Late Cretaceous North America, Judith River Formation 75 Ma.
Named from a single tooth in 1856, for many years this enigmatic little dinosaur defied exact classification, being considered first a lizard, then a megalosaurid and even a pachycephalosaur, its unusual tooth morphology consistent with an omnivorous diet. Since then it has been firmly established that Troodon formosus was in fact a small theropod dinosaur of a lineage extremely close to birds. Subsequent fossil discoveries have shown that Troodon possessed large eyes with reasonable depth perception, ideal for nocturnal hunting. With feathers, and a small sickle claw on the second toe of each foot, it was similar to its close relatives the dromaeosaurids.
The moist coastal forests of Late Cretaceous North America would have looked superficially similar to many forests today. Conifers (Taxoidium sp.) give way to broadleaf trees Ficus (figs) and Fagus (beech). Epiphytes grow on fallen debris, ferns and cycads grow as understorey plants. Many angiosperm varieties grow alongside. Palms, laurels and Erlingdorfia (sycamore) are illustrated.
At the time of preparing this painting in 1995/6, used as a poster by the Dinosaur Society UK, the idea of feathered dinosaurs was still in its infancy, indeed, despite a connection proposed between dinosaurs and birds as far back as the Victorian era, the only feathered dinosaur known at the time was Archaeopteryx, considered then, as it is now, to be closer to a bird than a dinosaur.
In 1996 the discovery was made of Sinosauropteryx, from sediments in China, the small dinosaur clearly displaying evidence of a primitive feather/filament-like integument.
Important as this was, the specimen was new to science and was only then being described, and it alone did not prove that all small theropod dinosaurs possessed feathers. I believed at the time as I do now, my duty to be to reconstruct the animal I was depicting based on known facts, not unproven speculation.
That was twenty years ago, and a lot has happened since then. Geopolitical changes have opened up parts of the world previously closed to exploration, while better techniques in collecting and preparation have allowed the recovery of more delicate fossil details. Then, in 1998, an important discovery was made showing a clear indication of the attachment points of feathers on the ulna of Velociraptor, a close relative of Troodon.
Today it is widely accepted that the smaller Coelurosaurian dinosaurs were feathered to some degree. The obvious connection between birds and dinosaurs has been firmly established, and in some very rare cases, incredible advances in technology have allowed scientists to even determine the colour of some of these dinosaurs’ feathers.
This being so, I decided to update my original illustration, repainting and replacing the original, now outdated depiction of Troodon, as first published, with a more accurate, updated, feathered animal, better capturing, I hope, this small dinosaur’s close connection to birds.
Acrylic painting 1996 Updated 2018
Middle Jurassic Tiouraren Formation, Niger, North Africa 162 Ma.
First described in 1994, Afrovenator abakensis is known from the Middle Jurassic deposits of Niger, North Africa. At eight metres in length, Afrovenator was a large terrestrial carnivore, but classifying its position within the theropod family tree has proved problematic. Today most researchers consider it to be a Megalosaur more closely related to the European Eustreptospondylus, than the allosaurs that would later replace it.
During the Middle Jurassic period, the giant supercontinent of Pangaea was in the process of dividing in two, Laurasia to the north and Gondwana, to the south, the embryonic Atlantic Ocean forming between them. Climates are generally considered to have been tropical with characteristic Jurassic flora distributed world wide.
In this painting, the tree-fern Coniopteris dominates the wet forest understory. Pachypteris, a Pteridosperm, along with horsetails and conifer foliage of an Elatocladus type are illustrated.
Late Jurassic North America, Morrison Formation 155-150 Ma.
Allosaurs were the top predators of the Jurassic, averaging 8.5 – 9.5 metres in length. They would have preyed on the herds of giant sauropods that browsed the Jurassic floodplains. New studies indicate these dinosaurs were pack hunters and would have taken turns at slashing and tearing off chunks of meat from the hides of living animals. Its quite possible that dinosaurs like Diplodocus regularly displayed long wounds in their flanks resulting from this form of predation.
Late Triassic North America, Upper Chinle Formation. 200 Ma.
