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Fossil and Forum Friday, Holiday edition
We began the week with our first Mystery Monday for paleoaerie.org with the picture of an interesting Arkansas fossil. Today, Forum Friday will become Fossil Friday as well as we identify the fossil. Did you guess what it was? See if you were right below the picture.
Congratulations go to Allie Valtakis, who correctly identified it as a nautiloid cephalopod. This particular one is Rayonnoceras solidiforme. It has traditionally been placed within the Order Actinocerida, although some workers have placed them into the Order Pseudorthocerida, which is known for their resemblance to the more commonly recognized orthocerid cephalopods.
Commons.wikimedia.org
What are cephalopods, much less nautiloid cephalopods, you ask? Cephalopods are the group of molluscs that include squids, octopuses, and cuttlefish. There are three major groups: Coleoidia, which includes almost all the modern cephalopods; Ammonoidea, which includes almost all the extinct ones and are known for their complexly sutured shells; and the Nautiloidea, which are mostly extinct, the only living form is the Nautilus. The ammonoids and the nautiloids both formed shells. What differs between them is how they made them. Some of those in Coleoidia also form shells, but they have been greatly reduced and internalized, such as in squids, or lost altogether, such as octopuses. For those with external shells, they have the problem that shells don’t get bigger once the mineral is laid down, so they quickly grow out of their shells. They solve this by adding mineral to the front of the opening in an ever-increasing funnel, periodically walling off the back of the living chamber (leaving a small opening for the siphuncle that goes all the way through the shell, creating a series of gradually increasing sections.
The ammonoids are well known in the fossil record, particularly the subgroup called ammonites, having a diverse array of straight, curved, and coiled shells. What makes them unique from the nautiloids is the sutures between sections are wavy, sometimes showing astoundingly complicated patterns. The nautiloids, on the other hand, sport very simple, smooth curves. It is this group in which Rayonnoceras belongs.
newswire.uark.edu
Rayonnoceras lived about 325 million years ago in the Mississipian Period, although nautiloids as a group have been around since the Cambrian Period over 500 million years ago. What makes this particular species so interesting to Arkansans is that the largest nautiloid cephalopod ever found (update: largest pseudorthocerid nautiloid, not largest nautiloid) was discovered near Fayetteville, AR. It was 2.4 m (8 feet) and found in a rock unit named, appropriately enough, the Fayetteville Shale, a unit of dark gray to black shale and limestone, indicative of a warm, shallow marine environment without a lot of sediment input, much like many areas within the Bahamas today.
To recap what we’ve covered over on the Facebook page, we recommended a book discussing misunderstandings in human evolution and another in how evolution affects our health. We saw a hominid fossil hand bone that helped to show how we differed from australopithecines and genetics work that showed us how we didn’t differ from Neanderthals.
We learned how malaria is evolving and why you shouldn’t take medical advice from celebrities. We also bemoaned the airing of a another horrid false documentary about mermaids on Animal Planet.
Emily Willoughby. Wikimedia commons. This file is licensed under the Creative Commons Attribution 3.0 Unported license.
We learned about a new dinosaur named Archeroraptor and new work on dinosaurian growth rates. We also read how the largest volcanic eruption ever caused the greatest mass extinction ever.
We read about genetics work that informed us how flowering plants evolved by doubling their own genes and stealing genomes from other plants. We learned about a “second code” within DNA and why the hype was bigger than the story, but may help us rethink our DNA analogies.
We saw how birds defend themselves against cheaters and learned the first lizards and snakes may have given live birth. We also got some information on how teaching and testing will need to change under the Next Generation Science Standards.
On a final note, this will be the last post this year on paleoaerie.org. Enjoy the holidays and join us in January, when we will be embarking on discussion of the Ordovician rocks and fossils in Arkansas. Over the spring, we plan on discussing several vertebrate fossils found in the state. There are several books and online resource reviews coming up as well. We will be adding to our Scientists in the Classroom and adding several new resources to the links pages. As always, we will be posting a plethora of current news items on Facebook, so stay tuned! In the meantime, tell us what you liked, didn’t like, want to see more of, and any questions you may have.
Forum Fridays and Mystery Mondays
Likely thanks to upgrading computer systems and the joys of trying to figure out new setups and operating systems, there seems to have been a small glitch deleting the post that was supposed to go up Friday, so it is getting posted today. So let’s see if we can make lemonade from the lemon.
On Facebook, I started a new set of posts, in which I post a picture of a fossil found in or could be found in Arkansas and see if anyone can identify it. The first one I put up was of a mosasaur, a huge aquatic reptile that swam around Arkansas seas during the Cretaceous Period. People seemed to enjoy it, so I will be doing this on a regular basis. However, it has come to my attention that many places block Facebook, including a lot of schools. So I will be posting them on the blog. I will try to post a new picture every Monday and will then provide the answer on Friday, giving people the week to see if they can come up with the answer. Don’t worry about being wrong, we learn more from our failures than our successes anyway. You can’t win if you don’t play. So with that, let’s play! here is today’s pic. Can you tell me what it is?
In the meantime, if you missed out on all the stuff we covered on Facebook, here is a brief summary of most of hte stories.
Of the many new fossils and work on fossils that were reported on this month, we saw a new fossil primate that may have been ancestral to lemurs and lorises and giant, terrestrial pterosaurs of doom. We learned about the earliest flowering plant in north America, new crests for old dinosaurs and the promise and perils of resurrecting dinosaurs and other extinct animals..
The poor platypus, he has no stomach (but at least he has poison spurs). John Gould. 1863. Wikimedia.
We learned about evolutionary ghosts, how animals colonize new territory, and how unmasking latent variation within a population can lead to rapid evolution.
Photo by Jonathan Blair. http://tinyurl.com/n4xzv26
We learned how evolution made it easier for people to believe in God than accept evolution and why fanaticism of any stripe can lead one astray. We read a discussion about the importance of scientists in science communication, and why we shouldn’t ignore Youtube. We found help in teaching controversial subjects in hostile environments and apps to help teach hard-to-grasp subjects like astronomical distance.
We learned about how bacteria avoid the immune system to cause disease, how they form an important part of breast milk, and the four billion year history of vitamins. We learned even bacteria have a hard time living deep inside the earth and how viruses can kill even antibiotic-resistant bacteria. We also read a review of a book on evolutionary medicine.
Comb jelly. Wikimedia. Creative Commons Attribution 2.0 generic license.
So, what were the stories you liked? Did it spark any thoughts, either good or bad? Was there anything that you saw that we didn’t mention? Share your thoughts and don’t forget to try your luck with identifying today’s Arkansas fossil!
