Boreal sea (Late cretaceous, Germany)
In the days before a global pandemic brought the world to a standstill, the Marine Reptiles Conference was set to take place in May 2020. With this date in mind, I hastened to prepare three entries to their photography and palaeoart competition in time, planning to submit two existing images of Archelon ischyros and a Jurassic Dorset scene (not that I'm currying favour or anything...) with an original piece for good measure.
But what to choose for a subject? Having recently worked on North America for my Archelon illustration, I fancied returning to mainland Europe for this piece. But I was still hooked on turtles, so an image that explored the evolution of marine turtles was in order, placing the likely time bracket somewhere around the early cretaceous.
My go-to resource for inspiration; the Palaeobiology Database (PBDB); provided a selection of promising taxa and their associated literature to start with. Subsequent searches for additional material from sources like researchGate, Academia and good ol' Wikipedia helped to narrow down the primary subject to Brancasaurus brancai: a magnificent plesiosaur from early cretaceous Germany. B. brancai is well-documented (being the most complete plesiosaurian taxon currently known from lower cretaceous Europe) and there is plenty of visual and written resource material available.
Furthermore, b. brancai was discovered in the Gronau clay pit in Westfalen, a site which has yielded many fossils from an intriguing marine/brackish environment which seems to have undergone phases of incursion and retreat from the Boreal sea to the north throughout the late cretaceous.
However, when it came to palaeoecology the only relevant papers cited in the most recent literature I could find were both published in German and in any case after a long fruitless search for digital copies I was forced to abandon that particular rabbit hole. So how to find details on early marine turtle species (or river turtles that might reasonably be woven into this intriguing lacustrine/marine environment)?
Again, I returned to the PBDB and open searches for turtles in north Germany in the buckeberg group. This line of enquiry led me to Toxochelys (Oertelia) gigantea - described in the literature as the oldest known true sea turtle (Karl et al, 2012). T. gigantea ticked all the boxes in being both from Lower Saxony (not too far from present-day Gronau) and found in Lower Aptian beds, so whilst not bang on the money, still a good fit in both time and place.
I was unable to narrow down other associated taxa beyond species-level, but early ray forms Spathobatis (with occurrences returned in the PBDB in the Late Jurassic in Germany and Early cretaceous in the UK) and Dasyatis (returning at least one occurrence in the Early Cretaceous UK) proved to be reasonable assumptions for the Gronau marine palaeofauna (the Boreal sea extended from modern Scandanavia down to Northern France and Germany).
Knowing that the periodically incurring Boreal sea created a warm shallow marine environment (connected to a lacustrine environment of brackish rivers and lakes), I conducted an image search for similar environments to inform the general composition, paying attention to visibility (scuba experience coming into play), the quality of warm and cold waters, turbulent and calm conditions, light, suspended particulates and plankton and the relationships between marine animals as they go about their daily lives.
I envisaged a rich, albeit turbulent and relatively cold environment (drawing on memories of diving off the coast of Tanzania during rainy season - the water isn't nearly as warm and balmy as you'd think!), where the shallow waters are misty with plant matter and sediments washed in from storm-swollen river deltas then churned up by surface activity, wave action and a morass of b. brancai as they abandon their normally solitary lifestyles to move briefly as one body in pursuit of a feeding bonanza some distance away (or maybe they're coming together in large numbers to mate, as Hammerhead sharks do?).
As the b. brancai make their way through the shallow waters, they are accompanied by other species eager to ride the wave of plenty whilst the going is good or else just hitch a free ride on the bow waves created by so many plesiosaurids moving in unison.
I originally painted the composition in monochrome, establishing composition and then form, adding colour only at the end. I still can't help but feel that ultimately I prefer the black and white version, but that might just be the influence of my childhood heroes J. Sibbick and A. Lee...?
I managed to finish and submit this piece just a couple of weeks before lockdown was announced in the UK and the event had to be rescheduled. As a result, the deadline for the competition was also extended, but even so I am pretty satisfied with the results and hope that this piece at least gives provides some pleasure to attendees and judges at the Marine Reptiles Conference when it eventually goes ahead in September.
Fingers crossed!
References:
Sachs et al. (2016), Reappraisal of Europe's most complete Early Cretaceous plesiosaurian: Brancasaurus brancai, Wegner, 1914 from the ``Wealden facies'' of Germany. PeerJ 4:e2813; DOI 10.7717/peerj.2813
H.V. Karl, S. Biermann & G. Tichy, "The oldest true sea turtle of the world, Oertelia gigantea (Oertel, 1914) n. gen. from the Aptian of Kastendamm near Hanover, Germany", Studia Palaeocheloniologica iv (Stud. Geol. Salmant. Vol. espec. 9), 2012: pp. 107-128, ISSN: 0211-8327
Sven Sachs, Jahn J. Hornung & Benjamin P. Kear (2017), "A new basal
elasmosaurid (Sauropterygia: Plesiosauria) from the Lower Cretaceous of Germany", Journal of
Vertebrate Paleontology, 37:4, e1301945, DOI: 10.1080/02724634.2017.1301945
Sachs S, Hornung JJ (2013) "Ankylosaur Remains from the Early Cretaceous (Valanginian) of Northwestern Germany". PLoS ONE 8(4): e60571. doi:10.1371/
journal.pone.0060571
Karl, Hans-Volker & Safi, Amtyaz. (2019). Desmemys bertelsmanni (Wegner 1911) (Testudines: Pleurosternidae) -a valid taxon of a mesozoic river turtle based on the rediscovery of type material from the Wealden fazies of North Rhine-Westphalia. 3. 45-61.
