a
Checklist of Upper Cretaceous Dinosaur Remains from Marine Sediments in North
America.” Journal of Paleontology, vol. 53, no. 3, 1979, pp.
566–577. JSTOR, www.jstor.org/stable/1303998.
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