Paleoart accuracy

Today I’m posting my first major look at paleoart accuracy here. Recently, I have completed some drawings and sketches of dinosaurs, like Spinosaurus aegyptiacus, and my first non-dinosaurian. My knowledge of anatomical features that affect paleoart comes mainly from the english wiki dinosaur image review team, originally run by Matt Martyniuk, with the occasional comment from Heinrich Mallison, but now mostly reviewed by myself and Michael Bech. I learned mostly from Michael, who himseld was taught by Matt. Below is a copy-pasted list of anatomical features of dinosaurs that render many drawings inaccurate, from the WikiProject Dinosaurs review page. Feel free to comment on or mention more features, especially if you are an expert on a topic. New features or addendums will be added in underlined text.

General guidelines for dinosaurs

  • When restoring the eye of a dinosaur, always make sure to make the cornea fits within the inner diameter of the sclerotic ring, if such is not present in the skeletal restoration used as reference, use one of a related genus for reference instead.[1] Only the cornea should be visible.
    • As an addendum, when you restore the eye of a non-avian dinosaur, use birds and crocodylians as guidelines. As such, restoring dinosaurs with pupils facing away from where the head is positioned is most likely inaccurate; although some birds (like the great cormorant) can move their eyes independently of the head, this is not the norm for birds and as such is unlikely to have been a norm in other dinosaurs. This means that when the orbit is facing perpendicular to your drawing, the pupil should be in the centre of the eye.
  • The nostril should always be placed at the front end of the bony naris.[2] Exceptions to this are sauropods, which should have the nostril at the upper tip of the snout, not the naris.
  • Beaks, horns, spikes and claws should be restored longer than they appear from the bones, as these were covered and extended by keratinHowever, the thickness of the keratin is variable, try to layer it in theropods so that an even amount over the entire bone will come to a sharp point, especially with claws if in life they were used for defence/attacking.
  • The colours are not known for dinosaurs preserved without feathers, but in general, large modern animals usually have drab colours, whereas small animals can have more vivid colours. Also consider colours that would be good for camouflage. This likely is the reverse. Large sauropods would have been to big for camouflage to be affective, while predatory animas hunting prey around the same size as themselves would need to blend in to get close enough to strike. Herbivorous of insectivorous dinosaurs that are small would likely be fast, and are more probable to have used colours in a display.
  • Dinosaurs that are known to have lived within different time periods and geographic ranges should not be restored as if living together. Likewise, plants and other environmental features present in the restoration should match fossil evidence. For example, dinosaurs from the Triassic or Jurassic should not be depicted walking on grass, which did not exist at that time.
  • Dinosaurs should not be depicted with external genitals, but with crocodile and birdlike cloaca.
  • Dinosaurs should be shown with fleshy pads underneath their feet and toes, and on their hands and fingers, these should match the pattern seen on tracks known to belong to related animals.[3] These fleshy pads shouldn’t be shown on Spinosaurus, where the feet were webbed and adapted for an aquatic lifestyle.
  • No dinosaurs could cross the radius and ulna arm bones, making their ability to rotate their hands very limited/impossible.[4]
  • Be sure that quadrupedal dinosaurs are shown with their legs in the right order.[5] This is sort of vague, but I’m not sure how to explain it.

Guidelines for theropods

  • No theropod should be restored with more than three inner claws on their hands, regardless of finger count. Fourth and fifth fingers should always remain clawless.
  • They should not have pronated “bunny-style” hands.[6] However, their hands could still face close to the horizontal, but more research needs to be done on specific groups.
  • They should not be reconstructed with overly flexed tails, and dromaeosaurs had very stiff tails, supported by entwined bony processes.[7]
  • Coelurosaurian theropods should be depicted with protofeathers if more primitive than oviraptorosaurs, and contour feathers if as derived or more than them. Taxa outside coelurosauria can also be shown with protofeathers.
  • The primary feathers of maniraptoran wings should grow from the second finger, not from the arm, as is often shown.
  • Leg “wings” are basal to deinonychosaurs, so keep this in mind when restoring one.
  • Protofeathers should not be coloured blue, green or purple.[8]
  • All maniraptorans should have contour feathers, not protofeathers anywhere on their bodies.

Guidelines for sauropodomorphs

  • If nothing indicates otherwise, prosauropods should be depicted as bipedal, with non-pronated hands. The hind legs should be depicted as heavy enough to support the weight of the animal.[9] Melanorosaurids were likely quadrupedal.
  • Like theropods, prosauropods had no more than three claws, all on the inner three fingers.
  • Sauropods should not be restored with more than one inner claw on their front legs. Titanosaurs had no fingers at all.
  • Sauropods should not be reconstructed as chewing food, as their dentition is unlike those of hadrosaurs and ceratopsids (which, with their batteries of teeth and robust jaw musculature, probably could chew in a vertical, scissor-like motion). Gastroliths also indicate that sauropods did not chew their food manually, but ground it in the stomach with stones.

Guidelines for thyreophorans

  • Ankylosaurs should be restored with cheeks.
  • The digits of their hands were arranged in a columnar, sauropod-like fashion.[10]
  • Stegosaurian thagomizers should be held parallel to the ground, with the spikes projecting horizontally from the tail.

Guidelines for ornithopods

  • The three central fingers of iguanodonts and hadrosaurs should be encased in a single hooflike sheath.
  • Hadrosaurs had very inflexible tails, stiffened by bony tendons, so the tails could only be moved slightly to the sides, but not up and down.
  • Skin impressions as well as “mummies” have been found of hadrosaurs; use these as reference when restoring the skin of hadrosaurs and related ornithopods.
  • Hadrosaurs and other ornithopods could not pronate their hands.[11] The pronation of ornithopods confuses me, so I can’t explain further.
  • All primitive iguanodonts should have a thumb-spike, although variable in size.

Guidelines for ceratopsians

  • Ceratopsians may be restored with bristles on their tails, as the primitive ceratopsian Psittacosaurus has been shown to have such structures.
  • They have five fingers on their hands. Only the inner three should be shown with claws.[12]
  • Ceratopsians could not pronate their hands.[13] I don’t understand the hand anatomy of ceratopsians, so I cannot explain more.

Now with all this text, this post needs some images, so here are my latest four drawings, guess what they are.

ForstercooperiaSpinosaurus aegyptiacusEuropeltaAchillobator.jpg


About ijreid

I am an amateur palaeontologist thats hobbies include studying extinct amniotes, specifically dinosaurs, birds, and mammals. Occasionally, I focus my time on detailed and accurate illustrations of dinosaurs, and I have completed drawings of Dysalotosaurus, Micropachycephalosaurus, Zhuchengtyrannus, Troodon, Eotyrannus, Europelta, and Achillobator. I do not believe in copyrights, and think that the world would be better if everything was open access.
This entry was posted in Anatomy and tagged , , . Bookmark the permalink.

One Response to Paleoart accuracy

  1. jrabdale says:

    I like all of the info that you have listed here, and I’ll certainly put it to good use from now on. My artistic skills are evolving, just as life in general does.


Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s