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A dinosaur outside an AZ rock shop. Photo courtesy David Williams.

This week’s Dinosaur Sighting comes to us from David Williams, who snapped a shot of a cowgirl riding a rather threadbare dinosaur outside Stewart’s Rock Shop in Arizona.

Fortunately for her the dinosaur appears to be some sort of narrow-footed sauropod so she doesn’t have to worry about being eaten, but given how high a dinosaur like Apatosaurus could lift you off the ground I would still be a little wary of riding a long-necked dinosaur.

Have you stumbled across a dinosaur where you did not expect one? If you have, and have a photo of the encounter, send it to us via dinosaursightings@gmail.com and you might see it here!

An early restoration of Hadrosaurus mounted in 1868. From Wikipedia.

November 24, 2009 will mark the 150th anniversary of the publication of Charles Darwin’s On the Origin of Species, and scientists have already started the celebrations. Last week, for example, the University of Chicago hosted a series of talks by some of the top evolutionary scientists working today. Among those delivering lectures was paleontologist Paul Sereno.

According to notes posted by blogger PZ Myers, early on in the discussion Sereno puzzled over why Darwin neglected many fossils, and dinosaurs in particular, in his most famous book. Dinosaurs are very closely related to evolutionary science today, but Darwin appeared to ignore them. Why?

Sereno posited that Darwin’s tense relationship with the Victorian anatomist Richard Owen, who coined the term “dinosaur” in 1842, kept him from talking about dinosaurs. Owen was a brilliant scientist but his cantankerous attitude was well-known. Worse than that, even though Owen was an evolutionist he disagreed strongly with Darwin over what the mechanism of evolution was, and his criticism of Darwin has fooled many people into thinking that Owen was a young-earth creationist.

The problem is that there is virtually no evidence to show that Darwin ignored dinosaurs because he was afraid of big, bad Richard Owen. In all of Darwin’s correspondence with other scientists there is almost no mention of dinosaurs at all, and when Darwin later addressed dinosaurs he did so to show how little was known about the fossil record.

As I wrote earlier this year, during Darwin’s time dinosaurs were enigmatic creatures. Not only were they very different from living reptiles, they were very different from each other, and most of the first specimens that were discovered were extremely fragmentary. It was not until 1858, the year before On the Origin of Species was published, that the relatively complete skeleton of Hadrosaurus was found in New Jersey.  This discovery, along with several others, made scientists start to reconsider what dinosaurs looked like right as Darwin’s book was being published.

I think Darwin was wise to leave dinosaurs out of On the Origin of Species. At the time of his writing, only a few genera were known from incomplete specimens, and no one would be able to tell what they had evolved from or if they left any living descendants. The seemingly aberrant forms of the dinosaurs hinted that there was more yet to be found in the fossil record, but they could not yet be pressed into the service of holding up the evolutionary mechanism Darwin was proposing.

Yet this, too, is a hypothesis. Darwin is long dead, and we cannot ask him why dinosaurs did not figure into his work. Still, I think the view presented here more closely represents Darwin’s concerns that what Sereno has proposed.

A restoration of Jane (right) being bitten on the face by a tyrannosaur of about the same size. From the Palaios paper.

Humans youngsters often use their hands and arms to push and shove, but young Tyrannosaurus were obviously a bit different than us. It would take a lot of effort for two of the fighting dinosaurs to get close enough to scrabble at each other with their small arms, and so they employed a different tactic instead: they bit each other on the face. As reported in the journal Palaios, the controversial tyrannosaur skeleton known as “Jane” shows signs of just such an encounter.

For years scientists have debated whether Jane is a juvenile Tyrannosaurus or representative of a hypothetical smaller tyrannosaur genus, Nanotyrannus, but it is not the purpose of the present paper to resolve this issue. Instead paleontologists Joseph Peterson, Michael Henderson, Reed Scherer and Christopher Vittore document the presence of several puncture wounds in the bone around Jane’s snout that could only have been made by another young tyrannosaur. Like living crocodiles and alligators, tyrannosaurs may have bitten each other on the face during confrontations to establish social dominance, and the pattern of damage on Jane’s snout is more consistent with this kind of social interaction than with an attack with an intent to kill her or feed upon her. It was pretty harsh, but face-biting was a way for theropod dinosaurs to keep individuals in line.

Based upon the details of the punctures the two tyrannosaurs appear to have been facing each other when Jane was bitten. Unlike the fragment of Gorgosaurus jaw discussed here last month, Jane’s wounds show signs of healing, and unlike the Tyrannosaurus study suggesting that dinosaurs suffered from a bird disease, there is no indication of infection. She survived the attack and healed.

This does not mean that Jane was totally unaffected by the bite. Bone is a living tissue that is constantly being remodeled as an organism grows, and damage to bones at a young age can affect the way bones grow. As such the punctures in Jane’s skull caused her snout to bend a little to the left during growth. This would not have affected her ability to hunt or bite, but it would have given her a slightly asymmetrical appearance.