200 million years ago, in the Late Triassic period, the Upper Chinle Formation, in the Painted Desert portion of Petrified Forest National Park, was a very different place from today. It was an extensive floodplain of swamps, forests, lakes and braided streams, where heavy rains and periodic flooding would swell rivers and undermine the trees, washing their broken trunks into vast log jams, burying them beneath silts and mud, rich in iron oxide, limonite and manganese whose brightly coloured compounds today give the Painted Desert its name, while silicon dioxide, dissolved from fine volcanic ash, mineralised and preserved these fallen trees.
Araucarioxylon is the generic name given to these extinct conifers. It means ‘wood of the Araucaria’ but this is misleading, as they were not closely related to the Araucariaceae. In fact Araucarioxylon probably resembled the giant coastal redwoods of California, with crowns of lacy, umbrella-like foliage.
Coelophysis bauri was one of several early dinosaur species inhabiting the Chinle forests and perhaps, like birds today, Coelophysis formed flocks, or possibly environmental stresses like drought caused them to gather in larger concentrations, where evaporating streams offered them a source of both food and water. There, surprised by flash flooding, whole groups of these animals were washed away to be fossilised in a mass grave.
The excellent preservation of plant and animal material from the Chinle Formation, and the abundance of fossil remains, make it one of the best ‘windows’ into the Late Triassic world yet discovered in the Western Hemisphere.
Dromaeosaurus albertensis Late
Cretaceous North America, Hell Creek Formation 67-65 Ma.
At the end of the Cretaceous the lowland forests of North America displayed many modern characteristics. Large conifers (Taxoidium, Auracarian. sp) remained, growing alongside the now more abundant angiosperms. Palms, laurels, sycamores, figs and oaks were common and flourished in these subtropical deltas.
Dromaeosaurs were light agile hunters, and like many other small predators found the reptiles and small mammals that inhabited these forests a reliable source of food.
Although the affinity between birds and theropod dinosaurs had been proposed since the Victorian era, it was only with the discovery of Sinosauropteryx in 1996 and the identification of quill knobs on the ulna of a Velociraptor in 2007 that palaeontologists could say for certain these animals would have been feathered. This illustration was prepared prior to these fossil discoveries.
Stegosaurus & Ornitholestes
Late Jurassic North America, Morrison Formation150 Ma.
The sediments of the Morrison formation of the Western United States represent a flat semi-arid landscape prone to seasonal flooding. It is depicted here following heavy rain, the baked clay soil has yet to absorb freestanding water. Conifers with Brachyphyllum and Podocarp type foliage shadow Marattia treeferns. Osmunopsis and Gleichenites ferns form an understory.
A small theropod Ornitholestes hermanni takes shelter at the forest margin while Stegosaurus stenops and Camptosaurus dispar occupy the middle ground and distance respectively.
Ornitholestes is depicted in this 1998 illustration as possessing a small nasal horn , it is now believed this feature is incorrect.
Camarasaurs at the Waterhole
Late Jurassic North America, Morrison Formation 152 Ma.
Proto-penguins take the plunge
Waipara Greensand, Middle Palaeocene 62 Ma.
Waimanu, was a flightless, aquatic Neoave from the middle palaeocene epoch. Two species have been collected, W. tuatahi from sediments dated between 58 – 60Ma, and W. manneringi 62Ma, slightly older but less complete. Both are recognised as being basal members of the phylogenetic group the Sphenisciformes, a taxonomic order containing all modern penguins.
Evolving soon after the Cretaceous – Paleogene extinction event, Waimanu’s body morphology already exhibits the fusiform streamlined anatomy required to hunt with agility underwater, indicating that the evolution of penguins most certainly started in the Late Cretaceous, but unlike their more specialised descendants, Waimanu possessed a curious mixture of primitive and derived characteristics. Standing upright at 80 cm tall, on short legs, Waimanu would have superficially looked like a modern penguin, its terrestrial locomotion similar. However, its forelimbs, although reduced for manoeuvrability underwater, lacked the rigid elbows and compressed profile which enable modern penguin wings to cut through water like a flipper.
Palaeontologists speculate that Waimanu may have swum and hunted in a manner similar to its modern close genetic relative the Loon, propelling itself through water with its feet rather than its wings.