Forum Friday, or, hrm, Monday Meetings?
It’s the beginning of December and more than a month since we’ve had a Forum Friday, but since most people were either still enjoying their Thanksgiving dinners or fighting through crowds of shoppers, I opted for a Monday meeting. October was a busy month and November followed suit. Most of what we posted on Paleoaerie since the last Forum was a rundown of the Society of Vertebrate Paleontology annual meeting in Los Angeles. A huge amount of material was presented at the meeting, of which we barely scratched the surface. We also reviewed The Big Golden Book of Dinosaurs, a great book for elementary kids.
We covered a lot on the Facebook page. Evolution in medicine got a lot of attention, including a whole online, open-access journal about it. We learned about evolutionary theory being used in the fight against the flu, malaria, HIV, and cancer, twice, no three times! We even learned why we have allergies, and if that isn’t enough for you, we found a whole series of papers on evolutionary theory in medicine for you.
Studies of human evolution had a good showing this month, starting with a new skull of Homo erectus changing our views of our ancestors and a book called “Shaping Humanity: how science, art, and imagination help us understand our origins.” We learned how women compete with other women and how natural selection can be tracked through human populations.
Homo erectus skulls. Courtesy of the University of Zurich
Modern experimentation has demonstrated how life may have gotten started chemically and how clay hydrogels may have helped. We watched the evolution of bacteria in a lab over 25 years. We also learned how evolution can evolve evolvability.
Evolution outdid itself with deep sea animals eating land plants and an amazing mimicry display. We learned why bigger isn’t necessarily better, why monkeys have colorful faces, and that large canines can be sexy.
In addition to all the news from SVP, we learned about two new giant theropods, the tyrannosaur Lythronax and the allosauroid Siats. We also learned about the toothed bird, Pelagornis and pachycephalosaurs. We also learned about research on what modern animals tell us about dinosaur brains. We also saw evidence that the Mesozoic may not have had as much oxygen as we thought.
Dinosaurs weren’t the only fossils of interest to be announced. A new unicellular organism is providing insights into the evolution of multicellularity. The oldest fossil of a big cat and a suction-feeding turtle were found, as well as the oldest known fossil ever, providing evidence of life almost 3.5 billion years ago. We read the beginning of a series on the evolution of whales and how the first tetrapods crawled onto the land. We learned about fossil giant mushrooms and watched the Red Queen drive mammals to extinction.
Putting 3D images of fossils on paleoaerie has always been one of the goals of the site and the potential for this to revolutionize geology has not gone unnoticed. The Smithsonian has taken up the challenge. If you want to learn how to do it, here is the paper for you.
We celebrated Alfred Russell Wallace and American Education Week. Along the way, we listened to the great David Attenborough describe the history of life and Zach Kopplin tell us about his efforts to keep creationism out of public schools in Louisiana.
For educational techniques and resources, we looked at BrainU and a website by the ADE and AETN. We examined the usefulness and pitfalls of gamification. We saw how to build your own sensors and use them in class. We discussed how to change people’s idea of change through business concepts the truth about climate change. We even saw doctoral dissertations via interpretive dance.
Finally, the holidays are fast approaching, so if you are looking for gifts, we looked at a rap music guide to evolution and Here Comes Science by They Might Be Giants.
Do you have any gift ideas to share? Any of the stories particularly pique your interest? Let us know. Don’t just talk amongst yourselves, talk to us.
It’s Big, It’s Golden, and it’s Dinosaurs
The Big Golden Book of Dinosaurs
By Dr. Robert T. Bakker
Ilustrated by Luis V. Rey
Publication date: 2013. 61 pg.
Golden Books, Randomhouse. ISBN: 978-0-375-96679-8.
Do these books look familiar? One is the classic book that most people old enough to be parents grew up on, first published in 1960 and continuing through 1981. The second is the new, Big Golden Book of Dinosaurs, a new, totally updated edition that came out in 2013. The book is written by Dr. Robert Bakker, known by many as the bushy-bearded, cowboy hat-wearing paleontologist of many documentaries and the author of such books as the Dinosaur Heresies and Raptor Red. Illustrations are by Luis Rey, a talented artist already mentioned here due to his work illustrating Dr. Holtz’s Dinosaurs book. Dr.Holtz’s book was written for a wide audience, geared towards children of middle school age and upwards. This book, like its predecessor, is geared for elementary kids. So it is not as detailed, but it is even more lavishly illustrated and will definitely hold the interest of younger kids.
From the front cover to the last page, those who know and love the original book, will find it echoed here, but updated with the latest information. inside the front cover is a map of the world as it existed in the Triassic and early Jurassic, with dinosaurs dotting the landscape, showing where various dinosaurs have been found. The map is matched on the inside of the back cover with a Cretaceous map. Both maps have the names of each of the dinosaurs illustrated so you know what you are looking at. There is also an index and handy pronunciation guide for all the animal names.
While the book is of course heavily weighted towards dinosaurs, like the previous book, it does not focus entirely upon them. In the brief introduction, it makes a point to place the dinosaurs in context as part of an evolving ecosystem, not as isolated creatures. The book then dives into the Devonian seas,introducing us to the fish that began the walk towards becoming landlubbing tetrapods (animals with four legs). It continues with a few pages on the Carboniferous and Permian Periods, with giant insects, early amphibians and reptiles, and even animals like the iconic Dimetrodon, properly identifying its kin as ancestral to modern mammals, even explaining key features showing it’s related to us. Only then do we get to the Triassic, the beginning of the Age of Dinosaurs and even then, it starts the discussion with pterosaurs and the ancestors of crocodylians. After a mention of the earliest dinosaurs, it then mentions the proto-mammals.
Finally, we reach the Jurassic Period and it is here that dinosaurs take center stage, with gigantic, long-necked sauropods and other well-known dinosaurs. Even so, they don’t forget the small, mouse-like early mammals under foot. After a brief interlude to discuss the great sea reptiles that appeared during this time, as well as the pterosaurs, that were now much bigger and diverse than in the Triassic, they return to a discussion of dinosaurs, this time focusing on a bit of history explaining how our views have changed over the decades.