"A Visit to the Antediluvian Reptiles at Sydenham - Master Tom strongly objects to having his mind improved." From Four Hundred Humorous Illustrations by John Leech.

When I was about six years old, a traveling exhibit of animatronic dinosaurs came to a nearby town. I knew that dinosaurs were extinct—my parents had taken me to see what was left of them at the American Museum of Natural History in New York—but the metal-and-plastic robots were the closest I would get to seeing a living dinosaur. I couldn’t wait to go meet them in person.

I got my chance one weekend morning, and I was terrified. Even though the dinosaurs were all miniaturized to fit in the cramped exhibit space they were all still much bigger than I was. Sharp horns glinted in the low lighting and the Tyrannosaurus wore a wicked smile that said “I eat things like you for breakfast.” I took refuge around the corner, watching the roaring and snorting beasts from a place of safety until my parents convinced me that it was safe.

I loved dinosaurs, and still do, but to see them come “back to life” was intensely frightening. The exhibit was meant to be educational but it is awfully hard to ignore a towering monster who seems to be eying you for its next meal. The Victorian cartoonist John Leech recognized this well. In 1855 Leech created a cartoon for the humor magazine Punch of a young boy being led through the sculpted menagerie of dinosaurs (as they were originally envisioned by the anatomist Richard Owen) at the Crystal Palace Park. The caption reads, “A visit to the antediluvian reptiles at Sydenham – Master Tommy strongly objects to having his mind improved.” The original cartoon was just sold at auction.

There was some political context to Leech’s cartoon, primarily about the “intellectual improvement” of the middle class as embodied by Master Tom, but the more literal interpretation still rings true. Cultivating an understanding dinosaurs and their world is a great way to teach science, but coming face to face with the creatures can be quite scary. Even skeletons, denuded of animating flesh and blood, can cause people to quicken their steps when the lights go out in the museums at closing time. No matter how much we learn about dinosaurs as the animals they truly were, they will always be monsters that are only separated from us by time.

Dinosaurs and humans are shown living together in the Creation Museum in Kentucky. From Flickr user yumiec00kies.

Earlier this year Texas updated the name of its official state dinosaur, a sauropod dinosaur previously called Pleurocoelus but recently renamed Paluxysaurus. To celebrate the name change, a team of scientists is creating a full restoration of the dinosaur’s skeleton for the Fort Worth Museum of Science and History, but not everyone was happy about the announcement of this plan in the Star-Telegram newspaper.

In a letter to the editor, Richard Hollerman of Richland Hills, Texas, took offense that the newspaper did not pay heed to his personal beliefs, namely that humans and dinosaurs lived at the same time less than 10,000 years ago. There is no evidence to support this claim, but Mr. Hollerman chastised the paper for “blindly accepting unfounded assertions by unbelieving paleontologists.”

This triggered an overwhelming response from Hollerman’s neighbors in the state. The paper printed at least seven replies that picked apart Hollerman’s anti-science tirade. Said Mark Stevens from Forth Worth:

According to creationists, science is correct about the following:

Chemistry, computer science, mathematics, engineering, sociology, systems science, psychology, medicine, nuclear science, agronomy, astronomy, nanotechnology, acoustics, biophysics, condensed matter physics, electronics, fluid dynamics, geophysics, plasma physics, vehicle dynamics, solar astronomy, meteorology, limnology, soil science, toxicology, marine biology, parasitology, anatomy, biochemistry, structural biology, entomology, cetology, phylogeny, algebra, calculus, cartography, geopolitics, criminology, agriculture, language engineering, pathology, pediatrics, nutrition, physical therapy and dermatology.

But for some reason, according to creationists, science is wrong about evolution. How is that even possible?

Another commenter, Charlie Rodriguez from the city of Arlington, replied that Hollerman’s assertions would be a joke if not for the many others who believe the Bible should be read as a science book. There has been a proliferation of “creation museums” over the past several years, and “evolution” is still a dirty word in some places in the country. Even so, it was heartening to see so many people stand up for paleontology, evolution, and good science.

[Hat-tip to Millard Fillmore's Bathtub for bringing this story to our attention.]

Not quite the Dinosaur Capital of the World

When Brian Switek polled readers about the Dinosaur Capital of the World, he included “Bedrock” as a gag answer. It did pretty well—beating out “Other” but losing, as did Liaoning and Glen Rose, to Drumheller. An astute reader pointed out that there is a way to visit Bedrock aside from being a cartoon character—it’s a campground just south of the Grand Canyon.

It was sort of surreal to go from one of the most spectacular geologic sites in the world (where I saw fossil sponges and Paleozoic trackways last week) to a kitschy roadside attraction. The cartoon-land colors are faded in the desert sun, and Fred’s wooden-wheeled car looks a bit lopsided. But sure enough, there is a dinosaur statue in the parking lot. And some sort of yellow pterosaur behind the wall, perched on a volcano.

