How dinosaurs are depicted


This video is called Dinosaur Art Gallery Part 1.

From Tetrapod Zoology blog:

The changing life appearance of dinosaurs

By Darren Naish

September 1, 2014

Anyone who knows anything about Mesozoic dinosaurs will be – or certainly should be – familiar with the fact that our view of what these animals looked like in life has changed substantially within the last several decades. The ‘dinosaur renaissance’ of the late 1960s and 70s saw the flabby-bodied, tail-dragging behemoths of earlier decades be replaced by sprightly, athletic animals with big, bulging limb muscles, erect tails, and dashing patterns and colour schemes. This ‘new look’ for dinosaurs was initiated by (sometime Tet Zoo reader) Robert Bakker and then taken forwards by Greg Paul and Mark Hallett; several other artist-writers of the 1970s and 80s also helped perpetuate ‘new look’ dinosaurs, including John McLoughlin, Peter Zallinger and Doug Henderson (arguably the greatest palaeoartist of them all).

The influence of Greg Paul in particular has been so significant that the majority of ‘modern’ dinosaur renditions – those of Jurassic Park and numerous artworks, museum installations and so on – are, effectively, ‘Greg Paul dinosaurs’. Many palaeontologists don’t like crediting Greg Paul’s influence, in part because they dislike or disagree with the arguments, proposals and contentions he has made in his many technical articles and books. I think that ‘Greg Paul the publishing scientist’ is a different entity from ‘Greg Paul the technical artist’, and that’s Greg’s influence on how we imagine and reconstruct fossil dinosaurs needs to be fairly credited (see comments in Naish 2008, Conway et al. 2012). So, ‘Revolution # 1’ as goes the portrayal of Mesozoic dinosaurs* was instigated by Bakker, Paul, Hallett and their contemporaries, with Greg Paul being of pre-eminent importance.

* Because birds are dinosaurs, it should be noted that articles like the one you’re reading now are specifically about those dinosaurs that lived during the Mesozoic Era. Early birds are included in this general subject area, meaning that ‘Mesozoic dinosaurs’ and ‘non-avialan dinosaurs’ (= non-bird dinosaurs) are not synonymous.

I should say, by the way, that all of what I’ve just said is very familiar stuff to those interested in the world of palaeoart. However, many things that are ‘common knowledge’ for certain sets of people are not necessarily familiar to interested parties at large.

Moving on… So, those of us interested in the life appearance of fossil animals grew up with svelte, muscular, sometimes fuzzy or feathery ‘Paulian’ dinosaurs. Blubbery, fat-limbed dinosaurs that somehow persisted into the artwork of the mid-1980s – produced by artists, and presumably given the ok by palaeontologists, who shall remain nameless (some of you will know who I have in mind) – looked weirdly anachronistic when published, and their existence during the 1980s and persistence beyond them has always been inexplicable. What? You mean you hadn’t seen the Paulian dinosaurs that everyone else was drawing by now? Huh. Anyway…

This video is called Dinosaur pictures and Oil Paintings by Dinosaur Corporation.

Fast forward to the early decades of the 21st century. As ridiculous as it would have seemed to the palaeontologists and palaeoartists of the 1980s and before, feathered non-bird dinosaurs are now “commonplace” (to quote one study), and integumentary fuzz has been discovered on ornithischians and numerous theropods (including big tyrannosaurs). Assorted studies have shed substantial light on dinosaur facial tissues, forelimb orientation, posture, locomotion, muscle size, and tail shape. We have learnt enough for ‘Revolution # 2’ to occur – the ‘soft dinosaur revolution’ (hat-tip to Jason Brougham for this term).

With Paulian dinosaurs as the framework or bedrock, we have entered the age whereby people are able to add a more realistic amount of musculature, skin and other integumentary structures… to make the animals less shrink-wrapped. The concept of shrink-wrapped dinosaur syndrome (SWDS) arose sometime round about 2010 and has since been widely used in discussions of dinosaur life appearance. I’m not sure who originated the term, since it was used approximately simultaneously by sauropod expert Matt Wedel and palaeoartist John Conway.

We really need to talk about palaeoart. A new, augmented edition of All Yesterdays will appear in time.

Whatever, the concept emerged among several interested parties. The ‘All Yesterdays Movement’ – which has rigorous skeletomuscular reconstructive work at its core – has emerged from a desire to portray dinosaurs (and other fossil animals) with the right amount of soft stuff (Conway et al. 2012). It’s really not, as some seem to have assumed, built on the idea that anything goes. Muscles may sometimes be more extensive and more voluminous than illustrated within the ‘Paulian’ paradigm (Hutchinson et al. 2011, Persons & Currie 2011), dinosaurs may sometimes or often have sported wattles, dewlaps, soft frills and other epidermal features, and fuzzy and feathery coatings of various species were frequently thick and extensive, not sparse.