Soft tissues have not been preserved, but Waimanu fossils were deposited in a marine environment and it is reasonable to expect that it possessed waterproof plumage similar to extant penguins, and expressing a high degree of countershading.
Waimanu evolved into a warm world lacking many of the dangerous terrestrial and aquatic predators of the late Cretaceous and, like many of the birds in New Zealand today, responded to an absence of threat by losing the power of flight. It took to water, and exploited one of the abundant ecological niches vacated by the mass extinction of the large marine reptiles and many species of shark in the world’s oceans.
Tropeognathus & Pagiophyllum foliage
Early Cretaceous South America, Santana Formation 112-108 Ma.
Tropeognathus, a large anhanguerid pterosaur glides through the cool coastal Auracarian forests of what will one day become Brazil.
Araucarian conifers with Pagiophyllum-type foliage based on Araucaria bidwilli, form the forest canopy. Although still extant in parts of South America, these primitive conifers once dominated forests across the world.
Tropeognathus probably fed on fish and other aquatic animals it could take from the surface of the ocean, perhaps feeding in a manner similar to a Pelican. Its remains and that of its relatives have been found in Europe and South America. It was a giant animal with a wing span approx. six meters across
Etching & graphite drawing
Lub Score Footprint Slab,
‘Feeding on the Flats’
A remarkable slab containing many small theropod footprints found on the Isle of Skye, Scotland, records, perhaps for the first time, parental behaviour seen between a parent dinosaur and its young.
Unlike fossil bones, preserved after an animals death, dinosaur trackways, recorded in life, can reveal a remarkable amount about the animal(s) that made made them, pace, gait, stride length, orientation, sociability, whether an organism walked on two feet, four feet, on the flats of its feet, or its toes, opening for us a brief window in an animals life, otherwise lost to the vast history of time.
In the case of the Lub Score slab, we see the tridacyl footprint impressions of several small dinosaurs interacting, an individual of perhaps 3 meters in length and smaller dinosaurs, apparently of the same species, engaged in what palaeontologist interpret to be a family group.
With the link between coelurosaurian dinosaurs and birds firmly established, it is not hard to envisage the long distant ancestors of birds engaged in similar activities we are familiar with today; a parent feeding her young, ‘chicks’ squabbling perhaps for some morsel she will regurgitate, plucked earlier that day from the jurassic shoreline.
From footprints alone, the author of these enigmatic impressions cannot be identified with certainty, however, there are limited potential candidates for who these track makers might have been, and with bone fragments and teeth also recovered from Skye, and a skull from Middle Jurassic deposits in England, palaeontologist believe we are looking at an amimal similar to Proceratosaurus, an early Tyrannosaur ancestor.
Middle Jurassic Duntulm Formation, Isle of Skye Scotland 170-166 Ma.
Although now situated at the north-west corner of Europe, Scotland has not always been positioned so, having gradually moved from the equator to where it now resides over a period of millions of years. During the Middle Jurassic period Scotland was a lot further south, enjoyed a tropical climate and was located in the heart of a super-continent called Laurasia, now fragmented to form North America, Europe and Asia.
The Isle of Skye is one of the best places in the world to discover dinosaurs from the Middle Jurassic period, and researches have recently identified several trackways of a large primitive sauropod dinosaur that waded in the shallow waters of a lagoon, some 170 million years ago.
Cetiosaurus remains are better known from deposits in England, but this is a likely candidate for the dinosaurs that made the enigmatic impressions on the Scottish beach and as its name suggests it was proportioned somewhat like a terrestrial whale.
Proceratosaurus, foreground, was a small theropod dinosaur ancestral to the later tyrannosaurs and almost certainly had feathers. Here it is depicted taking interest in a horseshoe crab and other detritus washed up on the Jurassic shoreline.
Late Triassic – Early Jurassic
North America 203-196 Ma.
Of all the many theropod dinosaurs collected worldwide, Coelophysis bauri from North America is probably one of the better understood. It appeared early in the story of dinosaur evolution, demonstrating a successful bipedal body plan that would advantage theropod dinosaurs over their more diverse archosauriform contemporaries and ultimately give rise to successful radiations of larger carnivorous dinosaurs beyond the late Triassic.