Have you seen a dinosaur in an unusual place? Snap a photo and send it to dinosaursightings@gmail.com and you may see it here!

Croutons Not Recommended: Paleochick points us to this blast from the past: Julia Child turns her kitchen into a biolab and cooks up a batch of primordial soup. (The video played in the Smithsonian National Air & Space Museum’s now-closed “Life in the Universe” gallery.)

Worst. Article. Ever. The recent discovery of Darwinopeterus has “ensured that everyone has jumped on the pterosaurs-are-cool bandwagon,” writes David Hone over at Archosaur Musings. The predictable result—lots of inaccurate, sensationalist media coverage. David points us to one newspaper article that he feels may take the prize for “getting as much wrong as it is possible to in the least words while massively misrepresenting the science and introducing a ton of irrelevant nonsense that the researchers never commented on or mentioned at any point in order to try and ramp up the interest levels.”

Why You Should Always Clean Your Pool: Paleoblog scrutinizes a new theory explaining the mass extinction of the dinosaurs: toxin-producing algae.

Speaking of Mass Extinctions: Paleontologist Sankar Chatterjee of Texas Tech University thinks that a giant basin in India, called Shiva, could be the impact crater of the meteor that is believed to have killed off the dinosaurs. Bob’s Dinosaur Blog reports that the theory got a “mixed reception” at the latest meeting of the Geological Society of America.

Whose Life is it Anyway? Catalogue of Organisms presents another “Taxonomy Trivia Quiz,” which challenges readers to guess the identity of 15 organisms “previously placed in quite different taxonomic positions from the ones they occupy now.” Answers are posted here. (No cheating!)

Art in Real Time: Canadian artist Peter Bond treats us to another “live blogging” art session, as he sketches an allosaur-barosaur smackdown.

What a Ness: At Tetrapod Zoology, Darren Naish compiles a list of his favorite sightings of the Loch Ness monster—on land.

Update: As I noted in my previous Blog Carnival, the Tyrannosaurus rex skeleton “Samson” went up for auction in Las Vegas. Despite my fears that it would end up in Kid Rock’s basement, nobody purchased it. According to TheStreet.com, “The lack of qualified buyers for Samson was blamed on the fact that the skeleton was put on the market rather hastily by its seller, leaving many interested parties unable to pull together financing.”

Maybe paleontologists could “rescue” Samson by holding a telethon. Any volunteers?

A pair of pachycephalosaurs face off. Photographed at the Museum of Ancient Life at Thanksgiving Point, Utah.

If you knew nothing at all about dogs, but you were presented with a lineup of the skeletons of a variety of breeds from chihuahua to bulldog to German shepherd to mastiff, you could be excused for thinking they were different species. Their skeletons seem to be so different, yet we know they are all just varieties of one subspecies, Canis lupus familiaris, that have been created through artificial selection. Paleontologists, on the other hand, do not have breeder’s records and must think carefully about what distinguishes one species of dinosaur from another. A new study by Jack Horner and Mark Goodwin in the journal PLoS One suggests that some dinosaurs previously thought to be separate species, even genera, were really just the growth stages of one species of dinosaur.

The dinosaurs that are the focus of the new study are three “bone-heads,” or pachycephalosaurs: Pachycephalosaurus, Stygimoloch, and Dracorex. These were bipedal ornithischian dinosaurs that had hard bony domes on their heads, often complemented with an array of spikes. Dracorex was small with a relatively flat head with small spikes, Stygimoloch was mid-sized with a small bony dome and huge horns, and Pachycephalosaurus was large with a large bony dome and relatively small horns. Together these dinosaurs appear to represent a growth series from juvenile to adult, all grouped together as Pachycephalosaurus, and the evidence can be found in the makeup of the bones.

Even though bones are hard they are not static things. They are constantly being remodeled; the change may be difficult to see from day to day but bone is still constantly being reabsorbed and laid down. The same processes happened in these dinosaurs, allowing for major modifications of the skull.

Looking at the microscopic structure of the skull bones, Horner and Goodwin found that the horns on the skulls they examined started off small, grew large, and then were reorganized as smaller structures around the edge of the solid dome of the skull. The young dinosaurs were not born with adult ornamentation but grew into it over time. Why large spikes were a juvenile characteristic and a bony dome was an adult characteristic, however, is still unknown.

Extreme changes in skull shape during growth can also be seen in hadrosaurs, where what were considered “small” species turned out to be juveniles of already known species, and in horned dinosaurs. In fact, at this year’s Society of Vertebrate Paleontology meeting, Horner and paleontologist John Scannella proposed that Triceratops is a growth stage of the larger horned dinosaur presently known as Torosaurus. This hypothesis has yet to be fully supported, but it does seem that many Cretaceous ornithischian dinosaurs underwent major anatomical changes during their lifetimes. No doubt this area of research will generate much discussion and debate in the years to come.