In the rest of this article I want to say a few brief things about the life appearance of Mesozoic dinosaurs. The old, chunky, tail-dragging dinosaurs of the 1950s and before are dead, but the shrink-wrapped, sparse-feathered ones of the 1980s should be, too. Again, this idea is familiar to those who keep up to speed on dinosaur life appearance, but I get the impression that it’s not that appreciated overall.

A very brief guide to dinosaur life appearance

Articulated skeletons, trackways, and the way bones fit together show that dinosaurs generally walked and ran with horizontal bodies and tails that were approximately parallel to the ground. Tail-tips might have drooped or dangled, but tails only really sloped downwards in horned dinosaurs, and to a degree in therizinosaurs and brachiosaur-like sauropods. This doesn’t mean that all dinosaurs were all horizontal all the time. Bipedal species of many sorts likely stood with diagonal or even near-vertical bodies when scanning the landscape, testing for odours, or showing off to other animals. And quadrupedal species like certain sauropods (most notably diplodocids) and stegosaurs were also almost certainly capable of semi-erect poses too. Therizinosaurs must have walked and stood with a perpetual diagonal body posture.

Theropods – the predatory dinosaurs and birds – did not walk around with ‘bunny hands’ as used to be shown (that is, with their palms facing the ground). Rather, the arms and hands were articulated such that the palms faced inwards and the hand could not be pronated – that is, it could not be rotated to face downwards (e.g., Gishlick 2001, Senter & Robins 2005). This raises all manner of issues as goes hand function and predatory behaviour, but that’s an issue I can’t cover here. ‘Palms-inward’ hands were also present in bipedal sauropodomorphs (the plateosaurs and their kin) (Bonnan & Senter 2007).

The idea that bird-like non-avialan coelurosaurs were feathered has been popular in some circles since the late 1980s at least. That’s right, feathered (non-avialan) dinosaurs are not a new thing, but were ‘normal’ and oft-illustrated by a whole generation of people interested in the life appearance of dinosaurs. Bakker, Hallett and Paul were all illustrating feathered theropods throughout the late 1970s and 80s but it was Paul’s 1988 book Predatory Dinosaurs of the World (Paul 1988) that launched the idea into mainstream dinofandom (see also Paul 1987). Paul’s arguments were pretty sensible: they basically hinged on the fact that non-bird maniraptorans like Velociraptor are extremely similar in form and anatomical detail to indisputably feathered Archaeopteryx. While quite a few palaeontologists agreed that the notion of a feathery Velociraptor was at least plausible, what I remember from the 1980s and early 90s is those palaeontologists who declared this idea unlikely and overly speculative. Nope, it’s scales scales scales until proven otherwise, they said. Of course, it turns out that Paul and those other palaeoartists were actually right all along.

Well, actually: now that we have lots of feathered non-bird theropods, it turns out that Paul and his followers were too conservative. These animals didn’t have a thin or sparse veneer of feathers on just part of their bodies. Rather, they were thickly clothed in them just as birds are, with fuzz covering much of the face and snout, long feathers obscuring the arms and hands and much of the legs, and fan-like arrangement of large feathers sprouting from the tail. You can do your bit to help spread the news as goes properly feathered non-avialan theropods by backing Rebecca Groom’s Palaeoplushie Velociraptor project or by purchasing my new “Just say NO to unfeathered non-avialan maniraptoran theropod dinosaurs” t-shirt at the Tet Zoo Redbubble shop!

Sauropods with softer faces

Moving on to sauropods… Sauropods were mostly covered in non-overlapping scales but some had osteoderms and tubercles across the back. Diplodocids – and maybe others – had a row of triangular, laterally compressed spines running along the dorsal midline (Czerkas 1992). The hands of ‘advanced’ sauropods were columnar, semi-circular structures where the thumb claw was the only claw present (and even this was reduced and lost in the largest, most speciose sauropod clade: Titanosauria). Hindfeet were oval, backed by a giant fat-pad, and with three (sometimes two, sometimes four) laterally compressed claws on the innermost toes.

Debate continues over the neck posture of sauropods. I’m one of several researchers who thinks – based in part on data from living animals – that sauropods (and other sauropodomorphs) routinely held their necks in high, raised poses, not horizontal or downward-sloping ones (Taylor et al. 2009). Sauropods have traditionally been illustrated with sunken, skeletal faces and nostrils perched high up in the bony nostril openings. However, work on sauropod facial tissues (Witmer 2001) means that we should imagine them with ‘softer’ faces where tissues obscured much of the underlying bony anatomy, and the fleshy nostrils were located down on the muzzle and not well up and back in the bony nostril opening [adjacent illustration take from this SV-POW! article on the life appearance of sauropods]. The notion that sauropods might have had tapir- or elephant-like trunks has been suggested a few times but is not consistent with any aspect of skull anatomy, nor with the tooth wear seen in the group. It’s also contradicted by data on nerve anatomy (animals need big facial nerves to operate a trunk) (Knoll et al. 2006). I’ve written about this idea before – see the links below.

