Introducing the Dental Microwear Image Library

Dental microwear, seen in the tiny pits and scratches on a tooth, provides lots of detailed data for inferring diet and chewing behavior in animals. Analyses are often conducted by digitizing highly magnified images of the tooth surface and counting up and classifying the various microscopic features. Animals with a certain percentage of pits and scratches may have browsing habits, whereas those with another profile may be grazers. By measuring extant animals with known diet, we can (hopefully) infer the diet of extinct animals.

Dental microwear; modified from figure 3 in Mihlbachler et al., 2012

In this age of increasingly open science, microwear studies can be problematic. A cornerstone of science is reproducibility - yet, inter-observer variation and error can greatly affect measured data. Furthermore, one study alone may generate dozens or hundreds of images. Even if you wanted to re-analyze teeth, it's pretty tough - how could you get access to the necessary images? Ideally, we want a world where anyone can access the raw image data, make their own observations, double-check published analyses, and add new data for comparison.

Thus, a new project - called the Dental Microwear Image Library, or DMIL - may change things. Assembled by Brian Lee Beatty and Matthew Mihlbachler, the website aims to become a clearinghouse for dental microwear images. This will allow greater standardization of analyses and hopefully better interpretations of paleoecology and diet for extinct organisms and modern organisms. The first data (from a recent paper in Paleontologia Electronica) are now posted, along with many other data sets.

Brian Lee Beatty (who blogs at The Aquatic Amniote and tweets as @Vanderhoofius) was kind enough to answer a few questions about the DMIL. Thanks, Brian!

Was there a particular moment or incident that inspired you to build the DMIL? If so, what was it?
As we set out to test and develop the method that Nikos Solounias and Gina Semprebon started, we found ourselves frustrated by not only the lack of information on methods that were given in most microwear papers, but also the inability for people to check their work. Interobserver error is a major cause of problems for microwear, and the only way for anyone to be aware of those differences is if they compare interpretations of microwear surfaces, not just their numbers on a spreadsheet. The DMIL was the only possible solution to the need to share such images.

How has community response been so far? Is there any particular type of skepticism that you're working to overcome?
The DMIL hasn't yet come up against skepticism, but our first paper on this method that uses it has.

What license, if any, are the data housed under? Or is it on a case-by-case basis?
There is no license for the data. We want it to be completely open-access and simply available.

How would you envision the DMIL 10 years from now? What goals might you have for the long-term?
We hope it will be a place that people can use to learn how to use the methods we are continuing to develop. I most sincerely hope that it will not only be home to our own data, but also be a place for others to deposit their data using similar methods so that more work of this sort is available in a similar, comparable format.

Authors of the recent paper in PE, along with a research assistant. Photos courtesy of Brian Lee Beatty.

For more information, check out the DMIL, or read the recent paper (open access) about the work.

Citation:
Mihlbachler, Matthew C., Beatty, Brian L., Caldera-Siu, Angela, Chan, Doris, and Lee, Richard, 2012. Error rates and observer bias in dental microwear analysis using light microscopy. Palaeontologia Electronica Vol. 15, Issue 1;12A,22p.

Restoring that sense of wonder

These can be depressing times for a paleontologist - funding is poor for most, the job market is dim for many talented friends and colleagues, and rhetoric-ridden battles for scholarly publishing rage. That's enough to suck the joy right out of the field. In instances like this, it's nice to step back for a second and think about the really cool stuff going on.

So, I've put together a list of wondrous things that have happened in paleontology over the past several years. Why are they cool to me? Mostly because they challenge ideas that I acquired while a little, dinosaur-obsessed kid. And they also challenge ideas I've acquired as an "educated" professional. Sometimes it's nice to have our comfort zone stretched.

