Ecology of Colour (Zoology for paleoartists, part III)

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colouration, dinosaurs, sexual selection

Mother Tianyulong is not happy. But what are each of her colour patterns for?

In the first two parts of this series, we went through different pigments that make up the rainbow of living bird colour, and discussed which of them were probably present on the skins and feathers of non-extinct dinosaurs.

In the end, we concluded that almost any colour, from black to white and orange to green, is possible. However, we paid no attention to what kind of colours are ecologically plausible. This article goes through different evolutionary pressures that shape animal colour – camouflage, impressing mates, keeping feathers intact.

Whole books and life’s works have been spent on the subject, so this article will necessarily be only a brief introduction. I will mostly use dinosaurs (both non-avian and living) as examples, but much of this also applies to other groups of extinct animals.

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A Rainbow of Dinosaurs (Zoology for paleoartists, part II)

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colouration, dinosaurs, pigments

In the first part of this series, we went through bird colours formed by melanosomes and structural properties of their skin and feathers. These mechanisms produce blacks and greys, browns, iridescences, blues and purples. These are also the only colours that can be at the moment partially deciphered from well-preserved fossils.

However, that is not even close to the full rainbow of living birds, and unlikely was that for non-avian dinosaurs either. In this article, we’ll go through other mechanisms living birds use to produce colour, and speculate how likely each of them would be in ancient non-avian species.

How birds get their color? (Zoology for paleoartists, part I)

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colouration, dinosaurs, pigments

At the moment, only a small subset of colour-producing mechanisms present in birds can be detected from fossils. What is a paleoartist to do?

One of the most fascinating aspects of paleoart is the creation of colour palettes for animals long gone. It is an interesting exercise: the end product is almost certainly wrong, as chancing upon the exact right colouration is very much comparable to winning the lottery. The goal of most paleoart is to make reconstructions that are wrong in a way that is plausible, interesting, and aesthetically pleasing.

Even the recent advances in deciphering colours from fossils have not changed everything. At the moment they only apply to a small number of dinosaurian taxa, and even within those, to a small subset of colour-producing pigments.

There are lots of ways to approach the problem of colour. Some paleoartists copy and paste the patterns of living animals on top of ancient ones almost directly. Others study animal colouring and ecology and incorporate ideas and principles to their art. Still others are most concerned with making beautiful art pieces with colours that fit together.

Whichever the approach, everyone benefits from understanding the basics of animal colouring. Where do the colours of living animals come from? What do we know about which pigments and structures were possible for extinct groups? For non-avian dinosaurs, the best point of comparison are living birds, followed by crocodylians. Studying mammals also has something to offer.

Dinosaurs of the Taiga (botany for paleoartists part VII)

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cretaceous, north slope, paleobotany, prince creek formation

Ugrunaaluk kuukpikensis in winter. Illustration for the newspaper Helsingin Sanomat.

Back at the time, many people considered the Mesozoic world a constant tropical hothouse, with little variation on climate. Dinosaurs were portrayed as great lizards that required tropical climates to thrive.

Arctic dinosaurs give one more killing blow to that already pretty old-fashioned concept. They lived in a cold climate well beyond the Arctic circle – and apparently thrived. But what was their world like?

I recently wrote a newspaper article on the newly described Alaskan hadrosaur Ugrunaaluk kuukpikensis. For that, I read a bunch of papers about the flora and climate or Cretaceous Arctic. I also contacted paleoclimatologist Carla Tomsich from the University of Alaska, who turned out to be an incredibly helpful and nice person. Here’s what I learned about Ugrunaaluk‘s world.

Old Trees are Old Friends (botany for paleoartists part VI)

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cretaceous, dawn cypress, delta cypress, ecology, ginkgo, katsura, maidenhair tree, platan, succession, sycamore

In today’s world, habitats disturbed by landslides, shifting rivers, forest fires, or humans, are rapidly taken up by pioneer plants, whose motto seems to be ‘live fast, die young’. The pioneers, such as fireweed, willows, and dandelions, flourish for only a few years before being pushed away by species that represent more mature phases of succession. Here in Finland, that usually means first birches and rowens, and after a few decades, thick dark forests of spruce.

In the time of the dinosaurs, things were slightly different.

Things I Saw in Madeira (botany for paleoartists part V)

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conifers, cycads, ferns, flowering plants, fossil plants, laurisilva, Madeira, mosses

Cycad hybrid Encephalartos horridus x lehmanni.