Ornithischians, fuzzy and otherwise

Finally, what about ornithischians – the third great group of dinosaurs, the one that includes stegosaurs, ankylosaurs, ornithopods, ceratopsians and pachycephalosaurs? Beak tissue definitely sheathed the anterior parts of the jaws in these dinosaurs (this is actually preserved in some hadrosaurs) but several other aspects of their facial anatomy have been controversial. The idea that skin and other soft tissue spanned the side of the mouth cavity – this is typically termed ‘cheek’ tissue even though this is very likely technically incorrect – has been popular but occasionally contested. The distribution of nutrient foramina on the jaw bones of these dinosaurs supports the idea that an extensive amount of tissue did indeed cover the sides of their jaws (Morhardt et al. 2009), and the presence of ossifications that fit in the space between the upper and lower jaws of some ankylosaurs show that a tissue web of some sort really was present.

Preserved skin impressions show that many ornithischians possessed polygonal scales over most or all of their bodies; at least some hadrosaurs also had serrated or ribbon-like frills along the back and tail. The gigantic, complex bony nostrils of hadrosaurs and ceratopsians almost certainly housed erectile or inflatable structures of some sort. Soft crests, dewlaps and other structures are suspected or known to have been present in hadrosaurs and other ornithischians, and the horns of ceratopsians, and plates and spines of stegosaurs and ankylosaurs, were certainly enlarged in size (sometimes substantially) by keratinous coverings.

The big deal about ornithischian life appearance right now concerns the presence of filamentous integumentary structures in several taxa: in the heterodontosaurid Tianyulong, the ceratopsian Psittacosaurus, and in Kulindadromeus, a bipedal ornithischian that would once have been identified as an ornithopod but is actually outside the clade that includes ornithopods and marginocephalians. Kulindadromeus is remarkable in that it is partially covered in simple filaments but also in parallel fibres that emerge from broad, plate-like structures, and in bundles of parallel, ribbon-like filaments (Godefroit et al. 2014). None of these structures are longer than 2 or 3 cm. Scales cover the feet and imbricated, rectangular scales – arranged in several longitudinal rows – are present across the dorsal surface of the tail.

The question now is how widespread such filamentous structures were across Ornithischia, and across Dinosauria in general. Were they restricted to one or two lineages, were they normal across the small-bodied members of all lineages, or were they present across diverse small-bodied and large-bodied lineages? And are the structures in ornithischians homologous with the filaments of theropods and pterosaurs? We simply need more data from more fossils before we can go further with this.

Finding information is hard – so, what to do?

Needless to say, there’s a ton more that could be said about dinosaur life appearance. What I’ve done here is merely overview, in very brief fashion, some of the more easily summarised subject areas. What do people do when they need up-to-date information on these sorts of issues? That’s not an easy question to answer. The only competent and comprehensive review of dinosaur life appearance is Paul’s 1987 book chapter (Paul 1987), and it’s now woefully out of date.

Your other recourse is to scour through the vast primary literature, or to team up with a friendly expert (and don’t go assuming that palaeontologists are necessarily useful on this sort of stuff. Those who work on phylogenetics, diversity across time, histology and so on are often not up to speed on soft tissue anatomy. Exhibit A: all those execrable and hopelessly inaccurate dinosaur images published in books that were supposedly authenticated by august working scientists). So, what’s needed? The answer: a grand new illustrated work that provides a comprehensive guide to the life appearance of fossil dinosaurs. The good news: plans to produce just such a project are underway right now. Watch this space…

For previous Tet Zoo articles on palaeoart and the life appearance of Mesozoic dinosaurs, see…

And – entirely coincidentally – today all sees the publication of my colleague Mark Witton’s article on palaeoart Patterns in Palaeontology: Palaeoart – fossil fantasies or recreating lost reality?

Refs – -

Bonnan, M. F. & Senter, P. 2007. Were the basal sauropodomorph dinosaurs Plateosaurus and Massospondylus habitual quadrupeds. Special Papers in Palaeontology 77, 139-155.

Conway, J., Kosemen, C. M., Naish, D. & Hartman, S. 2012. All Yesterdays: Unique and Speculative Views of Dinosaurs and Other Prehistoric Animals. Irregular Books.

Czerkas, S. A. 1992. Discovery of dermal spines reveals a new look for sauropod dinosaurs. Geology 20, 1068-1070.

Gishlick, A. D. 2001. The function of the manus and forelimb of Deinonychus antirrhopus and its importance for the origin of avian flight. In Gauthier, J. & Gall, L. F. (eds) New perspectives on the origin and early evolution of birds: proceedings of the international symposium in honor of John H. Ostrom. Peabody Museum of Natural History, Yale University (New Haven), pp. 301-318.