Symbols of the new paleontological revolution: an eye-catching Sinosauropteryx crouches on top of mammoth DNA, overlain on a thin-section of dinosaur bone (sources at end)

In no particular order:

• We know what colors were on parts of the body of some dinosaurs. Really. How cool is that? Sure, it's not perfect, and there is lots we'll never know, but the mere fact that you can plausibly reconstruct parts of the pelage of a feathered dinosaur is amazing. Especially because I had always believed the truism that we'd know the texture of dinosaur skins, but never the color.
• I can download a genetic sequence from a woolly mammoth. Or a Neanderthal. Or any number of extinct organisms. I had always known that Jurassic Park would never be a reality. It probably never will be (at least for non-avian dinosaurs). But to stare at the A's, T's, G's, and C's of an extinct organism still gives me some goosebumps.
• I can listen to a Jurassic katydid. Yes, yes, there are some assumptions in the reconstruction. But let's suspend criticism for a moment, and accept that it's probably at least a decent approximation. These are noises that haven't been heard in 165 million years.
• We know the sex of some individual dinosaur specimens. Thanks to studies of medullary bone and comparative anatomy, the seemingly impossible is made real. Wow!
• Similarly, we know the age of some dinosaur individuals at death (give or take a few years). The notion that sauropods only got big because they grew for a century can't be supported anymore. Once again - wow!

This is just my personal list - what's on yours?

Sources for image: Mammoth DNA sequence in background from GenBank Accession FJ655900 (published by Enk et al., 2009); dinosaur bone histological section modified from Woodward et al. 2011 Figure 1C (colors inverted and adjusted); Sinosauropteryx modified from original by Marty Martunuik. Image released under Creative Commons Attribution-Share Alike 3.0 Unported license.

The Curse of the Nonexistent Dinosaurs

You all probably remember Darwinius, that little extinct primate that caused such a huge fuss last year (the image at left is from the original paper). In addition to the massive hyperbole surrounding the specimen (much of which has now been tempered by additional analyses from other researchers), an early issue concerned the validity of the name Darwinius itself.

Scientific names for new animals, living or extinct, are governed by a set of rules from the International Commission on Zoological Nomenclature (ICZN). This body - which has no real authority, other than that granted it by us scientists - is by its nature a rather conservative entity. This isn't necessarily a bad thing, particularly because stability in our naming system is so critically important. When I say Kosmoceratops richardsoni, everyone else should know I'm talking about. But, this conservatism also means that the ICZN has been very, very slow to react to electronic publishing. Right now, names published in electronic-only form are not valid! A paper version, even if it is otherwise identical to the electronic version, must be created (although the ICZN is working to change this).

So back to Darwinius. . .when the name was initially published, it was only in electronic form, and thus not "real" in the eyes of the ICZN. Vigilant eyes noted this, and the problem was rapidly broadcast in the blogosphere. Some wags suggested naming Darwinius out from under the authors, but thankfully cooler heads prevailed. PLoS ONE, the journal in which Darwinius was published, was able to produce a paper copy of the article in order to satisfy the ICZN. It took a few days, but finally Darwinius was "real"!

Thankfully, PLoS ONE learned its lesson. Their publication policies (full disclosure: I am an editor there) have been revised to accommodate the needs of the ICZN, and all is happy now. Or is it?

It turns out that other journals haven't necessarily learned this tough lesson. Time and again, scientific names invalid in the eyes of the ICZN are being published by some pretty major journals. This "zombie nomenclature" walks among us, even today. Here are just two examples.

Raptorex (image by Nobu Tamura)

On September 17, 2009, Science posted a preprint of a paper naming a new small tyrannosaur, Raptorex kriegsteini. As near as I can tell, this name existed only in electronic form at the time, and thus was not yet valid in the eyes of the ICZN. Raptorex was very well publicized (and rightfully so - it's a neat specimen), yet no paper edition appeared until October 16, 2009 - a month later. For four weeks, the name Raptorex was in taxonomic limbo.

Koreaceratops (image by Nobu Tamura)

This early horned dinosaur is hot off the digital presses. As you can probably guess, it hails from South Korea, and the authors hypothesize that it may have been aquatic. Koreaceratops appeared on November 17, 2010, as an online preprint at Naturwissenschaften, and some media attention started popping up earlier this week. Yet. . .the name is not yet valid in the eyes of the ICZN! Until Koreaceratops appears on the printed pages of that journal, the name has no real weight. Hopefully this will get resolved soon!