I have been mulling on an article on ginkgoes and other pioneer plants of the Cretaceous since October, but I still haven’t gotten around writing it. In the meanwhile, however, I spent Christmas in Madeira (for those uninitiated, it’s a tiny oceanic island off the coast of Morocco) and saw heaps of interesting ancient plants in life. Here’s a small pictorial tour to act as inspiration and reference.

Flora in the Time of Chasmosaurs (botany for paleoartists, part IV)

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dinosaur park formation, dinosaur provincial park, flowering plants, paleobotany, paleoclimate

Dinosaur Provincial Park is a fossil site spanning the time approximately between 76,6-74,8 million years ago, in Alberta, Canada. It’s a famous site with well-known dinosaurs. There are ceratopsians such as Chasmosaurus and Styracosaurus, hadrosaurs such as Corythosaurus and ankylosaurs like Edmontonia. Most famously, the area was haunted by great tyrannosaurs Daspletosaurus and Gorgosaurus.

Less famously, the site also has a fairly good record of fossil plants. At the time, the area was a flat, forested plain with dozens of sediment-laden rivers slowly meandering towards the Western Interior Seaway. The climate was warm temperate, and plenty of ponds and swamps dotted the landscape. This gorgeous and accurate painting is by Julius Csotonyi, from this PLOS One paper, with Creative Commons license.

Let’s now take a closer look at the variety of plants that flourished in the area and fed the dinosaurs.

On Grasses and Not Exactly Grasses (botany for paleoartists part III)

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grasses, paleobotany, poaceae

Illustrating dinosaurs grazing on grasslands is considered a cardinal error in paleoart. In part, this is justified. In part, not so much.

True grasses of the family Poaecae are a late product of plant evolution, but not as late as was previously thought. They seem to have existed as early as Late Cretaceous, according to some grass-like phytoliths found in 66-million-year-old coprolite, or dinosaur dung, and pollen record on several continents.

However, the vast grasslands known today have not existed for long. For 25 million years or so after the demise of non-avian dinosaurs, grasses account for less than 1 % of all pollen in the fossil record. Grasslands only appeared after the global rainforests of Eocene Epoch receded, making way to dry-adapted plants like grasses. Evidence of large grass-dominated ecosystems appears by the Early Miocene, some 20 million years ago. (photo: Miroslav Duchacek/Wikimedia Commons)

Despite the lack of actual grasses, there is a number of other, older plants that look very grass-like even though they’re not closely related. Paleoartists often avoid depicting anything that looks remotely like a grass, but the general shape – thin leaves and/or fronds standing more or less upright, with reproductive structures on top – is fairly common and seems to work for both xeric and mesic plants.

Fruit for the Dinosaurs (botany for paleoartists part II)

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conifers, cycads, ginkgo, gnetophyta

Flowering plants, including the kinds we associate with edible fruit and berries, only diversified near the end of the time of dinosaurs. For most of the Mesozoic, anything like avocadoes and grapes, blackberries or raspberries simply did not exist. Accordingly, paleoartists don’t depict these in their Mesozoic scenes.

But this does not mean Mesozoic animals didn’t eat sweet fruit-like plant parts, as flowering plants are not the only ones that produce them (photo: Juniperus communis, Sarah Gregg/Flickr).

Not All Ferns Look Like Ferns (botany for paleoartists part I)

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ferns, fossil plants

I was recently (and rather persistently) informed that paleoartists might find this sort of articles useful: easily approachable pieces about botany as relevant to paleoart. Most paleoartists are, understandably, primarily interested in prehistoric animals. Unfortunately animals don’t often live on lifeless deserts, so depicting vegetation tends to be essential part of the trade.

Full reconstructions of prehistoric plants or even photographs of plant fossils are often frustratingly hard to find, resulting in quite stereotypical vegetation in much of paleoart. Some ginkgoes, some monkey puzzle trees, cycads that almost always tend to look like Cycas revoluta. And, of course, ferns.

But not all ferns have the nondescript green, bipinnate leaves like the ones we all think of when hearing the word ‘fern’. Paleoartists have a lot more choice than that, even when looking just at the modern diversity. Before the onslaught of hyper-diverse, overly competitive flowering plants and drying climates, ferns were probably vastly more diverse than now. Today’s ferns are pushed into marginal habitats, mostly damp and dark places like forest undergrowth layers (photo: Platycerium elephantotis in Uganda, Bernard Dupont/Flickr).

Still, ferns show a remarkable diversity of leaf shapes.