The book moves then into the Cretaceous, showing how dinosaurs adapted to diverse environments, such as the sand dunes of central Asia to the snows of the poles. There is a chapter on different ways dinosaurs communicated with each other, including singing, after a fashion, much like birds and animals call to each other today, although he goes a bit overboard in this area and speculates beyond what most in the field would say is reasonable. Of course, no elementary book would be complete without a chapter devoted to Tyrannosaurus rex and its battle with an armored herbivore, in this case, the ankylosaurid Euoplocephalus and a battle with Triceratops. While the book makes much of the use of horns and frill by the Triceratops in battling T. rex, they were almost assuredly evolved to battle other Triceratops as dominance displays, like bison or antelope today, although that of course, doesn’t rule out their use as defensive weaponry against predators.
There is the required chapter on dinosaur extinction and it does a good job of mentioning several possibilities. However, it gives a bit of short shrift to the most accepted asteroid hypothesis and a bit more space to Bakker’s favorite hypothesis of disease, which is almost assuredly not true as a hypothesis of widespread extinctions on such a large scale. To his credit, he ends with the likely possibility that no one hypothesis is sufficient for explaining everything.
The book ends with what animals actually benefited from the extinction, that being mammals. The book ends with noting that not all dinosaurs died out and acknowledging the influence that dinosaurs had on the evolution of early mammals, thereby connecting the story of the dinosaurs to us. Besides the great illustrations, that I think, is the key strength of this book, never letting the reader forget that dinosaurs were but a part (a big, incredibly impressive part) of a bigger ecosystem, with each piece influencing the others. No group was isolated from the others, all are interconnected.
Overall, while I had a few minor quibbles, as i mentioned above, I can definitely recommend this book for any elementary library. Some middle school kids will like it too, although those older than that will likely be reading it for nostalgia of the original book, who will find this version a worthy successor.
Other than the image of the 1960 book, all images are illustrations from the book.
Day 4 at SVP
Day 4 and the last day at SVP. After this, we will return to our regularly scheduled sorts of posts.Another day of talks and poster sessions, the last chance to meet friends and colleagues and discuss what you’ve heard and what people are doing. Although frankly, I think most people are tired and ready to go home by this point. Some people thrive on the highs of shared creativity and knowledge and find the end of the meeting and going back to regular work depressing, I think the most common reaction is the feeling of being rejuvenated by the meeting, so that you can’t wait to go back and start developing the new ideas created at the meeting, the chance to put those creative juices to work before the distractions of everyday life dry them up.
A lot of people don’t like having their talks on the last day. People are going home, they are tired, their attention flags, but this meeting showed a strong turnout for the last set of talks. The symposium scheduled for today was “Patterns from the poles: biodiversity and paleoecology of high latitude fossil vertebrates,” which I, at least, found interesting and worth attending. I didn’t attend too many of the talks though, because there was also a session on the evolution of early birds, which I found even more interesting, as well as a session on mammals, which had several talks discussing how different mammal groups adapted to climate change in the past. Several talks introduced new fossils and what they contributed to our knowledge of evolution within those groups, such as a new Devonian fish from Siberia, the first pterosaur from Antarctica, a new sauropodomorph (early versions of animals that would become sauropods, the oldest mammal from Antarctic and a new Arctic camel, new birds, seals, sirens, dolphins, and whales. All in all, good reasons to stick around.
Anchiornis_martyniuk, wikimedia
Rui Pei reported on a new specimen of Anchiornis, the first animal in which fossil evidence in the feathers was used to determine coloration. Anchiornis lived 10 million years before Archaeopteryx and there has been some debate about whether it was a true bird or still a non-avian dinosaur. Pei’s analysis of the new specimen indicated that Anchiornis was a troodontid, so not quite yet a bird. This is another great example that the transition between birds and other dinosaurs is so well documented that the line is an arbitrary classification with no biological relevance. Speaking of feather colors, William Gearty found new ways to study the melanosomes in the feathers providing colors, finding that, in addition to color, he could tell color gradients as well. he also concluded that melanosomes stiffened the feathers, making them more resistant to wear, but also carried more bacteria, thus representing an additional resource cost for the animals (some of this work can be found online at PLOS One).. Justin Hall found that feather asymmetry, long thought to be important for flight, turned out not to have the aerodynamic significance we thought, as it didn’t really affect the ability to fly. Ashley Heers found trade-offs in locomotor ability: the more investment in wings, the less was put into the legs, and this trade-off could change as the bird grew so that chicks may emphasize the wings or legs while the adults emphasized the other.
Cryolophosaurus, Royal Ontario Museum. Wikimedia.
Several studies showed the difficulties inherent in paleoecology interpretation. Peter Makovicky found that the horned ceratopsids showed different growth rates between northern and southern populations, the duck-billed ornithopods did not, and the carnivorous theropod Cryolophosaurus showed different growth rates in different areas of the same body in the northern individuals, but not in the southern individuals. According to Bergman’s rule, we should expect to see animals get bigger and stockier the farther north they are found. Anthony Fiorillo found that the small troodontids followed the rule, but northern individuals of the large tyrannosaurs were only 40% the size of the southern ones. In this case, it is likely that resource supply kept the tyrannosaurs smaller. Patrick Druckenmiller reported on a diverse Arctic dinosaur fauna including toodontids, dromaeosaurs, thescelosaurs, hadrosaurs, pachycephalosaurs, and tyrannosaurs, despite mean annual temperatures near freezing. While similar to southern forms, all the species were different, indicating a discrete, provincial ecosystem. John Tarduno argued that the presence of champsosaurs (a type of early crocodylian) and turtles indicated the weather was too warm for ice to be present even during winter, but as proven by an earlier talk, we know this is incorrect (a great example of science correcting itself). He proposed volcanism forming a series of shallow, freshwater connections between North America and Asia during the latest Cretaceous allowing interchange between the continents, which will need more study to determine if that proposal is true. Judd Case found that even though modern fish fauna show a drop in diversity with lower temperatures, thisi was not the case in the Cretaceous. As the temperature in the Cretaceous dropped 8-10 C in the Antarctic oceans, the fish didn’t really change, although marine reptiles increased in diversity while the ammonite diversity dropped.
Figure from Fletcher et al. 2010, showing FEA analysis, indicating stress points near the joint.
Rodrigo Figueiredo presenting evidence that predators who pursue their prey (as opposed to ambush predators attacking large prey and those that pounce on smaller prey) may not have evolved to go after herbivores, but to prey on the pounce predators themselves, much like wolves will sometimes hunt foxes and weasels. Michael Greshko presented a study finding that herbivores known as generalists (able to eat a wide variety of plants) mostly consist of different individual specialists who eat only a narrow range of foods. This is rather like why a pizza buffet needs to stock a lot of different types of pizza even though any particular customer may only eat one or two different types. Speaking of eating, Emily Rayfield gave a possible answer to why mammals reduced the number of bones in the mandible to just one, as opposed to having several bones in the lower jaw like other groups of animals. Using Finite Element Analysis, an engineering method designed to test mechanical strength of materials, found that the one bone provided a stronger bite while reducing stress. Alistair Evans used a program called GEOMAGIC to study tooth shape in early mammals and predict what tooth shape should be like to help sort out all the isolated teeth for which we have no idea what they belong to. in this way, he is making predictions of fossils that have not yet been discovered.