Cryptovenator (image by Charles R. Knight)

Dinosaurs (and Darwinius) aren't the only organisms afflicted by digital naming issues. On September 16, 2010, the genus Cryptovenator appeared on the website for Acta Palaeontologica Polonica, as a new kind of early synapsid (closely related to the fin-backed Dimetrodon, depicted at right). It hasn't yet appeared in print - so remains "undead" according to the ICZN.

Some Thoughts

The rise of online pre-prints is a Good Thing. It speeds the flow of scientific information in a way that just wasn't possible before. Yet, it also creates a bit of a headache for authors. The window of time between pre-printing and real-printing is a dangerous place for a new scientific name. Although the threat is slight, there is nothing to stop someone from accidentally or intentionally "scooping" the rightful authors. As near as I can tell, the proposed ICZN rules won't do anything to fix the situation, either.

So, what solutions are there?

1. Don't publish pre-prints of papers with nomenclatural acts. This is the simplest solution in some ways, but also produces the undesirable effect of slowing down scientific communication. Canadian Journal of Earth Sciences has adopted this strategy (hat-tip to Hans-Dieter Sues for the reminder on this one).
2. Petition the ICZN to give priority to the first appearance of the name in the first widely disseminated pre-print of a paper. This would be a nightmare on multiple levels - an addendum to the Code could take years, and how would one decide which version of a paper containing a name is the authoritative one?
3. Continue to publish pre-prints, assume that all is going to be well, and worry about it when something bad happens (taxonomic scooping, perhaps?). Highly undesirable, but basically the course of action that we're on now.
4. Expunge the names from the paper in its pre-print form (suggested by Martin Brazeau at another venue). This does solve the problem, but it requires someone to go through the paper and remove all mentions of the taxon. Despite all of the talk from commercial publishers about "value added", I suspect it's either the unpaid editorial volunteers or unpaid authors who would get stuck doing this. Removing names is not so tough in the text, but figures (such as phylogenies) would be a bear. Also, we're left with multiple versions of the same paper floating around.

What thoughts do you have on the matter? Is it really an issue? Or am I making a mountain out of a molehill? Speak up in the comments section!

Disclaimer: Mention of the "invalid" names above is not, not, not an invitation for paleontological wannabes, ethical miscreants, or rabblerousers to wreak havoc on paleontological nomenclature. Although I hesitate to draw attention to particular instances, I feel that without some concrete examples, my arguments would be less effective. Furthermore, the names are already out there in some very widely read venues! Leave the names for the authors; the situation is not their fault.

Update December 31 2010: Bill Parker over at Chinleana has a great post relevant to this issue.

A Flood of Paleo Articles in PLoS ONE

It has been pretty incredible to see the rise of PLoS ONE as a major outlet for articles on paleontology, and it has been equally incredible to ride along as an editor for that journal. The past few months have seen many scientifically important and interesting papers wend their way into publication. I haven't had a lot of time for blogging lately, but wanted to take this opportunity to highlight the latest paleo-themed research in PLoS ONE. The following list is in reverse chronological order (newest to oldest), covering work published in the last three months.

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Slater GJ, Figueirido B, Louis L, Yang P, Van Valkenburgh B (2010) Biomechanical Consequences of Rapid Evolution in the Polar Bear Lineage. PLoS ONE 5(11): e13870. doi:10.1371/journal.pone.0013870
Summary: The authors present and interpret finite element modeling results for polar bears and brown bears, showing that the skulls of polar bears are generally weaker than those of their close cousins. Furthermore, these differences probably accumulated rather rapidly.

Xu X, Wang K, Zhao X, Sullivan C, Chen S (2010) A New Leptoceratopsid (Ornithischia: Ceratopsia) from the Upper Cretaceous of Shandong, China and Its Implications for Neoceratopsian Evolution. PLoS ONE 5(11): e13835. doi:10.1371/journal.pone.0013835
Summary: Zhuchengceratops inexpectus is introduced; this small horned dinosaur is actually among the largest of its kind, the "leptoceratopsids." Interestingly, it showed up in a big bonebed in eastern China, along with truly giant horned dinosaurs and duck-billed dinosaurs.