Godefroit, P., Sinitsa, S. M.,  Dhouailly, D., Bolotsky, Y. L., Sizov, A. V., McNamara, M. E., Benton, M. J. & Spagna, P. 2014. A Jurassic ornithischian dinosaur from Siberia with both feathers and scales. Science 345, 451-455

Hutchinson, J. R., Bates, K. T., Molnar, J., Allen, V. & Makovicky, P. J. 2011. A computational analysis of limb and body dimensions in Tyrannosaurus rex with implications for locomotion, ontogeny, and growth. PLoS ONE 6(10): e26037. doi:10.1371/journal.pone.0026037

Knoll, F., Galton, P. M. & López-Antoñanzas, R. 2006. Paleoneurological evidence against a proboscis in the sauropod dinosaur Diplodocus. Geobios 39, 215-221.

Morhardt, A. C., Bonnan M. F. & Keillor, T. 2009. Dinosaur smiles: correlating premaxilla, maxilla, and dentary foramina counts with extra-oral structures in amniotes and its implications for dinosaurs. Journal of Vertebrate Paleontology 29 (supplement to 3), 152A.

Naish, D. 2008. The Great Dinosaur Discoveries. University of California Press, Berkeley.

Naish, D. 2014. Rediscovering the dinosaurs. Science Uncovered 7 (June 2014), 68-72.

Paul, G. S. 1987. The science and art of restoring the life appearance of dinosaurs and their relatives – a rigorous how-to guide. In Czerkas, S. J. & Olson, E. C. (eds) Dinosaurs Past and Present Vol. II. Natural History Museum of Los Angeles County/University of Washington Press (Seattle and London), pp. 4-49.

1988. Predatory Dinosaurs of the World. Simon & Schuster, New York.

Persons, W. S. & Currie, P. J. 2011. The tail of Tyrannosaurus: reassessing the size and locomotive importance of the M. caudofemoralis in non-avian theropods. The Anatomical Record 294, 119-131.

Senter, P. & Robins, J. H. 2005. Range of motion in the forelimb of the theropod dinosaur Acrocanthosaurus atokensis, and implications for predatory behaviour. Journal of Zoology 266, 307-318.

Taylor, M. P., Wedel, M. J. & Naish, D. 2009. Head and neck posture in sauropod dinosaurs inferred from extant animals. Acta Palaeontologica Polonica 54, 213-220.

Witmer, L. M. 2001. Nostril position in dinosaurs and other vertebrates and its significance for nasal function. Science 293, 850-853.

Darren NaishAbout the Author: Darren Naish is a science writer, technical editor and palaeozoologist (affiliated with the University of Southampton, UK). He mostly works on Cretaceous dinosaurs and pterosaurs but has an avid interest in all things tetrapod. His publications can be downloaded at darrennaish.wordpress.com. He has been blogging at Tetrapod Zoology since 2006. Check out the Tet Zoo podcast at tetzoo.com! Follow on Twitter @TetZoo.

Utah dinosaur tracks site open to the public


This video from the USA is called Dinosaur Footprints Set For Public Display In Utah.

From Associated Press:

Site of dinosaur tracks to be unveiled

by Brady Mccombs

SALT LAKE CITY, UTAH – A dry wash full of 112-million-year-old dinosaur tracks that include an ankylosaurus, dromaeosaurus and a menacing ancestor of the Tyrannosaurus rex, is set to open to the public this fall in Utah.

There are more than 200 tracks near the city of Moab from 10 different ancient animals that lived during the early Cretaceous period, said Utah Bureau of Land Management paleontologist ReBecca Hunt-Foster.

They were first discovered in 2009 by a resident. Since then, paleontologists led by a team at the University of Colorado at Denver have studied them and prepared them to go on display for the general public.

The tracks include a set of 17 consecutive footprints left by [a] Tyrannosaurus rex ancestor and the imprint of an ancient crocodile pushing off into the water.

The site is one of the largest areas of dinosaur tracks from the early Cretaceous period known to exist in North America, she said.

“We don’t usually get this,” said Hunt-Foster, a paleontologist for 16 years. “It is a beautiful track site, one of the best ones I’ve ever seen.”

There are footprints from duckbilled dinosaurs, prehistoric birds, long-necked plant eaters and a dromaeosaur similar to a velociraptor or Utahraptor that had long, sharp claws.

In one rock formation, a footprint left behind by a large plant eater is right in the middle of prints from a meat-eating theropod, Hunt-Foster said.

The imprint of an ancient crocodile shows the chest, body, tail and one foot. Paleontologists believe it was made while the crocodile was pushing off a muddy bank into water.

Paleontologists believe the tracks were made over several days in what was a shallow lake. They likely became covered by sediment that filled them up quickly enough to preserve them but gently enough not to scour them out, Hunt-Foster said. Over time, as more sediment built up, they became rock. They’re near a fault line, where the land has moved up and down over the years, she said. Rain slowly eroded away layers of the rock, exposing the footprints.

Welsh Jurassic mammals feeding, new study


This video says about itself:

There Are No Transitional Fossils?

19 April 2011

Long-sought fossil mammal with transitional middle ear found in China.