Gephi.org BON graph
In addition to the software programs mentioned previously, several others were mentioned in talks this day. Most biogeography methods these days are done using phylogenetic methods to help inform how animals spread out across the globe, but Chris Sidor presented Bipartite Occurrence Networks (BON), using Gephi to visualize the patterns, which just uses locality connectedness and found that therapsids (proto-mammals, aka mammal-like repties) were pretty widespread and cosmopolitan before the Permian extinction event, but became much more provincial and limited in range afterwards. Paul Upchurch used TREEFITTER to map pterosaur biogeography, finding support for sympatry (speciation within the same region) with an origin in eastern Asia. Diego Pol used Ancestral Area Reconstruction methods to conclude that dinosaurs probably originated in South America, along with most, but not all, mammals, but crocodylamorphs originated in China. Graeme Lloyd used GEIGER to study evolutionary rates and Akinobu Watanabe used PERDA (Polymorphic Entry replacement Data Analysis, a script running in TNT, a phylogenetics analysis program) to simulate poor sampling of phylogenetic data, finding that if a trait, or character, has multiple possibilities within a single species, it seriously messes up results unless multiple individuals covering all the possibilities are included in the analysis. John Alroy found that no current method is very good for finding the first appearance of taxa, but Bayes Theorem methods, such as used in MrBayes, produce better estimates of extinction times.
Figure from Sansom and Willis 2013 showing fossilization study results.
The last two talks I would like to mention are from Robert Sansom and David Grossnickle. Sansom found that loss of soft tissue characteristics resulted in changes in cladograms drawn from the data for vertebrates, but not for invertebrates. In other words, if one only looked at hard parts, the evolutionary relationships changed, and more often than not, made the animal appear to be more ancestral than it really was. This occurred even if the characters were recorded as unknowns and not simply listed as absent. Grossnickle looked at morphological disparity in Mesozoic mammals, i.e. the diversity of body form. What he found was that most Mesozoic mammals were carnivorous/omnivorous, with a low level of diversity which gradually increased until the middle Cretaceous. At some point in there, they hit a botttleneck. Their diversity crashed and, while it did start going up again,never reached the previous diversity levels until after the K-T extinction event. What is interesting about this is that pretty much everything else was diversifying, while mammmals were not. Another interesting thing about this is that according to molecular data, mammals were diversifying, so the apparent diversification did not show up as morphological diversity.
This is the end of my discussion about the science presented at SVP. There were so many more talks and posters that I did not mention and i make no claim that the ones I mentioned are even the best or most important, nor are they even all the ones I attended and learned something from, but it would take me until the next meeting to discuss all of them. The point is that meetings like this are incredibly fascinating places to see what is going on in science right now. Anyone who thinks science is a bunch of stale facts in textbooks or that scientists even pretend to have all the answers is seriously mistaken. The search for truth is asymptotic, you can get ever closer to a totally clear understanding of reality, but you will never reach it. Science is all about going over the data, tossing out ideas that don’t succeed and developing ones that do, with each step opening up new avenues of exploration.
Steven Spielberg on set of Jurassic park. Spielbergfancluc.com
I will end this discussion with the awards banquet held on the evening of the last day. During this banquet, we are told how much the auction collected to support the society, important news, memorials for those we lost recently, and people are recognized for their hard work and contributions to the field of vertebrate paleontology. Students are awarded their prizes and scholarships they have won, artists are awarded for best art in different categories, and people are recognized for outstanding careers that have progressed the field. This year, one of the biggest awards went not to a scientist, but to a science advocate. Perhaps because the meeting took place in Los Angeles, special recognition went to Steven Spielberg, for the money he has donated to the Jurassic Foundation and other places to support paleontology research and education and for the Jurassic Park movies, which brought paleontology to the center of the public eye and has inspired many to enter the field and make their own contributions. Officially, the meeting ended here. There was an after-hours celebration, which is always fun from what I hear, but I was beat and had a plane to catch early in the morning, so I called it a day. Until next year!
Day 3 at SVP
Another day at SVP, another boatload of information. Some may be wondering why I am devoting several posts to this meeting,when it may seem not as relevant to the general public. Fair question. people not actually doing science in an academic setting rarely get a chance to see anything about what it is like. Science is often presented as a list of facts, but that is only part of the story. Science is a dynamic endeavor, never being satisfied with an answer, always working on the things we don’t know and revisiting the things we thought we knew to see if they still hold up under the new information. Science gets things wrong all the time, but this process of study and review and critical examination reduces the margins of error. Not all things that are wrong are equally wrong, rejecting evolution in its totality is a whole other category of wrong compared to disagreements about the rates of evolution in a particular lineage. No one in science who examines the evidence seriously disputes evolution or that dinosaurs existed, but exactly how evolution works, how dinosaurs lived, exactly who is related to whom; these are questions that people struggle with. With each new study, the path moves closer and closer to the truth, each time having the possibility of opening up whole new avenues of exploration we had never thought of before. That is what these meetings are all about, bringing minds together for new solutions to old questions and for finding new questions to ask about old solutions. What goes on at meetings is a glimpse behind the curtain of published papers and distilled textbooks, putting human faces onto that quest, faces that are, more often than not, students working together and with more experienced people. Most science is done not by white-haired old men in the lab, but by young, energetic students with a zest for learning. And there is so much more to do.
In the previous two days, there were collections of talks called symposiums, devoted to specific topics, such as on ontogeny and the la Brea tar pits, including a preparators symposium on fossil collection and preparation techniques. Friday included a special symposium on the tempo of evolution and dating the fossil record. Samuel Bowring presented the EARTH-TIME Initiative, an opportunity to date the stratigraphic record to a precision never before seen, allowing measurements as refined as +/- 20,000 years all the way back to Triassic times (>200,000,000 years ago). That is a resolution of 0.01%. The remaining talks were about research on specific areas and times contributing to that increased precision.