Longrich NR, Horner JR, Erickson GM, Currie PJ (2010) Cannibalism in Tyrannosaurus rex. PLoS ONE 5(10): e13419. doi:10.1371/journal.pone.0013419
Summary: Bones of Tyrannosaurus with T. rex tooth marks are described; the implications are pretty self-evident (see the title of the paper, if you're still trying to figure this out). This paper received considerable media attention; Brian Switek has one nice write-up at Dinosaur Tracking.

Cisneros JC, Gomes Cabral U, de Beer F, Damiani R, Costa Fortier D (2010) Spondarthritis in the Triassic. PLoS ONE 5(10): e13425. doi:10.1371/journal.pone.0013425
Summary: Suffering from what is described as the earliest known example of arthritis, an early archosaur had a pretty rough time with some fused vertebrae. Diagnoses of disease in fossil organisms can be pretty controversial; I shall be interested to see how this particular case study plays out.

Smith ND (2010) Phylogenetic Analysis of Pelecaniformes (Aves) Based on Osteological Data: Implications for Waterbird Phylogeny and Fossil Calibration Studies. PLoS ONE 5(10): e13354. doi:10.1371/journal.pone.0013354
Summary: Here, the relationships of pelecaniform birds (including pelicans, cormorants, boobies, and more) is addressed in great detail. The group is not found to be monophyletic, and the unstable nature of the position of several key taxa means that ornithologists will be talking about this question for some time.

Han J, Kubota S, Uchida H-o, Stanley GD Jr, Yao X, et al. (2010) Tiny Sea Anemone from the Lower Cambrian of China. PLoS ONE 5(10): e13276. doi:10.1371/journal.pone.0013276
Summary: What the title says. The authors suggest that their new animal, called Eolympia pediculata, is a stem member of the group including corals and sea anemones. The image at right shows the authors' reconstruction of Eolympia.

Peterson JE, Lenczewski ME, Scherer RP (2010) Influence of Microbial Biofilms on the Preservation of Primary Soft Tissue in Fossil and Extant Archosaurs. PLoS ONE 5(10): e13334. doi:10.1371/journal.pone.0013334
Summary: This article presents experimental support for the idea that microbial biofilms form a protective layer that allows preservation of deeper soft tissue structures in dinosaur bones and other fossils-to-be. Read more about the research here. Interestingly, the article by Peterson et al. disagrees with an earlier paper published in PLoS ONE (written by Kaye et al.), stating that any alleged soft tissue preserved in fossils is a microbial film alone. Thus, the bacterial biofilms exist - but they're not the only biogenic structure in these bones!

Holliday CM, Ridgely RC, Sedlmayr JC, Witmer LM (2010) Cartilaginous Epiphyses in Extant Archosaurs and Their Implications for Reconstructing Limb Function in Dinosaurs. PLoS ONE 5(9): e13120. doi:10.1371/journal.pone.0013120
Summary: Things aren't as they appear; the big dinosaur bones that we see in museums today were probably much longer in life, supplemented by giant cartilaginous caps. Lead author Casey Holliday presents more information here, and Mike Taylor at SV-POW also has stuff to say about the topic.

Oxnard C, Obendorf PJ, Kefford BJ (2010) Post-Cranial Skeletons of Hypothyroid Cretins Show a Similar Anatomical Mosaic as Homo floresiensis. PLoS ONE 5(9): e13018. doi:10.1371/journal.pone.0013018
Summary: Yet another round in the discussion about the "hobbits" of Flores, Indonesia. I get the sense that Oxnard et al. are very much in the minority opinion, but I also get the sense that this debate is going to drag on for awhile more.