Palaeontologists have announced the discovery of Liaoconodon hui, a complete fossil mammal from the Mesozoic found in China that includes the long-sought transitional middle ear.

The specimen was found by palaeontologists from the American Museum of Natural History and the Chinese Academy of Sciences.

It shows the bones associated with hearing in mammals, the malleus, incus, and ectotympanic, decoupled from the lower jaw, as had been predicted, but were held in place by an ossified cartilage that rested in a groove on the lower jaw.

People have been looking for this specimen for over 150 years since noticing a puzzling groove on the lower jaw of some early mammals,” Jin Meng, curator in the Division of Palaeontology at the Museum and first author of the paper, said.

“Now we have cartilage with ear bones attached, the first clear paleontological evidence showing relationships between the lower jaw and middle ear,” Meng revealed

The transition from reptiles to mammals has long been an open question, although studies of developing embryos have linked reptilian bones of the lower jaw joint to mammalian middle ear bones.

The new fossil, Liaoconodon hui, fills the gap in knowledge between the basal, early mammaliaforms like Morganucodon, where the middle ear bones are part of the mandible and the definitive middle ear of living and fossil mammals.

Liaoconodon hui is a medium-sized mammal for the Mesozioc (35.7 cm long from nose to tip of tail, or about 14 inches) and dates from 125 to 122 million years.

It is named in part for the bountiful fossil beds in Liaoning, China, where it was found.

The species name, hui, honours palaeontologist Yaoming Hu who graduated from the American Museum of Natural History-supported doctoral program and recently passed away.

The fossil is particularly complete, and its skull was prepared from both dorsal and ventral sides, allowing Meng and colleagues to see that the incus and malleus have detached from the lower jaw to form part of the middle ear.

These bones remain linked to the jaw by the ossified Meckels cartilage that rests in the groove on the lower jaw. The team hypothesizes that in this early mammal, the eardrum was stabilized with the ossified cartilage as a supporting structure.

“Before we did not know the detailed morphology of how the bones of the middle ear detached, or the purpose of the ossified cartilage,” Meng said.

“Liaoconodon hui changes previous interpretations because we now know the detailed morphology of the transitional mammal and can propose that the ossified cartilage is a stabilizer.

“I”ve always dreamed of a fossil with a good ear ossicle. Now, we have had this once in a lifetime discovery,” Meng added.

From the University of Southampton in England:

Jurassic mammals were picky eaters, new study finds

August 20, 2014

Summary:

New analyses of tiny fossil mammals from Glamorgan, South Wales are shedding light on the function and diets of our earliest ancestors, a team reports. Mammals and their immediate ancestors from the Jurassic period (201-145 million years ago) developed new characteristics – such as better hearing and teeth capable of precise chewing.

New analyses of tiny fossil mammals from Glamorgan, South Wales are shedding light on the function and diets of our earliest ancestors, a team including researchers from the University of Southampton report today in the journal Nature. Mammals and their immediate ancestors from the Jurassic period (201-145 million years ago) developed new characteristics — such as better hearing and teeth capable of precise chewing.

By analysing jaw mechanics and fossil teeth, the team were able to determine that two of the earliest shrew-sized mammals, Morganucodon and Kuehneotherium, were not generalised insectivores but had already evolved specialised diets, feeding on distinct types of insects.

Lead author, Dr Pamela Gill of the University of Bristol, said: “None of the fossils of the earliest mammals have the sort of exceptional preservation that includes stomach contents to infer diet, so instead we used a range of new techniques which we applied to our fossil finds of broken jaws and isolated teeth. Our results confirm that the diversification of mammalian species at the time was linked with differences in diet and ecology.”

The team used synchrotron X-rays and CT scanning to reveal in unprecedented detail the internal anatomy of these tiny jaws, which are only 2cm in length. As the jaws are in many pieces, the scans were ‘stitched together’ to make a complete digital reconstruction. Finite element modelling, the same technique used to design hip joints and bridges, was used to perform a computational analysis of the strength of the jaws. This showed that Kuehneotherium and Morganucodon had very different abilities for catching and chewing prey.

Study co-author, Dr Neil Gostling from the University of Southampton, said: “The improvement in CT scanning, both in the instrumentation, at Light Source at the Paul Scherrer Institute in Switzerland where we scanned or even the µ-VIS Centre at Southampton, along with access for research of this kind, allows us to make inroads into understanding the biology and the ecology of animals long dead. The questions asked of the technology do not produce ‘speculation’, rather the results show a clearly defined answer based on direct comparison to living mammals. This would not be possible without the computational techniques we have used here.”

Using an analysis previously carried out on the teeth of present-day, insect-eating bats, the researchers found that the teeth of Morganucodon and Kuehneotherium had very different patterns of microscopic pits and scratches, known as ‘microwear’. This indicated they were eating different things with Morganucodon favouring harder, crunchier food items such as beetles while Kuehneotherium selected softer foods such as scorpion flies which were common at the time.