Although discovered in North America, Coelophysis and other coelophysoid dinosaurs weren’t limited to this single geographical location. Indeed, with the super continent Pangaea still intact through much of their evolution, coelophysoid remains have been discovered in both northern and southern hemispheres, with another well represented species, C. rhodesiensis recognised from southern Africa. Other fossils have been found in France, Germany and even Antarctica and a probable Coelophysis-like tooth was found on the Isle of Skye in Scotland.
Coelophysis bauri was a lightly-built dinosaur averaging lengths of three metres, and is known from literally hundreds of skeletons, having been excavated in large concentrations at a mass grave-site in Arizona. This prompted palaeontologists to speculate that Coelophysis was a gregarious animal and travelled in packs, perhaps hunting together to subdue larger prey; this is a possible hypothesis, although to date, no evidence to support this behaviour exists. It is probable also that environmental forces, such as a drought or flash flood or indeed dietary interests like fishing, may have concentrated these animals together, and this idea is further supported within the Coelopyhsis anatomy by the presence of kinked snouts and conical dentition in the premaxilla and tip of the lower mandible, ideal for picking up small or slippery prey.
Another interesting observation difficult to make with many dinosaurs, but thought possible with Coelophysis due to the abundance of fossil remains, is the probability of demonstrating sexual dimorphism; there being both gracile and a robust forms present in equal numbers at the mass gravesite, however, more recently, research would suggest this particular dinosaur displayed great variation in its adult and juvenile growth rates and the idea of obvious sexual dimorphism has been rejected pending more compelling evidence.
In terms of life appearance, Coelophysis was a primitive dinosaur, retaining four digits on its hand, short arms, short legs and a reptilian-like ribcage; yet had already evolved several bird-like features, including a pneumatic skeleton. Coelophysis evolved during the late Triassic era when the world’s average temperatures were higher than today, yet we cannot say for certain whether this small, primitive dinosaur had an armoured, scaly or possibly an early protofeather integument.
Ink & graphite drawing.
Late Jurassic North America, Morrison Formation
Ceratosaurus nasicornis was a formidable predator that stalked the forests of the Late Jurassic Morrison formation. Growing to lengths of six metres, it was smaller and somewhat scarcer in the fossil record than its contemporary, Allosaurus, and possibly favoured a different environment and lifestyle from the larger carnivore. Unusually for a theropod dinosaur Ceratosaurus possessed a bony nasal horn that it may have used in jousting matches with rivals of its own species, or more likely as a form of sexual display.
Sphenodonts are today confined to one species, the Tuatara from New Zealand, but during the Mesozoic era they were widespread. Similar to lizards in general appearance and body plan they were in fact part of a different family of animals.
Araucarias are primitive coniferous trees. Once abundant in the Mesozoic, they are now confined to a few species native to the southern hemisphere.
Ink & graphite drawing.
Styxosaurus & Ichthyodectes
Late Cretaceous North America, Niobrara Formation 83.5 Ma.
In the sunny waters of the shallow Western Interior Seaway, ichthyodectid fish scatter before an elasmosaur. Styxosaurus reached 12 metres in length, half of which was neck and it probably ambushed its prey using its long neck to pick off small fish.
Baculites, a form of straight shelled ammonite hang in the water column. With a variety of shell morphologies they are excellent indicator fossils and can help palaeontologists date sediments precisely.
Ink & graphite drawing
Wardie Shales Lower Lothian
Group Edinburgh Scotland Carboniferous 340Ma.
In the myriad waterways of swampy, carboniferous Scotland, small sharks, (elasmobranchs) were not the dominant aquatic predators we think of today. Rather they grew seldom larger than a meter, tiny alongside the largest freshwater fish yet discovered.
Rhizodus hibberti, featured languishing in the black mud at the bottom of the pool, was a true giant, although the Scottish specimen is a mere 2.5 meters long, it was know to reach lengths of eight meters making it possibly the largest fresh water fish that ever lived.
It would have been an ambush predator and the fifteen or so different fish species with which is shared its dark world, would have done well to remain clear of its jaws.
Wardie Shale deposits near Edinburgh are of international
significance, the black, oil-rich mudstone, containing the remnants
of an aquatic ecosystem from a time when Scotland was at the equator.