Rando JC, Alcover JA, Illera JC (2010) Disentangling Ancient Interactions: A New Extinct Passerine Provides Insights on Character Displacement among Extinct and Extant Island Finches. PLoS ONE 5(9): e12956. doi:10.1371/journal.pone.0012956
Summary: A recently extinct finch, Carduelis aurelioi, is named and compared with its fellow prehistoric finches (some of which are still alive today). Evidence is presented to suggest that the effects of ancient competition between the species still reverberate today. The image at left shows a life restoration of the new species, as imagined by A. Bonner.

O'Rourke CT, Hall MI, Pitlik T, Fernández-Juricic E (2010) Hawk Eyes I: Diurnal Raptors Differ in Visual Fields and Degree of Eye Movement. PLoS ONE 5(9): e12802. doi:10.1371/journal.pone.0012802
Summary: It's not strictly paleontology, but the methods here present actual experimental validation of the true visual fields for extant birds of prey. It would be interesting to compare the visual fields as calculated from the osteology alone with the experimental results - and then see what this means for similar calculations performed for extinct dinosaurs.

Sampson SD, Loewen MA, Farke AA, Roberts EM, Forster CA, et al. (2010) New Horned Dinosaurs from Utah Provide Evidence for Intracontinental Dinosaur Endemism. PLoS ONE 5(9): e12292. doi:10.1371/journal.pone.0012292
Summary: Utahceratops gettyi and Kosmoceratops richardsoni, two new horned dinosaurs, are named, and their implications for Late Cretaceous biogeography in North America are discussed. This paper, on which I was a co-author, received a substantial amount of media attention. See my blog post on the subject as a starting point for more information.

Kraatz BP, Meng J, Weksler M, Li C (2010) Evolutionary Patterns in the Dentition of Duplicidentata (Mammalia) and a Novel Trend in the Molarization of Premolars. PLoS ONE 5(9): e12838. doi:10.1371/journal.pone.0012838
Summary: Here, the authors propose new ways to interpret the anatomy and evolution of rabbit teeth, based on some previously undescribed fossils.

Noto CR, Grossman A (2010) Broad-Scale Patterns of Late Jurassic Dinosaur Paleoecology. PLoS ONE 5(9): e12553. doi:10.1371/journal.pone.0012553
Summary: The Jurassic was an age of giants. The structure of some old, old ecosystems is reconstructed by classifying and comparing the ecomorphotypes of a number of dinosaurs from this time.

Degrange FJ, Tambussi CP, Moreno K, Witmer LM, Wroe S (2010) Mechanical Analysis of Feeding Behavior in the Extinct “Terror Bird” Andalgalornis steulleti (Gruiformes: Phorusrhacidae). PLoS ONE 5(8): e11856. doi:10.1371/journal.pone.0011856
Summary: Terror birds are pretty much what the name says - imagine something the size of "Big Bird" from Sesame Street, preying on Mr. Snuffleupagus. This article, which also received broad media coverage (see the Witmer Lab blog as a starting point), finds that the skulls of these big birds were quite strong in the up-and-down direction, but not so strong from side-to-side.

Lindgren J, Caldwell MW, Konishi T, Chiappe LM (2010) Convergent Evolution in Aquatic Tetrapods: Insights from an Exceptional Fossil Mosasaur. PLoS ONE 5(8): e11998. doi:10.1371/journal.pone.0011998
Summary: A spectacularly-preserved ancient sea reptile shows skin impressions, bronchial tubes, possible skin coloration, and even potential traces of some internal organs. Feathered dinosaurs may get all of the attention, but the specimen described here rivals them in "wow" factor!

Image from Lindgren et al. 2010

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Some parting thoughts:

• In my (biased) opinion, most of these papers are presenting some pretty solid science (or at the very least, stimulating science). Now that PLoS ONE has an impact factor (and thus presumably more people interested in submitting to the journal), I hope that the quality of the submitted work is maintained.
• There is a pretty major skew towards papers on vertebrates - 15 out of 16 (94 percent) of those mentioned above primarily concern things with backbones . Six out of the 16 papers mentioned above (38 percent) are about non-avian dinosaurs. Let's get some more variety, folks!
• Some interesting work on functional morphology and other aspects of evolutionary biology (only a handful of which are sampled above) has been appearing lately. I strongly recommend subscribing to content alerts (start the process here) or regularly browsing the journal's website, in order to keep up on the latest and greatest work that might be relevant to you.
  