Team leader, Professor Emily Rayfield from the University of Bristol, added: “This study is important as it shows for the first time that the features that make us unique as mammals, such as having only one set of replacement teeth and a specialised jaw joint and hearing apparatus, were associated with the very earliest mammals beginning to specialise their teeth and jaws to eat different things.”

Hallucigenia, strange Cambrian fossil animal, new study


This video from the USA is called Hallucigenia at the Chicago Field Museum.

From daily The Independent in Britain:

Hallucigenia revealed: The most surreal creature from strangest period in history of life on Earth

Scientists solve mystery of a creature from the Cambrian lagoons

Steve Connor, science editor

Saturday 16 August 2014

If Salvadore Dali were God, he would surely have designed an animal that looked like Hallucigenia. It has been described as the most surreal creature that lived in the strangest period in the history of life on Earth, more than 500 million years ago.

After more than four decades of studying fossilised imprints, scientists believe they have finally nailed Hallucigenia’s position in the tree of life, and in the process discovered its only living descendants.

Hallucigenia, named because of its dream-like, trip-inducing appearance, is one of the many marine animals that rather abruptly appear in the fossil record during a period in pre-history known as the Cambrian explosion, a biological bang that detonated the evolution of complex life-forms about 542 million years ago.

Until the Cambrian explosion, life had been bumbling along for about three billion years, with evolution producing nothing much more animate than a bath sponge. After the explosion, creatures with complex body plans evolved that walked, crawled, swam and burrowed – and Hallucigenia was one of them.

Scientists were so thrown by Hallucigenia when its small fossils were first analysed 40 years ago that they thought its front end was its back end, and its top was its bottom. They even thought it was an evolutionary one-off that had left no descendants alive today.

However, scientists now believe they have finally been able to locate Hallucigenia’s position in evolutionary history by showing that it is the ancestor of a small group of worm-like creatures with short, stubby legs that can be found today, living unobtrusively in the undergrowth of tropical forests.

Martin Smith and Javier Ortega-Hernandez of Cambridge University have detected key physical similarities between Hallucigenia and the so-called velvet worms, known more formally as the onychophorans – the first time zoologists have been able to rule conclusively on the creature’s true role in history.

Their study, to be published in the journal Nature, is based on a detailed analysis of high-magnification images of the fossils of Hallucigenia, which grew no bigger than about 3.5cm long, showing five key characteristics that link the species to the velvet worms.

Among the most important features is the way the claws at the end of its limbs are arranged. Under an electron microscope, each claw has two or three successive layers of cuticle nestled one within the other, like the layered skins of an onion.

Dr Smith said: “We think this enabled them to grow a new set of claws before they shed their skins, which they had to do to grow. A very similar feature is found in the claws and jaws of the velvet worms, and no other animal shares this particular characteristic.

“It means that the animals do not have to wait for a new claw to form after shedding their skin to grow – they already have one ready formed,” he explained.

Zoologists have also not always been completely sure which end of Hallucigenia is the front and which is the back, although Dr Smith said his research clears this up – the front has two or three pairs of appendages and the back has a rounded end where its body-length gut probably terminates.

It is now clear that the fearsome spikes on Hallucigenia’s back, which were once confused for stilt-like legs, are almost certainly a defensive mechanism against the increasing number of predators that emerged during the Cambrian explosion.

Fossils: Burgess Shale

The Cambrian explosion is named after the geological period that began about 541 million years ago, when a remarkable variety of marine animals first appear in the fossil record.

Most fossils are formed from the hard parts of living organism, such as bones or shells. However, details of the soft body parts of Cambrian creatures can be seen in a rock formation known as the Burgess Shale in the Canadian Rocky Mountains.

Hallucigenia was just one of many bizarre animals to live at this time. Other creatures included a fearsome predator called Anomalocaris, armed with two vicious-looking jaws and large eyes, and Wiwaxia, which looked like a Viking helmet with spikes.

For evolutionists, this period is one of the most interesting in the 3.5-billion-year history of life on earth because this was when many of the complex body plans seen in today’s animals are first detectable, even though they must have evolved from something earlier in history.

“It’s often thought that modern animal groups arose fully formed during the Cambrian explosion. But evolution is a gradual process,” said Martin Smith of Cambridge.

“Today’s complex anatomies emerged step by step, one feature at a time. By deciphering ‘in-between’ fossils like Hallucigenia, we can determine how different animal groups built up their modern body plans,” he said.

Burgess Shale Fossil Specimens: here.

‘Butterfly-headed’ pterosaurs discovery in Brazil


A new species of flying reptile from the Cretaceous Era, Caiuajara dobruskiii, has been unearthed in southern Brazil. The creature, described in a 2014 PLOS ONE paper, sported a bony crest on its head. Credit: Maurilio Oliveira/Museu Nacional-UFRJ

From Live Science:

Flock of Ancient ‘Butterfly-Headed’ Flying Reptiles Discovered

By Tia Ghose, Staff Writer

August 13, 2014 02:00pm ET

An ancient flying reptile with a bizarre, butterflylike head has been unearthed in Brazil.