Flat and forested by strange Lycopod ‘trees’ Chordates, Calamites
and Seedferns, the landscape superficially resembled the Amazon or
Mississippi deltas today. Reptiles had only begun to evolve and the wet low
lying forests were home to giant insects and vast lagoons populated
by actinopterygian fish (foreground left) and strange spiny sharks,
Acrylic painting & coloured pencils
Clidastes Cretaceous North
America, Mooreville Chalk Formation 99-66 Ma.
Mosasaurs were the dominant marine predators of their age, diversifying into a multitude of forms to rival the plesiosaurs, pliosaurs and sharks in Late Cretaceous seas.
Many of the more derived forms such as Tylosaurus and Mosasaurus grew to immense size, their overall morphology adapted to ambush large prey in an open-ocean environment. Yet some mosasaurs, like Clidastes seldom grew longer than two or three metres and retained an overall body plan similar to their earlier aigialosaur relatives from which they evolved.
Although now long extinct, mosasaurs are related closely to living monitor lizards and belong phylogeneticaly in the superfamily Varanoidea; a group of related reptiles including the extant Komodo dragon, the largest terrestrial lizard alive today.
Indeed, it is not uncommon to see Komodo dragons and other varanid reptiles swimming, with some species such as the Nile monitor spending a considerable portion of its life in water.
Mosasaurs, however, were fully aquatic animals, having evolved to spend their entire lives in water. A fossil of a basal mosasauroid found to contain advanced embryos in its abdomen implies that early in their evolutionary history mosasaurs were able to give birth to live young.
Clidastes is a basal member of the derived mosasaurinae, lacking the deep tail fluke seen in advanced members of the clade, and although not known for certain it probably hunted cephalopods and small fish in shallow surface water.
Stippled ink drawing
Waimanu on the Rocks
Waipara Greensand, Middle Palaeocene, Chatham Islands, New Zealand. 62 Ma.
Today, penguins are confined to the southern hemisphere, except for the Galapagos penguin, just north of the equator. From their inception penguins appear to have been limited to the southern hemisphere of our planet, the majority of fossil remains coming from New Zealand, Argentina and South Africa.
The earliest recognised fossils that can be accurately attributed to the sphenisciformes, the taxonomic order of which Waimanu is a basal representative, come from the Greensand sediments from the south Island of New Zealand. Exposed by the cutting of the Waipara River, these dark sediments are marine in origin and represent the shallow seafloor as laid down some 62 million years ago. Here the first remains of Waimanu were recovered, a Neoave clearly already adapted to an aquatic lifestyle.
Waimanu is the earliest known fossil penguin species, but its ancestry is certainly much older, originating in the late cretaceous period. Its unknown cretaceous forebears may have retained the power of flight, having not yet become the fully aquatic birds we know today. If fossil remains are found, they may be hard to recognise as penguin ancestors.
At the time Waimanu evolved, the earth was generally much warmer than it is today and, unlike most extant penguins, Waimanu did not live or breed on ice.
I have depicted it here on seaweed-covered rocks. Its short legs and webbed feet are very like modern penguins, so its upright stance and walk would also have been similar. Its wings too would have been penguin-like, but less well adapted to ‘flight’ under water, the bones not yet as flattened in profile as in modern birds. Here, the similarities end, for Waimanu’s head differs considerably from modern penguins, with a longer beak, and a head profile similar to that of a Loon.
Late Jurassic North America, Morrison Formation 152-151 Ma.
Apatosaurus ajax was a giant animal. Averaging lengths of 75 feet (26 m), it was one of the real heavyweights of the Jurassic period. Unlike its more gracile contemporary, Diplodocus, Apatosaurus was more robustly proportioned and is considered by many palaeontologists to have been a generalist browser, traveling in herds between stands of riparian conifers and cycads that typified the flora of the late Jurassic landscape.
The Morrison Formation in North America is famous for producing some of the most recognisable dinosaurs, the sauropods Apatosaurus, Diplodocus, Camarasaurus and the newly reinstated Brontosaurus, the plated ornithischian Stegosaurus and the carnivores Allosaurus and Ceratosaurus.