• I look forward to more stimulating papers appearing in the near future. And if you haven't submitted something to PLoS ONE yet, please consider doing so!

Full disclosure: I am a section editor at PLoS ONE.

Cool New Paleo Project

Darren Tanke, a technician at the Royal Tyrrell Museum of Paleontology, is probably one of the most knowledgeable people around when it comes to the history of paleontology in Alberta. I've known Darren for a number of years (and have co-authored several papers with him, including this one), and his enthusiasm for paleo lore is quite infectious. Stick around him for an hour or two, and you'll learn about the clues contained within quarry trash. . .discarded newspapers, plaster bits, sardine tins, and bottles are invaluable for identifying the original excavators of otherwise anonymous quarries. Many early paleontologists only kept the most minimal documentation, but thanks to Darren and his colleagues we now know the exact stratigraphic position for many important specimens from Dinosaur Provincial Park. This unglamorous service, a meld of archaeology, history, and paleontology, has done wonders for clarifying our understanding of Cretaceous ecosystems.

In the old days, vehicle access to places like Dinosaur Provincial Park was pretty darned difficult. In fact, many of the first expeditions were by boat, floating down the Red Deer River. Life is much easier for fossil collectors now. . .but in honor of these early expeditions, Darren is going to collect by boat once again! The Tyrrell's master carpenter, Perry Schopff, is presently working to recreate one of the AMNH's original scows. And come next summer, Darren and his crew of paleontologists will float in the footsteps of legends such as Barnum Brown - exactly 100 years after the first floating expedition.

In the spirit of open science, Darren and friends have put together a blog and Facebook group (search for "Dinosaur Hunting by Boat in Alberta, Canada") with all of the latest photos and updates. Here's to open science, and a successful field season in 2010!

Blogroll Updated

I just updated my blogroll, and have added a few new paleo-relevant links. In particular, I'd like to call attention to Jeffrey Martz's "Paleo Errata." The first few postings are very much in the spirit of my own blog, and offer some excellent advice to those hapless folks considering a career in paleontology. Go check it out!

Book Review: Microvertebrate Fossil Assemblages

Microvertebrate Fossil Assemblages: Their Role in Paleobiology and Paleobiogeography, edited by Julia T. Sankey and Sven Baszio (Indiana University Press, 2008)

Indiana University Press’s Life of the Past series has unleashed a wealth of scientific and popular books on various aspects of paleontology. The latest offering, Microvertebrate Fossil Assemblages: Their Role in Paleobiology and Paleobiogeography, continues this fine tradition. The editors, Julia Sankey and Sven Baszio, are no strangers to the world of microvertebrate fossils (those tiny teeth, vertebrae, scales and other bones from fish, reptiles, non-avian dinosaurs, birds, and amphibians), having published many papers of their own focusing on microvertebrate assemblages from the Late Cretaceous of North America. Here, the editors have brought together a fine collection of papers primarily addressing this very topic. The general nature of the volume’s title does not entirely accurately reflect the papers within, however – the vast majority of the 13 chapters focus on continental microvertebrates from the Cretaceous of western North America. It may disappoint workers of Cenozoic or Paleozoic strata, or those who study marine facies, to see such small notice given to non-Cretaceous, non-terrestrial deposits. Despite this debatable “shortcoming,” there is much to admire here.

The first chapter, by Sven Baszio, lays out potentials and pitfalls of microvertebrate assemblages for answering a variety of questions. Clearly, much progress has been made in this front since the first major screenwashing efforts of the 1960s. A second chapter, by Jamniczky et al., addresses a method for estimating the sufficiency of a sample for characterizing a microsite. Such statistical rigor is clearly needed. Schiebout et al.’s contribution represents the only section of the entire volume that does not dwell largely in the Mesozoic – here, the authors document associations of Cenozoic-aged mammalian fossils within pedogenic concretions.