Tar pits at the Page Museum. http://www.tarpits.org
Terry Gates looked at cranial ornamentation in theropod dinosaurs, finding only larger theropods used bony ornamentation and that if a lineage developed it, the lineage quickly developed larger species. So the question now is why were bony cranial ornaments only selected for larger body sizes? Yuong-Nam Lee reported on new fossils of Deinocheirus, an enigmatic fossil previously known only from one set of huge arms, which allowed them to determine it was the largest ornithomimosaur ever found, sporting a large sail on its back near the hips, something like a small spinosaur sail. Picture a giraffe-sized ostrich, with a sail on its back, giant arms with huge claws, and a big,chunky tail. On second thought, maybe not so much like an ostrich, after all.
Deinocheirus. By Nobu Tamura.
Other dinosaur reports include Ashley Morhardt, who reported that Troodon had the largest encephalization quotient of any non-avian dinosaur (i.e. it had a big brain). Most of its brain was made of the cerebrum, which not only makes a reasonable case for it being the smartest dinosaur, but supports a mosaic model of brain evolution, meaning that different parts of the brain evolved at different rates. Amy Balanoff discussed the evolution of oviraptorosaur skulls and brains, showing larger cerebrums than most other dinosaurs, but reduced olfactory tracts, so they were similar to birds in having a relatively poor sense of smell. Walter Persons reported on fossils showing that Microraptor ate mostly fish, as well as small mammals and birds.
A session devoted to mammals had several interesting talks, such as one by one by Ross Secord, who concluded from his research that the body size increase seen in horses was related to warmer temperatures allowing an longer growing season causing increased availability of grasses, making up for the lesser nutritive value of grasses compared to other plants. I would argue however, that a shift to eating hard-to-digest grasses would result in increased body size not through increased availability, but to increase digestion efficiency. Horses are what is known as hind-gut fermentors, which is less efficient than the foregut fermentation seen in ruminants such as cows. This mode of digestion is more efficient at higher body sizes, allowing more time for digestion. Lindsey Yann found that horses were too much of generalist feeders to be useful for paleoclimate reconstructions, but different camel species were more specialized and could used to make determinations of relative aridity and plant cover. Rebecca Terry found that interactions between mouse species had at least as large an effect on population sizes as climate, with different species reacting differently to resource changes. Thus, there is no easy answer to predicting how species will react to climate changes because they cannot be looked at without understanding interactions throughout the entire ecosystem. Much of this sort of work uses MIOMAP and FAUNMAP, which are similar paleontology databases to the Paleobiology Database, but limited to mammals in North America and so may be more complete for these types of studies.
Hemiauchenia, an early North American camel. Drawing by Gavin McCullough.
Brady Foreman discussed ways to interpret the completeness of the fossil record based on river deposition patterns and Patrica Holroyd discussed the “missing marsupial problem,” finding that because most eutherian mammal fossils are identified to species level and most marsupial fossils cannot identified beyond “marsupial,” there is a taxonomic identification bias in the literature and thus, species diversity studies.
Three other studies I would like to mention are about archosaurs, the “ruling reptiles,” including crocodilians, dinosaurs, and birds. Brandon Peecook looked at the bone microsturucture of Nyasaurus, which was either the earliest known dinosaur or the closest basal archosaur to it, and found that it had elevated growth rates compared to other reptiles, indicating that all dinosaurs may have had faster growth rates from the beginning. John Sarrazin reported that crocodilians and birds both use unidirectional air flow through lungs,as opposed to bidirectional like mammals, which uses a completely aerodynamically controlled system with no structural valves, so in all likelihood, the ancestral archosaur had these characteristics as well. Finally, Jennifer Nestler found that cold weather is not what limits the range of alligators. Rainfall contributed more than 60% to range limitations, most of the rest comes from warm weather during the summer providing long breeding seasons. Only 0.4% of the factors limiting their range could be attributed to cold weather limitations. Something to think about as global warming causes longer summers with elevated rainfall in the eastern United States.
Air flow in a croc lung. d = dorsal, v = ventral. Figure 10 from Schachner et al. 2013. PeerJ 1:e60
At the end of the day, after the talks and the poster sessions, this is the day for the annual auction, to raise funds for the organization that can be used to fund research and travel grants for students in the upcoming year. The auction consists of two parts, a silent auction and a live auction. In the silent auction, everyone has two hours on which to bid on the objects they want and the last bidder wins, much like alive version of eBay. The auction is filled with a wide array of donated items, everything from rare books and artwork to hand-knitted dino-themed baby socks, whatever people are willing to donate. After the silent auction comes the live auction, usually filled with more expensive, one-of-a-kind items, such as original artwork or the original copy of O.C. Marsh’s dinosaur monographs. I have even seen the services of a field cook and her personal field kitchen for a season get auctioned off. The auctioneers always have fun with it, usually dressing up in costumes. you never know who is going to be serving as auctioneer, it could be a zombie, King Tut, or Superman, but regardless, it is an entertaining spectacle.
Auction committee for SVP 2013. Photo by Neffra Matthews.
An end to another day, only one more day to go, before everyone packs up to go home, or off to their next meeting, or a museum to do research, wherever their path leads them.
Day 2 at SVP
Another day, another long list of talks and posters to see. Here is a brief synopsis of the talks I attended. I only wish I had the time to fully discuss everything that went on and all the material covered, but that would take volumes of material and far more time than I have. As before, if any of the talks sound sufficiently interesting that you want more information, please ask and I will discuss them in more detail. I realize that there are a lot of terms and creature names that may not be familiar to all readers, but the greatest learning takes place when one asks questions, so ask and ye shall receive.
Adam Huttenlocker showing fossils to kids at the Burke Museum. Photo by Lara Shinn.
The big session for today was for the Romer Prize. Alfred Romer one of the most influential vertebrate paleontologists of the 20th century, so every year, SVP awards the Romer Prize to the best presentation by a predoctoral student. A student usually applies within a year of completing their PhD. Those that successfully apply give a talk in the Romer session at SVP, which are voted on by the prize committee and awarded at the end of the conference. It is the highest honor a vertebrate paleontology student can win and so is quite an honor. This year went to a friend of mine I went to grad school with by the name of Adam Huttenlocker.