The newfound reptile species, Caiuajara dobruskii, lived about 80 million years ago in an ancient desert oasis. The beast sported a strange bony crest on its head that looked like the wings of a butterfly, and had the wingspan needed to take flight at a very young age.

Hundreds of fossils from the reptile were unearthed in a single bone bed, providing the strongest evidence yet that the flying reptiles were social animals, said study co-author Alexander Kellner, a paleontologist at the Museu Nacional/Universidade Federal do Rio de Janeiro in Brazil. [See Images of the Bizarre 'Butterfly Head' Reptile]

Rare find

Though pterosaur fossils have been unearthed in northern Brazil, no one knew of pterosaurs fossils in the southern part of the country. In the 1970s, a farmer named Dobruski and his son discovered a massive Cretaceous Period bone bed in Cruzeiro do Oeste in southern Brazil, a region not known for any fossils, Kellner said. The find was forgotten for decades, and then rediscovered just two years ago. The team dubbed the reptile Caiuajara dobruskii, after the geologic formation, called the Caiuá Group, where it was found, as well as the farmer who discovered the species, Kellner said.

C. dobruskii belonged to a group of winged reptiles known as pterosaurs, which are more commonly known as pterodactyls.

Hundreds of bone fragments from the species were crammed in an area of just 215 square feet (20 square meters). At least 47 individuals — and possibly hundreds more — were buried at the site. All but a few were juveniles, though the researchers found everything from youngsters with wingspans of just 2.1 feet (0.65 m) long to adults with wingspans reaching 7.71 feet (2.35 m). The fossils weren’t crushed, so the 3D structure of the animals was preserved, the authors wrote in a research article published today (Aug. 13) in the journal PLOS ONE.

The ancient reptiles’ bony crests changed in size and orientation as the pterosaurs grew.

Because the adult skeletal size (other than the head) wasn’t much different from the juveniles’, the researchers hypothesized that C. dobruskii was fairly precocious and could fly at a young age, Kellner said.

Water congregation

Based on the sediments in which the bones were found, the area was once a vast desert with a central oasis nestled between the sand dunes, the authors wrote in the paper.

Ancient C. dobruskii colonies may have lived around the lake for long periods of time and died during periods of drought or during storms. As the creatures died, the occasional desert storm would wash their remains into the lake, where the watery burial preserved them indefinitely, the researchers said. Another possibility is that the pterosaurs stopped at this spot during ancient migrations, though the authors suspect that is less likely.

The bone bed, with its hundreds of individuals in well-dated geological layers, is some of the strongest evidence yet that the fruit-eating animals were social, Kellner said.

“This was a flock of pterosaurs,” Kellner told Live Science.

This finding, in turn, strengthens evidence that other pterosaur species may have been social as well, the authors wrote in the paper.

New dinosaur discovery in Venezuela


This video is called New type of dinosaur Laquintasaura venezuelae was turkey-sized.

From Wildlife Extra:

A new species of dinosaur that roamed northern South America 200 million years ago has been discovered in Venezuela.

This is the first time a dinosaur has been has been found here and in this honour it has been named Laquintasaura venezuelae.

Measuring about a metre long and 25 centimetres tall Laquintasaura would have been about the size of a small dog and belong to the ‘bird-hipped’, or Ornithischia, group of dinosaurs which later gave rise to Stegosaurus.

It was largely herbivorous- though the curve of some of its teeth suggest it might have also feasted on insects and small prey.

The discovery of it in small groups, which included juveniles and fully grown adults, could indicate they were living in herds; something that was not thought to have occurred in this sort of dinosaur until the Late Jurassic around 40 million years later.

‘It is fascinating and unexpected to see they lived in herds, something we have little evidence of so far in dinosaurs from this time,’ says lead author Dr Paul Barrett. “It’s always exciting to discover a new dinosaur species but there are many surprising firsts with Laquintasaura.”

See also here.

The scientific description of this new species is here.

Dinosaurs got extinct, how about dinosaur age plants?


This video says about itself:

The Day The Mesozoic Died HD

30 May 2013

The disappearance of the dinosaurs at the end of the Cretaceous period posed one of the greatest, long-standing scientific mysteries. This three-act film tells the story of the extraordinary detective work that solved it. Shot on location in Italy, Spain, Texas, Colorado, and North Dakota, the film traces the uncovering of key clues that led to the stunning discovery that an asteroid struck the Earth 66 million years ago, triggering a mass extinction of animals, plants, and even microorganisms. Each act illustrates the nature and power of the scientific method. Representing a rare instance in which many different disciplines—geology, physics, biology, chemistry, paleontology—contributed to a revolutionary theory, the film is intended for students in all science classes.

