Angels, dinosaurs and artists’ impressions

We have long used optical telescopes to view distant objects, both living and non-living, making them easier to identify. More recently, technology has provided us with telescopes that record information transmitted over vast distances, allowing us to see distant stars, and even to look back in time as we view the expanding universe.

Similarly, optical microscopes reveal much more than we can see with the naked eye, and electron microscopes, of both scanning and transmission types, make very minute structures visible, although preparation methods require that care must be taken in interpreting what we see. Advances have also been made in the analysis of living and non-living materials that enable us to look at traces of organic chemicals from small samples and, using these approaches, we can analyse the composition of fragments and relate these to their origins. The commonplace use of an individual’s DNA in a blood stain is just one example.

Even armed with this information, we need expert analysis of what we see to make sense of it and this is aided by visual imagery, either generated by computer technologies, or by the hand of an artist. Artists’ impressions are invaluable in re-creating images of things that are no longer present and which we therefore have no chance of seeing. An example comes in the very numerous portrayals of religious scenes, where we are frequently shown images of Jesus, although we have no record of how He looked. The same goes for God, the disciples and all the other characters, as well as Heaven and Hell.

Other beings in religious paintings are given a physical presence that is unlikely or symbolic. The Holy Spirit is frequently depicted as a white dove, while angels have a characteristic appearance that we all recognise [1], with bird wings on a human body that also has arms (an example by Tiepolo is shown above). Taken as being real, these angels would not be able to fly, as the wings of birds have developed from the fore limbs of their reptile ancestors. With arms already present, the wings of angels, and the muscles to operate them, must be located quite differently on the body (I’m not suggesting here that angels do not exist, but that their physical form in paintings and sculpture means that they cannot fly using their wings). It’s an example of where artists’ impressions are very useful in creating images that subsequently have "reality".

Another world that fascinates us, and of which we have no direct knowledge, is that of dinosaurs. We’ve never seen a dinosaur (although there are some modern-day reptiles, like crocodiles, that give us some clues as to behaviour), so how do we know what they looked like and how they lived? We have evidence from which to work, unlike the images created of angels, where there is no fossil evidence. Bones, skin, muscle attachments, and feathers (where present) allow us to reconstruct dinosaurs and then put them into an imaginary landscape. We accept these images, and models based on them, because we believe what experts tell us (quite rightly?). The images are also informed by speculation. In Benton’s book on dinosaurs, with its catchy sub-title [2], we read that the discovery of pigment cells meant that “for the very first time, we knew the colour patterns of a dinosaur, and could use these insights to speculate about dinosaurian behaviour”. Can we really gain information about dinosaur behaviour from colour patterns? Perhaps we can. Later in the book, Benton describes the swimming of Stenopterygius, an ancient reptile from the Mesozoic: 

Stenopterygius swoops after a belemnite, an extinct relative of modern squid and octopus. The belemnite has a fleshy body and fins and swims backwards, just as modern cephalopods do. We know, too, that it has an ink sac, and so, like its modern relatives, likely squirts ink when alarmed, and zips off by blasting jets of water through its siphons. By the time the predator has recovered and snapped a few times at the ink cloud, the belemnite has long disappeared to safety. 

The Stenopterygius is not too fazed, as this is not an infrequent occurrence, and he lines up to chase another group of belemnites. 

Is the language a little flowery here? Admittedly, the book was written for a general audience, and books about dinosaurs sell well, but how critically do we, as members of the public, consider what is said by popularisers?

Further in Benton’s book [2], the dust cover of which shows Tupandactylus in flight (see above), we read this about head crests in bird-like dinosaurs: 

[It is] suggested that such prominent head crests and beaks sheathed in keratin as are seen in various dinosaurs and pterosaurs might have been photoluminescent.. ..[and] we can imagine the elaborate head crests of Tupandactylus flashing different colours at dusk, males and females perhaps showing different patterns, and putting on a spectacular in the crepuscular gloom. 

Please note the use of the words “suggested”, “imagine” and “perhaps” in this quote.

Moving images take artists’ impressions one step further and we are entertained not only by coloured images of landscapes, but also grunts and hisses from different dinosaurs. There is a good selection in the video linked in [3], (complete with an accompanying musical soundtrack to add tension to each scene). How much of this is supported by evidence? I accept that teeth marks on bones correspond to the dentition of certain dinosaurs, but the rest of it?