The first Romer talk I attended was by Stephen Brusatte, who talked about theropod dinosaur phylogeny, finding that while there is good support for a number of relationships in the theropod lineage, we still don’t have a good handle on how the early coelurosaurs, such as tyrannosaurs and ornithomimids, fit into the theropod family tree. He was able to conclude, after a detailed analysis of birds and their closest nonavian dinosaur relatives, that there is no real distinction to be made between them that truly delineates birds from other dinosaurs, giving further support to the dinosaur-bird hypothesis. Nevertheless, once birds did evolve, they evolved quickly, rapidly diversifying. Stephanie Drumheller looked at bite marks to see if you can tell the difference between crocodylians by what damage they leave on the bones. Thomas Evans looked at literally thousands of bones in rivers and found that what we have traditionally expected bones to look like after being carried downstream did not really match the reality at all, forcing us to have to rethink our assumptions of how much we can really say about fossils based on their condition. Adam Huttenlocker examined the “Lilliput Effect” after the Permian extinction. It has been noted that after mass extinctions, animal body sizes decrease, but exactly why that occurred was unclear. What Adam found was that selective extinction of the larger, faster-growing groups was the best explanation in this case. One might ask what other possibility might there be, which would be that all the animals simply got smaller, with some going extinct, but Adam found that smaller species did not alter their size through the extinction, they just survived when the large, fast-growing species died out. Neil Kelley was able to determine, in large part, the diet and feeding behaviors of most ichthyosaurs based on their morphology. Stephan Lautenschlager did a detailed study of therizinosaurs found that having beaks reduced stresses on their jaws and their famous giant claws were likely used to hook and pull vegetation, not for digging or fighting (at least, not primarily). Yasuhisa Nakajima used 3D micro-CT analysis to determine changes in bone growth and how much that can tell us about growth in extinct animals and James Neenan provided the first complete phylogeny of placodonts, the earliest group of marine reptiles.
Blood supply in the turkey. By William Porter.
Dinosaur noses got a lot of attention this meeting. William Porter mapped blood circulation in the dinosaur Camarosaurus, A.W. Crompton studied the evolution of turbinates in the nasal passages of early therapsid mammaliforms, indicating that they may have originated as a countercurrent heat exchanger to help regulate body temperature. Tomasz Owerkowics also discussed the role of turbinates in mammals in thermoregulation, but found they do not serve that purpose in birds or other reptiles. Along the way, they discussed the evolution of the different breathing apparatuses in mammals and reptiles. Robert Eagle also looked at dinosaur thermoregulation, but did so using carbon and oxygen isotopes measured together, which indicated a mammalian level body temperature for sauropods, but somewhat lower for oviraptors (although still higher than modern reptiles). Having large brains is often linked to higher metabolism and both ornithomimimosaurs and troodontids have been considered to have large, almost avian-like brains, but Harry Jerison found that at least their forebrains, while large for most dinosaurs, were still lower than avian forebrains. Going back to therapsids and the permo-triassic extinction, Jennifer Botha-Brink found that therapsids showed reduced life span and earlier reproductive maturity after the extinction event, consistent with what one might expect from populations that lived through an ecological catastrophe with reduced resources.
In strictly morphological evolution studies, Gabriella Sobral found that the fenestrated middle ear, which helped improved hearing capabilities, was not a unique event, but evolved independently six times within dinosars alone and was even rather inexplicably lost in stegosaurs, ankylosaurs, and oviraptors. Henry Tsai looked at hip joints in saurischian dinosaurs and found the femur did not fit the hip socket very well, indicating a lot of soft tissue must have been present in life and that the amount of soft tissue increased as the animals got bigger. Nicholas Campione came up with a new way of estimating body mass for bipeds to get around the fact that the standard equations were designed for quadrupeds and don’t work all that well for bipeds. It turns out that a simple correction factor of the standard equations worked fairly well, simply multiply by the square root of two. now to figure out just how well that really works and why. One potentially confounding factor is that it was based on living birds. I doubt it would hold true if used on say, a kangaroo. Finally, the last talk I want to mention was by Kevin Padian, who after discussing the earliest known bats, proposed that they never glided, but instead used their early wings to make a fluttering, control descent from trees. In his view, bats evolved from mostly terrestrial forms that ran up into trees to avoid predators (much like Dial‘s talk of the previous day), were insectivorous, and jumped out of trees to flutter farther and farther distances. He openly admitted this part was currently speculation and will need much more evidence before it should be accepted as definitive, but was a plausible hypothesis which can be tested, which I think is the mark of a good scientist, clearly delineating between what we know and what we think, between fact and a possible explanation.
So what of this, if any, looks interesting to you? What would you like to know more about?
Day 1 at SVP
I attended the annual meeting of the Society for Vertebrate Paleontology (SVP) last week. This is the yearly meeting where those studying anything with a backbone, from fish to furballs get together to talk about what they have been doing and see what others have found (although admittedly, most of the press goes to dinosaurs). Over the next few posts, I will share brief snippets of what I learned. If you read anything that sounds particularly interesting to you and would like me to discuss it in more detail, just let me know in the comments section and I can expound on the topic.
So what does a scientific meeting like this look like? There is always a dealers’ room, where you can find an array of book publishers, such as Indiana Press and CRC Press, and supply companies, such as Paleo-Tools and Bone Clones, and many others all hawking their wares. You will meet artists such as Luis Rey, learn about what’s going on at different publications, such as PLOS One, and upcoming meetings. There are the business meetings, social events, and award banquets. There are field trips to local paleontolgical sites (this meeting was in Los Angeles, so the La Brea tar pits and the Los Angeles Natural History Museum were highlights). There is also the chance to converse with paleontologists from all over the world, a venue wherein colleagues can talk face-to-face and forge new connections, where students can get their feet wet presenting at an international conference and talk to students of other professors to learn about potential graduate and post-graduate opportunities, which professors make good mentors and which ones to avoid. And of course, there are the talks and poster sessions, where you can hear about the research people are doing right now. If you want to know the current state of the field, this is the place to go. Every day for four days, three sessions run concurrently, each covering 16 talks a day, plus over 120 posters are presented every day. By the end of which, if you haven’t found enough new information to send your brain into overload, you simply haven’t been trying. This is also a relatively small meeting, with only 1500 or so attendees, unlike some scientific societies which have meeting attendances over 20,000.
Bosch Institute Neuroscience meeting, 2007. This is a bad design for meetings. Please, just stop.