The next three chapters address microvertebrate assemblages and their role in paleoecological reconstruction. Brinkman examines the role of microvertebrates in reconstructing guild structure within the Dinosaur Park Formation of Alberta, Canada. He pays particular attention to the role that taphonomy plays in how we reconstruct extinct ecosystems. Chapters by Sankey and DeMar and Breithaupt report on assemblages from the Aguja Formation of Texas and the Mesaverde Group of Wyoming, respectively.

A chapter by Fiorillo represents the only paper focused primarily on functional morphology. Here, Fiorillo uses microwear to examine potential variation in diet within sauropods from the Morrison Formation. Somewhat surprisingly, he reports that microwear patterns did not vary within taxa (regardless of where they lived), suggesting uniform diets. Unfortunately, no statistics are presented to validate this conclusion. This is a minor point, but a nagging one for my brain, which thrives on the “numbers game”!

The remaining chapters are largely systematic in nature. Sankey and Longrich each have their own chapter addressing theropod teeth from the Lance and Hell Creek Formations. Sankey provides a particularly useful table of measurements, and both chapters are well-illustrated. Apparently, the two authors come to somewhat different conclusions on systematics of isolated theropod teeth. In particular, Longrich floats the hypothesis that teeth referred to Richardoestesia (R. isosceles and R. gilmorei) all come from the same animal known as Paronychodon! This thus implies a heterodont dentition. Many of the small theropod taxa from the Lance and Hell Creek Formations are known only from teeth – it will take some well-preserved jaw material to sort out the true identity of most of these morphotaxa.

Currie and Coy report on a bird tooth from the Belly River Group; this tooth is particularly unusual for its serrated morphology. Welsh and Sankey then describe numerous types of eggshell from the Aguja Formation of Texas – clearly, a wide variety of dinosaur taxa were nesting in this area!

The final two chapters of the book, by Gardner and Böhme, and Gardner, focus on the less “glamorous” side of microvertebrate fauna: amphibians. Despite the fact that amphibians don’t have the cachet usually afforded dinosaurs, the chapters in question are important for clarifying the systematics and taxonomy of these groups. The numerous photographs in Gardner’s contribution on frogs will be very useful for those of us who have struggled with identifying frog material in the past.

Now, on to the “nuts and bolts” of the book itself. The hardcover volume is a convenient size and attractively jacketed, as is typical of the IUP series. The dust jacket art, by Russell Hawley with coloration by Nick Longrich, presents a dynamic reconstruction of many of the animals revealed in Cretaceous vertebrate microassemblages. In terms of the chapters themselves, the editors did a remarkably fine job of proofing the manuscripts, and typos are scarce (not always the case in some recent IUP volumes). One minor annoyance is the fact that none of the chapters have an abstract or summary at the beginning (and many don’t even have a summary at the end!). This makes it somewhat difficult for the casual reader to determine quickly the overall gist of an individual contribution. The illustrations are generally very well-reproduced, with good contrast and clarity. The book itself has a list price similar to comparable volumes ($59.95), but a quick search on Amazon (or a trip to the SVP meetings) will find some decent discounts.

My initial reaction to the papers in this book is that there is still a long way to go in understanding even the best-studied microfaunas of North America. Gardner’s chapter on frogs, and Sankey and Longrich’s chapters on theropods, particularly highlight this point. The taxonomy and systematics of these clades, even within the heavily-sampled Bug Creek fauna, or the Belly River Group fauna, is not yet settled in some cases. This should give heart to those of us early in our careers! And, the “guild analysis” presented by Brinkman also may point the way to other future studies. Finally, it never hurts to have more samples, focusing on different horizons and collecting methodologies.

So, who should buy this volume? I would say that anyone working in the Late Cretaceous of North America would do well to purchase a copy, as would those who work on some of the taxa detailed within (small theropods, frogs, etc.). Kudos to the editors and authors on this interesting contribution!