But what to choose for a subject? Having recently worked on North America for my Archelon illustration, I fancied returning to mainland Europe for this piece. But I was still hooked on turtles, so an image that explored the evolution of marine turtles was in order, placing the likely time bracket somewhere around the early cretaceous.
My go-to resource for inspiration; the Palaeobiology Database (PBDB); provided a selection of promising taxa and their associated literature to start with. Subsequent searches for additional material from sources like researchGate, Academia and good ol' Wikipedia helped to narrow down the primary subject to Brancasaurus brancai: a magnificent plesiosaur from early cretaceous Germany. B. brancai is well-documented (being the most complete plesiosaurian taxon currently known from lower cretaceous Europe) and there is plenty of visual and written resource material available.
Furthermore, b. brancai was discovered in the Gronau clay pit in Westfalen, a site which has yielded many fossils from an intriguing marine/brackish environment which seems to have undergone phases of incursion and retreat from the Boreal sea to the north throughout the late cretaceous.
However, when it came to palaeoecology the only relevant papers cited in the most recent literature I could find were both published in German and in any case after a long fruitless search for digital copies I was forced to abandon that particular rabbit hole. So how to find details on early marine turtle species (or river turtles that might reasonably be woven into this intriguing lacustrine/marine environment)?
Again, I returned to the PBDB and open searches for turtles in north Germany in the buckeberg group. This line of enquiry led me to Toxochelys (Oertelia) gigantea - described in the literature as the oldest known true sea turtle (Karl et al, 2012). T. gigantea ticked all the boxes in being both from Lower Saxony (not too far from present-day Gronau) and found in Lower Aptian beds, so whilst not bang on the money, still a good fit in both time and place.
I was unable to narrow down other associated taxa beyond species-level, but early ray forms Spathobatis (with occurrences returned in the PBDB in the Late Jurassic in Germany and Early cretaceous in the UK) and Dasyatis (returning at least one occurrence in the Early Cretaceous UK) proved to be reasonable assumptions for the Gronau marine palaeofauna (the Boreal sea extended from modern Scandanavia down to Northern France and Germany).
 |
| Studies for scale reference. Copyright A V S Turner 2020 |
Knowing that the periodically incurring Boreal sea created a warm shallow marine environment (connected to a lacustrine environment of brackish rivers and lakes), I conducted an image search for similar environments to inform the general composition, paying attention to visibility (scuba experience coming into play), the quality of warm and cold waters, turbulent and calm conditions, light, suspended particulates and plankton and the relationships between marine animals as they go about their daily lives.
I envisaged a rich, albeit turbulent and relatively cold environment (drawing on memories of diving off the coast of Tanzania during rainy season - the water isn't nearly as warm and balmy as you'd think!), where the shallow waters are misty with plant matter and sediments washed in from storm-swollen river deltas then churned up by surface activity, wave action and a morass of b. brancai as they abandon their normally solitary lifestyles to move briefly as one body in pursuit of a feeding bonanza some distance away (or maybe they're coming together in large numbers to mate, as Hammerhead sharks do?).
As the b. brancai make their way through the shallow waters, they are accompanied by other species eager to ride the wave of plenty whilst the going is good or else just hitch a free ride on the bow waves created by so many plesiosaurids moving in unison.
 |
| Monochrome version. Copyright A V S Turner 2020 |
I originally painted the composition in monochrome, establishing composition and then form, adding colour only at the end. I still can't help but feel that ultimately I prefer the black and white version, but that might just be the influence of my childhood heroes J. Sibbick and A. Lee...?
 |
| The completed reconstruction with colour. Copyright A V S Turner 2020 |
I managed to finish and submit this piece just a couple of weeks before lockdown was announced in the UK and the event had to be rescheduled. As a result, the deadline for the competition was also extended, but even so I am pretty satisfied with the results and hope that this piece at least gives provides some pleasure to attendees and judges at the Marine Reptiles Conference when it eventually goes ahead in September.
Fingers crossed!
References:
Sachs et al. (2016), Reappraisal of Europe's most complete Early Cretaceous plesiosaurian: Brancasaurus brancai, Wegner, 1914 from the ``Wealden facies'' of Germany. PeerJ 4:e2813; DOI 10.7717/peerj.2813
H.V. Karl, S. Biermann & G. Tichy, "The oldest true sea turtle of the world, Oertelia gigantea (Oertel, 1914) n. gen. from the Aptian of Kastendamm near Hanover, Germany", Studia Palaeocheloniologica iv (Stud. Geol. Salmant. Vol. espec. 9), 2012: pp. 107-128, ISSN: 0211-8327
Sven Sachs, Jahn J. Hornung & Benjamin P. Kear (2017), "A new basal
elasmosaurid (Sauropterygia: Plesiosauria) from the Lower Cretaceous of Germany", Journal of
Vertebrate Paleontology, 37:4, e1301945, DOI: 10.1080/02724634.2017.1301945
Sachs S, Hornung JJ (2013) "Ankylosaur Remains from the Early Cretaceous (Valanginian) of Northwestern Germany". PLoS ONE 8(4): e60571. doi:10.1371/
journal.pone.0060571
Karl, Hans-Volker & Safi, Amtyaz. (2019). Desmemys bertelsmanni (Wegner 1911) (Testudines: Pleurosternidae) -a valid taxon of a mesozoic river turtle based on the rediscovery of type material from the Wealden fazies of North Rhine-Westphalia. 3. 45-61.
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