Before I get into a short recap of the talks I attended (there were many more I would have liked to attend, but I have not yet perfected cloning myself), I will digress a moment for a quick comment about the meeting room setup. My first thought upon seeing the room arrangement was Happy day! All the meeting rooms are right next to each other; not on a different floor, on the other side of a giant building, in another building, or in another facility entirely, unlike some other meetings I’ve attended. This makes popping from one session to another to see different talks much easier. The downside to this is that hundreds of other people all have the same idea and are trying to go through the same hallway, trying to get around the other attendees who are chatting with friends and colleagues. For those of you that are accustomed to New York subways, this is no big deal, but for some of us, it can be a bit claustrophic as personal space shrinks to microscopic proportions. The other rant I have is that, after all this time, they still have not learned how to lay out a room for the talks. They insist on preparing the rooms as though everyone will calmly file in before the talks and sit there until the break, providing long rooms with the speaker at one end and two long columns of interlocking chairs set in rows up to 20 seats long. however, this is a scientific meeting with many short talks. people stream in and out constantly. So what happens is that all the edge seats are quickly taken and great, yawning chasms of emptiness are left in the center. Why no one ever thinks to place the speakers in the middle of a long wall, with many columns of seats with no more than 6-7 seats to a row, allowing ample space for people to move, is beyond me. They might not be able to put as many seats in, but that hardly matters if no one can get to the seats in the first place. Now on to the talks!
Sauropod nest, by Mike Ellison
In the first session, all the talks dealt with the problems of ontogeny in interpreting the fossil record. Ontogeny, how an animal grows from fertilized egg to old age, can cause several problems in the fossil record. When all you can see is a fossil, it can be very hard to tell if you are looking at an adult or juvenile. Many animals can change so much during development that the juveniles can look like completely different species. Hans Larsson presented about a possible way to figure out rough ages of an animal by looking at how different bones in the skull covaried, or how they changed shape in relation to each other as they grew. Jack Horner warned against assuming an animal is full-grown unless you have solid evidence of that from the bones across the skeleton and Mark Goodwin showed how difficult that can be with pachycephalosaurs, but Holly Woodward found that at least some dinosaurs reached sexual maturity long before they reached “adult” size and in fact, never stopped growing, so it is important to keep in mind just how one defines “adult.” David Evans showed the problems of using juveniles and adults in the same phylogenetic analysis, in that the relationships of species identified using juveniles were very ambiguous and unstable, often showing up as more ancestral than an adult of the same species, sometimes substantially so. John Scannella found that using just one juvenile specimen of Triceratops in a phylogenetic analysis resulted in that specimen not being identified as a ceratopsian at all, but if a sufficient number of juvenile specimens of different ages were included, they all fell out together in their expected relationship. This indicated the ontogeny problem can be dealt with if you have enough samples, as well as indicating what characters are newly evolved versus being evolutionarily stable. Zachary Morris extended this to show that not all individuals grow up the same way, there was no set pattern of development that all individuals within the same species followed to adulthood, so trying to order specimens into an ontogenetic sequence requires a large sample size. Also, contrary to an earlier research that got a lot of press, Torosaurus is probably not the same species as Triceratops. Robert Reisz showed very fast growth in prosauropod embryos and P. Martin Sander estimated that sauropods could grow to sexual maturity in 16 years, attaining 90% of their maximum size within 32 years. This comes out to an average growth rate of 4 kg/day, which is similar to modern large mammalian herbivores, but he cautioned this was likely overestimating the ages and underestimating the growth rates. Ken Dial discussed the role of predation in the development of flight, with evidence indicating that if predation pressure was relaxed and there was sufficient food resources, birds commonly became flightless.He made the interesting point that everything is a transitional environment; that to truly understand an organism,one has to examine all aspects of their habitat and you can’t afford to get to narrowly focused. Denver Fowler found that animals occupying different niches at different ages were more susceptible to extinction. Caroline Stromberg found that, contrary to popular belief, the development of grasslands didn’t actually correlate very well with high-crowned, hypsodonty teeth.
Wikipedia.org
Sandy Kawano looked at how locomotion changed between fin and feet and found that the total forces between front and hind limbs was fairly constant, but acceleration came from the pectoral fins at first, but as the hind limbs developed, more of that motive force came from the hind legs, with the front legs taking on more of a regulatory role guiding maneuverability. Karen Sears found that limb evolution became more modular, in that different parts of the limb evolved at different rates and times, so that each part could be considered as evolving relatively independently, with higher levels of evolution near the ends of the limbs. Paul Sereno discussed the evolution of the coracoid bone in the shoulder and how its loss in almost all mammals created a more flexible and faster, but weaker joint. He opined this is why bats don’t grow to the size of birds or pterosaurs and that it allowed dinosaurs to get bigger and carry more weight than mammals.
Model of air flow through the nasal passages of Majungasaurus. Image and work by Jason Bourke
Ali Nabavivadeh reported on his studies on the evolution of jaws in ornithischian dinosaurs, finding they talked the problem in a variety of different ways. Lucas Spencer noticed that all early ornithischians were in Gondwana and that dispersal explains more of their biogeography than vicariance (speciation via the emergence of physical barriers). Mark Loewen reported on the biogeography and phylogeny of ankylosaurs, while Victoria Arbour discussed the evolution of the ankylosaur tail club. Philip Currie reported on the smallest known articulated ceratopsid fossil, while Andrew Farke reported on ceratopsian biogeography. Thomas Carr found evidence to support anagenesis (direct ancestor-descendant relationships) in some tyrannosaurs, but not all, while Brandon Hedrick found that fossilization processes made one species of psittacosaurs look like three different ones. Jordan Mallon found little evidence in pachycephalosaur skulls to indicate they lived in upland areas, as is often stated, and Jason Bourke did some very nice computer modeling showing how turbinates (structures within the nasal passages often associated with endothermy, aka warm-bloodedness) work to channel air through nasal passages,using that to find support for respiratory turbinates in pachycephalosaurs.
This all only recounts brief snippets of the talks I attended on the first day and doesn’t include the many posters I looked at. I will cover Day 2 in my next post. If you want more information on any of these snippets, leave a comment and I will be happy to expound upon them.
Forum Friday, winging our way to LA
Paleoaerie is off to Los Angeles next week to attend the annual meeting of the Society for Vertebrate Paleontology. If it has a backbone, it will be discussed there (if it is still alive, the discussion will be linked to fossil relatives, but I didn’t want to unnecessarily limit it, because I’ve seen gators, chickens, dogs, sharks, and everything in between discussed there in relation to their fossil ancestors; I’ve even heard and presented on bacteria, insofar as they help make fossils).
As a result, I’ve only done one blog post on Paleoaerie since last Forum Friday and I won’t be able to post anything other than maybe comments about the meeting next week, so I wanted to get a forum post out before I go, although I realize that some of you reading this may not see it before Monday, what with the lateness of the hour this got posted.
So without further ado, here we go. On Paleoaerie, we talked about the book, Scaly spotted feathered frilled: how do we know what dinosaurs really looked like?” by Catherine Thimmesh, a great book for any budding paleoartist you know.