From Laelaps blog today:

Planting the Cenozoic Garden

by Brian Switek

Sixty six million years ago, a global catastrophe extinguished the non-avian dinosaurs. This is common knowledge. It’s also too narrow a view. Various forms of life disappeared in the same geologic instant – from coil-shelled ammonites to some forms of mammal – and others, for reasons as yet unknown, survived.

Plants are among the neglected of the victims and survivors. A magnolia tree does not hold the same cultural cachet as Tyrannosaurus. The post-impact “fern spike” is often cited as a symbol of wide-ranging devastation, but, outside technical journals, that’s about the extent of our attention span for paleoflora. That’s a shame. If we’re going to understand how life on Earth was so deeply wounded 66 million years ago, and how it bounced back, we should be looking more closely at the prehistoric garden.

Hot on the heels of a review summarizing the global dinosaurian picture at the end of the Cretaceous, Lund University paleobotanists Vivi Vajda and Antoine Bercovici have now assembled a view of how plants were affected by the Earth’s fifth mass extinction. Prehistoric pollen and spores tell the story.

The advantage of looking at fossil pollen, Vajda and Bercovici write, is that there’s plenty of it. That’s not only because plants produce large amounts of the reproductive material, but because pollen is also incredibly durable. If you want to see who’s living where, and how environments change through time, these microscopic plant fossils are good way to do it.

In some ways, the story of the Cretaceous plants echoes what paleontologists have found among other forms of life. The Cretaceous world was a highly-dynamic one marked by fluctuating sea levels, the further breakup of continents, and the formation of new mountain ranges. All this moving and shuffling created evolutionary pockets where new species could evolve in relative isolation, becoming restricted to their particular province. Plants proliferated and evolved according to these boundaries just as dinosaurs did.

Each of the pollen provinces, outlined by Vajda and Bercovici, have their own distinctive profile. In northern North America, Asia, and a few spots in South America, Late Cretaceous sediments commonly contain Aquilapollenites – pollen thought to have come from a group of plants closely related to the modern sandalwood. A neighboring province – stretching from eastern North America to the Himalayas – is dominated by pollen from a Cretaceous birch relative, while rocks from the same time in northern South America, central Africa, and India are rife with pollen from palms. Rounding out the set, a southern hemisphere swath has plenty of pollen from plants related to southern beeches and shrubs.

These were not the only plants to exist in those areas, of course, but their pollen broadly delineates differentiated patches. Paleobotanists can zoom in from there, and, as with dinosaurs, the best-studied sites on the planet document the end of the Cretaceous through the beginning of the Paleogene in western North America.

The forests that Tyrannosaurus and Triceratops knew were dominated by angiosperms – flowering plants – with some conifers, ferns, ginkgos, and cycads for good measure. Palm trees stood alongside evergreens and towered above a shrubby understory in these Late Cretaceous forests. In the aftermath of the impact 66 million years ago, however, those forests were replaced by a relatively small collection of angiosperms, a shadow of the diversity that the Edmontosaurus and kin knew.

Plants suffered extinctions just as many other forms of life did. In fact, some of them dwindle to nothing right at the K-Pg boundary are called “K-species” or “K-taxa.” In the pollen record of North America, for example, the sandalwood relative and a suite of species in seven other genera give way to species in just two genera. Overall, about 60% of plant species present in Cretaceous North America went extinct. The rest of the globe reflects a similar pattern, albeit with different species. Many pollen-producing plants either went entirely extinct or became much less abundant.

Clues from the earliest days of the Paleogene track how plant life eventually bounced back. While sites in New Zealand preserve a “fungal spike” from when mushrooms and their ilk thrived on decomposing matter under blacked-out skies, the subsequent “fern spike” records when pioneering plants – primarily ferns – quickly spread as sunlight began to return. The angiosperms, as well as some conifers, followed, but with fewer species than before. Depending on the location, plant life took between one and ten million years to recover to pre-extinction levels of diversity.

As with the animals, though, why some plants went extinct and others persisted is a mystery. Perhaps some were simply lucky enough to grow in places that were less affected by the devastation following the asteroid strike. Then again, Vajda and Bercovici point out, some researchers have suggested that plants carrying additional sets of chromosomes – or were polyploid – might have had the genetic flexibility to more quickly adapt after ecological shock.

Discerning what made a survivor isn’t just an exercise in replaying ancient history, though.

Vajda and Bercovici argue that two previous mass extinctions – roughly 251 and 200 million years ago – follow a similar pattern of a highly-diverse flora being pruned back, followed by crisis species, pioneer communities, and ecosystem recovery in sequence. Which left me to wonder if we’re going to see this pattern again. If  we’re not yet in a Sixth Extinction, we’re close, and identifying likely survivors verses vulnerable species is an essential part of conservation triage. By sifting through the past, down to the tiniest pollen grain, we can reflect on what sort of future we want to create.

Reference:

Vajda, V., Bercovici, A. 2014. The global vegetation pattern across the Cretaceous-Paleogene mass extinction interval: A template for other extinction events. Global and Planetary Change. doi: 10.1016/j.gloplacha.2014.07.014