During the bone wars of the 1870-90s the Morrison formation was a favoured prospecting ground for the famous rival palaeontologists Othniel C. Marsh and Edward Drinker Cope, who discovered and named many of these now iconic animals.
The Morrison formation outcrops in several states of the Western United States and represents deposits laid down 156-146 Ma. over a large alluvial floodplain. Stands of conifers, ferns, cycadeoid and cycad species clung to the banks on meandering rivers. The Morrison is considered to have been a hot, semi-arid savannah-like landscape visited by seasonal rains and periodic flooding.
Daspletosaurus & Centrosaurus
Late Cretaceous North America, Upper Oldman Formation 77-76Ma.
As the sun goes down on a hot Cretaceous evening 76 million years ago, two Daspleteosaurus harry a herd of Centrosaurs, singling out their prey much to the disinterest of its herbivorous brethren.
An interesting conundrum faces artists seeking to portray prehistoric life, in that less information, or less imaginative speculation, often contributes to a more realistic scientific interpretation; a silhouette requiring less involvement from the artist’s imagination than a fully rendered feathers-and-all photo-realistic montage.
Of course, we shall never know if scenarios like the one I have painted took place. But based on some predator-prey relationships that we can observe today, it is not beyond the realms of possibility.
Evidence has emerged over recent years that tyrannosaurs, and indeed many large predatory theropod dinosaurs may well have displayed pack behaviour, perhaps all or some of the time; hunting their prey as a group, with the more gracile sub-adult individuals chasing down their quarry, only for the older and heavier animals to make the kill. Although still conjecture, perhaps we are witnessing here the outcome of just such a situation; the hot Cretaceous sunset being the last for this particular ceratopsian dinosaur.
Early - Late Cretaceous North Africa. Continental Red Beds 112-97 Ma.
Spinosaurus aegypticus was a large theropod dinosaur from the Early Cretaceous of North Africa.
With its impressive dorsal sail formed from elongated vertebral spines. Spinosaurus aegypticus is arguably one of the most bizarre predatory dinosaurs. It was certainly one of the longest, up to fourteen metres. Sadly allied bombing during World War II destroyed the type specimen, and current estimates are based on more fragmentary remains. Although predominantly a pescitarian as evidenced by its crocodilian-like skull, it is unlikely it would have overlooked the chance of scavenging the remains of another dinosaur. A pair of smaller abelisaurid theropods have been attracted by the smell. Elosuchus, a neosuchian crocodyliform looks on.
Ink & graphite drawing
Late Jurassic, Shishugou Formation China 160Ma.
A low-flying pterosaur Sericipterus narrowly avoids becoming a meal for a hungry metriacanthosauroid allosaur, Sinraptor.
Sinraptor, 160 Ma. meaning Chinese Thief, was a large predatory carnosaur from China. Although its name might suggest an affinity with other 'raptors' such as the famous Velociraptor, Sinraptor lived during the Late Jurassic period 160 Ma, and is part of a family of dinosaurs called the Metriacanthosauridae within the Allosauroidea.
Allosaurs were the dominant predators in most Late Jurassic environments. With long, thin heads and steak-knife teeth, they are considered to have been pack hunters, living or collecting together to bring down the giant sauropods on which they would have likely fed.
Sericipterus, a small long tailed rhamphorynicoid pterosaur, resembled many other pterosaurs from the Jurassic period, Harpactognathus in North America, rhamphoryncus from Europe and Africa and Scaphognathus from the Solnhofen Limestone deposits of Germany.
Late Jurassic North America, Morrison Formation 154-150 Ma.
The Late Jurassic was the age of giant long-necked dinosaurs, and none is perhaps better known than the sauropod Diplodocus, a surprisingly gracile member of a family which produced many of the largest land animals that ever lived.
Diplodocus carnegii pictured here grew to lengths of twenty five metres and probably browsed on ferns, cycads and bennettitales that grew along the forest margins. It shared its world with many other classic dinosaurs including Apatosaurus, Stegosaurus, Camarasaurus and the formidable carnivore Allosaurus.
The discovery in 1990 of partial skin impressions of an undescribed diplodocid from the Morrison Formation would seem to indicate this dinosaur may have possessed a row of short keratinous spines along all or part of its tail and back.
Ink & graphite drawing
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