As we know, dinosaurs are not only important in palaeontology, but also in entertainment and in retailing. Go into any home with young children and you will find many dinosaur-related toys, pyjamas, t-shirts etc. and there is a popular fascination with mythological dinosaurs like the Loch Ness Monster and Sea Serpents. While there are artists’ impressions based on the sightings of the latter two, that is all we have to go on and the transformations of known dinosaur types that appear on clothing, or as toys, may be very far from the creatures that existed hundreds of millions of years ago. Steve Brusatte, reviewing Bentons’ book (see above) remarks that the images of dinosaurs it contains are real and can be used by media professionals, but is this so? Is there a point where palaeontologists can get a bit carried away with their liaison with the world of entertainment?

One important view of science is that it is based on falsifiable hypotheses and this is an approach that I have tried to follow in my research. However, falsifiable hypotheses are not possible with extinct animals (and plants) and, however ingenious our attempts, we are bound to make suppositions about the effects of time: we can design experiments that last hundreds of millions of years, but it is impossible to get the results. It means that palaeontology, including the study of dinosaur fossils, is a highly-informed guessing game, with some practitioners and artists going further into the world of imagination than others. Thus, the need for caution.

 

[1] Roger S. Wotton (in press) Birds and Christian Imagery. In Winged Worlds (eds. Olga Petri and Michael Guida). London, Routledge.

[2] Michael J. Benton (2021) Dinosaurs: New Visions of a Lost World. London, Thames & Hudson.

[3] https://www.youtube.com/watch?v=ZzXGSFVbVvU&t=847s&ab_channel=BBCEarth

Giant sea scorpions.. ..and other foods

In his book Why Not Eat Insects? Vincent M. Holt [1] does not confine himself to this group of invertebrates. In addition to remarks about slugs and snails, he also has this to say:

..Spiders have been relished as tid-bits, not only by uncivilized nations, but by Europeans of cultivation. For Reaumur tells of a young lady who was so fond of spiders that she never saw one without catching and eating it. Lalande, the French astronomer, had similar tastes; and Rosel speaks of a German who was in the habit of spreading spiders, like butter, upon his bread.

Spiders are chelicerates and, had Holt travelled to China, Thailand or Vietnam he would have been aware of other chelicerates, scorpions, being eaten, often as “street food”. Scorpions have a sting that is used to inject venom but, when cooked, the venom becomes denatured and the whole animal can be eaten. A common method of preparation is to line scorpions on skewers that can then be grilled (see below), or they can be stir fried. Those who eat scorpions compare their flavour to

that of crabs, or shrimps, and scorpions are rich in protein, so provide a readily available and nutritious food [2].

The largest chelicerates, the eurypterids, became extinct about 250 million years ago, so there is no possibility that they co-existed with humans, or close human ancestors. However, just as we like to imagine co-existing with reptilian dinosaurs (equally impossible), it is fun to think what our attitude to eurypterids would be should they still be present today.

In the image above, adapted from an illustration in a paper by Braddy, Poschmann and Tetlie [3] we see the body form of the eurypterid Jaekelopterus.  It is typical of the “sea scorpions” in having four pairs of walking legs, chelicerae (limbs with claws), a pair of paddles and a segmented body ending in a flattened extension. Two compound eyes are present and, in a comparative study of the fossilised remains of eurypterids of several types, it is concluded that Jaekelopterus was likely to be an active predator and that competition with more successful vertebrate types led to its extinction [4], alongside all the other eurypterids.

The location of fossils shows that Jaekelopterus lived in “marginal marine environments” [3] so, had these creatures survived to modern times, they would have been easily accessible to humans and, no doubt, would have been made extinct by human hunting. At this point, we need to consider the size of the animals: the scale bar in the illustration shows 1 metre, so specimens of Jaekelopterus were up to 2 metres long and thus substantially longer than the average human (2 metres being equivalent to 6 feet 6 inches). If their chelicerae were disabled, they would be easy to catch and they did not have the defensive sting present in today’s scorpions (they are not closely related).

Letting our imagination free, we can fantasise that Jaekelopterus, with its long and muscular body, would be good to eat, especially when prepared using the cooking skills of modern humans – “eurypterid thermidor” anyone? Nonsense of course, but what fascinating creatures they must have been, had we been able to observe them.

[1] Vincent M. Holt (1885) Why Not Eat Insects? Faringdon, E.W.Classey Ltd.

[2] http://survival-mastery.com/skills/scouting/eating-scorpions.html

[3] S. J. Braddy, M. Poschmann and O. E. Tetlie (2008) Giant claw reveals the largest ever arthropod. Biology Letters 4: 106-109.

[4] V. E. McCoy, J. C. Lamsdell, M. Poschmann, R. P. Anderson and D. E. G. Briggs (2015) All the better to see you with: eyes and claws reveal the evolution of divergent ecological roles in giant pterygotid eurypterids. Biology Letters 11: 2015.0564.