Over on Facebook, we celebrated Member Night at Mid-America Museum and their new dinosaur exhibit, Reptile Awareness Day, and Geologic Map Day. We learned about the Backfire Effect and why telling people facts is not always convincing and ways to frame your arguments that may work better. We warned against the ResponsiveEd curriculum, as well as Stephen Meyer’s book, Darwin’s Doubt, with some interesting new studies on the preCambrian life leading up to the Cambrian explosion.
We learned more about Tyrannosaurus rex and what we still have to learn, and we met Joe the dinosaur, the most open-access dinosaur ever. We learned how rapid evolution in one organism can cause a cascade of reactions throughout the ecosystem.
We saw a whole host of dinosaurs in 3D, as well as horses and a lot of cool videos from the Science Studio. We saw a new animation explaining how the evolution of life affected the early atmosphere, oceans, and which rocks were formed.
We learned about the usefulness of evolution in medicine, how allergies can save your life, and that sharks, contrary to popular opinion, suffer from cancer just like the rest of us. We also saw a robot made completely out of prosthetics made for humans. Where will we go from here and how much farther can we go?
May your Halloween be filled with spooky fun!
Why do artists draw dinosaurs the way they do?
Scaly Spotted Feathered Frilled: How Do We Know what Dinosaurs Really Looked Like?
By Catherine Thimmesh
Publication date: 2013. 58 pg.
Houghton Mifflin Harcourt. ISBN: 978-0-547-99134-4.
Author: Catherine Thimmesh is an author of several books aimed at children in elementary to middle school. Her books have primarily focused on people, particularly women, doing science and politics, while bringing a wealth of information along with the human stories. As a result, her books should appeal to many people, helping them draw personal connections to the material. Two of her books, Girls Think of Everything and The Sky’s the Limit, have been listed as Smithsonian Notable Books, the latter book also listed as an Outstanding Science and Social Studies Trade Book for Children in 2002. Her book, Team Moon, discussing all the people besides the astronauts that made the moon landings a success, won the Sibert Award in 2007.
Iguanodon by Waterhouse Hawkins, 1850s
Illustrator: The book is beautifully illustrated by several well-known paleoartists, including John Sibbick, Greg Paul, Mark Hallett, Sylvia and Stephen Czerkas, and Tyler Keillor, as well as Charles Knight, the artist who created the classic pictures shaping the view of dinosaurs for more than a generation. Moreover, there are pictures of skeletons, sketches showing reconstruction from bone to skin, as well as Greg Paul’s classic silhouetted skeletons. As an added bonus, she includes a page at the end with a paragraph about each artist and a fun fact about each one. For instance, Mark Hallett was the person who coined the term “paleoartist.”
I have mentioned this book previously from a review by Brian Switek (for a librarian’s perspective, try the SLJ review here), but I finally got my hands on a copy so I can provide my perspective on it and I have to say, I agree with the other reviews. this is an excellent book well worth including in any elementary or middle school library or classroom. If you know someone who likes dinosaurs and likes to draw, they will like this book. This book gives a great discussion of how artists bring fossils to life, using new discoveries that are changing our views of how dinosaurs looked and comments straight from the artists crafting those visions.
The book wastes no time, providing information on the inside covers. At the beginnig is a timeline showing the different Periods of the Mesozoic Era, with a short description of the overall climate, apleogeography, and notable fauna and flora of the time for each Period. Inside the back cover is a breakdown of the three major dinosaur groups, with a few general facts describing the dinosaursin each group and listing several representative dinosaurs for each group (along with page references for where they appear in the text). Other things that puts the book on my recommended list is a nice index, glossary, and references; things not often found in childrens’ books, which makes this book a cut above. This book does not take the sadly all too common tack of using the “it’s a childrens book” excuse to talk down to the audience and not worry about the facts 9except for one point mentioned by Switek which I will get to later).
Seismosaurus. Mark Hallett, 2006
The book starts with a discussion of questions the artists ask about the fossils themselves and what scientists can determine from them, such as what can the bones tell us about how they moved and what they ate. Further questions are asked about the plant fossils found in the rocks and what the rocks themselves say about the environment. Was it a desert? A beach? Shallow marine? Once they have what is known, then they can fill in what is not known. The next few pages provide a short history of dinosaur science and the art that sprung from it, such as the early Waterhouse Hawkins Crystal Palace sculptures in London during the 1850s and the Charles Knight paintings adorning the American Museum of Natural History. The book continues with information gleaned from trackways and new technologies helping to spur more discoveries. A discussion of the skeletons leads into reconstructing soft tissues such as muscle and eyes over the bones.
One area in which views have changed significantly is in the skin, which is discussed next. The book describes how new fossils are helping to inform new views, such as feathered raptors, although the book does not mention that we even have evidence of feathers on tyrannosaurs now. This is one area in which the book could have gone farther, it did not discuss much of the diversity of feathers, quills, and assorted spines we have recently found on a variety of dinosaurs. The use of modern animals and analogs and mechanical constraints, such as skin around joints, is also discussed. The problems and possibilities of how one decides on a color is discussed, ending on a mention of new fossils that are beginning to give us amazing insight into actual colors of some dinosaurs.
Yutyrannus, by Brian Choo via nature. 2012. Not in book.
The information here is not presented as definite conclusions, but as a puzzle, in which the scientists and artists take the various clues and try to piece them together. Sometimes, mistakes are made, such as the thumb spike of Iguanodon was originally thought to be a nose horn. The descriptions demonstrate how vibrant and dynamic the work is. As new fossils and new information comes to light, views change accordingly. The workers must constantly adapt as their knowledge base grows, with each new find getting us closer to a more accurate understanding.
The one quibble I would make with the book is one which Switek also mentioned. The book begins by stating that no one has ever seen a real, live dinosaur, which is not true. We see them every day. They are in fact the most diverse group of vertebrate animals outside of fish. The book mentions that dinosaurs and birds are thought to be related. In fact, it is often said that birds are dinosaurs because birds evolved from earlier dinosaurs. So just like children are still in the same family as their parents, birds are in the same family as all the other dinosaurs. This relationship is a key point in reconstructing fossil dinosaurs. Of course, a lot of people find it bothersome to constantly have to refer to non-avian dinosaurs to refer to only those that lived during the Mesozoic, so it is justifiable to say dinosaurs and birds, so long as it is made clear at the beginning that dinosaurs in that context are only referring to the Mesozoic ones. this book doesn’t do that, which is the only big gripe about the book. Still, a relatively minor complaint compared to the rest of the book, which is done wonderfully.
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