Grad Publications: David DeMar, Jonathan Calede, Daril Vilhena, Elisha Harris, Max Maliska, & Adam Huttenlocker -- An eruption of UW paleobiology!

Let this week be known as the week of UW paleobiology in the literature! It should be noted that these papers were either single author publications or the grad was the primary author.

An extant mudpuppy.

      David DeMar described a new genus and species of salamander from the end of the Mesozoic in the Journal of Vertebrate Paleontology.
      Dave: Paranecturus garbanii is a new genus and species of fossil salamander from the latest Cretaceous of Montana and is closely related to the modern day mudpuppy of the family Proteidae. P. garbanii is the oldest and only species of proteid salamander known to live prior to the Cretaceous-Paleogene boundary (~66 million years ago) thus implying that proteid salamanders survived the end Cretaceous mass extinction event.
Here is Dave's paper.

A helical Palaeocastor burrow with the poor
burrower preserved at the end.

      Jonathan Calede's paper in the Journal of Mammalian Evolution looks at ontogenetic changes in a burrowing beaver and is based on his term paper for Greg Wilson's mammal evolution class.

      Jonathan: This project was actually initiated as my term project for BIOL 443. It is the first description of palaeocastorine beavers (an extinct subfamily of burrowing beavers) from the Fort Logan Formation of Montana (~28 million years old, Meagher County). I found that there were at least three species of these beavers including one previously only known from the John Day Formation of Oregon: Palaeocastor peninsulatus. 

      This species is represented by three skulls and associated partial skeletons forming an ontogenetic series from a juvenile to a mature adult. The analysis of these specimens shows that morphological changes throughout ontogeny are associated with increased burrowing ability in adults. It appears that the the changes in burrowing behavior between juveniles and adults mirrors changes observed throughout the evolution of palaeocastorines.

      Daril Vilhena (back again!), Elisha Harris, and Max Maliska authored a collaborative paper dealing with extinction selectivity among bivalves at the end Cretaceous mass extinction event in Scientific Reports.

The world's continents as they were at the end of the Mesozoic Era
66,000,000 years ago. Map by Ron Blakey.

      Daril: The Cretaceous-Paleogene (K/Pg) extinction event has remarkably equal extinction rates across the globe for marine bivalves, which are arguably the best preserved clade for that time interval. This is surprising considering that proposed mechanisms for extinction vary considerably geographically (volcanism, asteroid, dust cloud versus heat pulse, etc). However, we grouped bivalves by their biogeography, and found that regions at lower latitudes had higher extinction than expected given the geographic ranges of the bivalves. This suggests that i) the mechanism for extinction declined in intensity towards the poles, ii) tropical lineages were more vulnerable to extinction, or iii) both.

Adam's ON FIRE!!!!!!!!!!!!!!

      Last, but not least, Adam Huttenlocker returns for his unprecedented, third consecutive appearance on SciPos. That's right ladies and gentlemen, three pubs in as many weeks. This week Adam's paper describes two new genera of burrowing amphibians from nearly 300 million years ago (sort of a weird combo of Dave and Jonathan's papers?). One of the new genera has been dubbed Huskerpeton in honor of its Nebraska 'corn-husker' provenance and (unofficially) the University of Washington huskies. 

      Adam: Recumbirostran microsaurs were small amphibians with elongate bodies and pointed shovel-like snouts, and are best known from late Early Permian redbeds in the southwestern US in which they often co-occur with lungfish in estivation assemblages. They superficially resemble modern caecilians, and have at times been suggested to share a close relationship with caecilians and salamanders. The paper describes two new genera of morphologically conservative recumbirostrans from the earliest Permian of Kansas and Nebraska. The new taxa share a close relationship to some lesser understood forms from Germany, sharing a similar degree of morphological conservatism. We suggest that the diverse forms of burrowing recumbirostrans that radiated during the Early Permian were already biogeographically widespread by the Carboniferous-Permian transition (~300 million years ago), but are poorly sampled in the fossil record due to the relative conservatism and small body sizes of early forms.

A recombirostran microsaur amphibian from the Permian.

~Brandon

Grad Publication: Daril Vilhena, Adam Huttenlocker, Brandon Peecook

      What happens when one group of scientists accumulate a bunch of data, but don't quite know the best way to ask their questions, work in the same integrative department as a pioneering mathematical biologist with new methods, but no dataset?

C.O.L.L.A.B.O.R.A.T.I.O.N.

      Over the last few years the Sidor lab has been criss-crossing southern continents (formerly a part of Gondwana 250,000,000 years ago) collecting vertebrate fossils from areas that had not been very well studied. These fossils, including several exciting new species, are from rocks on either side of the largest mass extinction event of all time, the end-Permian extinction event (~252.3 million years ago). Differences between the pre- and post extinction worlds were qualitatively obvious to us paleontologists and included a turnover of species, the rise of new clades, and changes in the biogeographic characteristics of assemblages.
      Last year Daril Vilhena, of the Bergstrom lab, and Chris Sidor began discussing a new method of biogeographic analysis that Daril was developing that used network theory. After much back and forth, including meetings with other paleo faculty, it became apparent that turning the biogeographic occurrences of different taxa in different places across different times into a network would be a valuable metric of biogeographic change.

Newly discovered fossils, and those from existing collections, were considered from five basins in the south of what was once a single large land mass known as Pangea, and today are part of (from left to right) South Africa, Zambia, Malawi, Tanzania and Antarctica.

      This week our work was published in PNAS and received excellent coverage in the media. Please check the links below for a more specific and engaging summary of our research.

Science
Science Daily
UW Today

And here's the paper!

~Brandon

Grad Publication: Adam Huttenlocker -- Bigger not always better in a post-extinction world?

Adam's paper: Huttenlocker, A. K., and J. Botha-Brink. 2013. Body size and growth patterns in the therocephalian Moschorhinus (Therapsida) before and after the end-Permian extinction in South Africa. Paleobiology. 39:253-277. doi: http://dx.doi.org/10.1666/12020

        The K-Pg extinction, responsible for the catastrophic ecosystem collapse that blotted out the non-avian dinosaurs some 65 million years ago, is ostensibly the best-known extinction event in the entire history of Earth. But surprisingly few people are aware of an even greater event that disrupted links in communities on land and in the oceans during the Earth’s last major icehouse-hothouse transition about 252 million years ago: the end-Permian extinction. This event shared many characteristics with the K-Pg extinction, but with a much higher death toll, wiping-out nearly 90% of animal species. It is estimated that animal communities did not return to their former ecological diversity until some eight million years later, during the Middle Triassic.

Huge gorgonopsians and their prey went extinct at the close of the Permian Period (ca. 252 million years ago). (artwork: Dmitry Bogdanov)

        The identification of common themes between extinctions (and across marine and non-marine environments) has endowed historical biologists with predictive tools as the world faces new ecological challenges. Scientists who study mass extinctions are in a unique position to determine common patterns of degradation and collapse, reconstructing the progression of an extinction, identifying its parts and phases (e.g., initial extinction, survival, and recovery phases) and the underlying characteristics of each phase. With respect to these phases, paleontologists have become increasingly interested in the common historical and biological factors that influence recoveries, allowing some groups to flourish and take hold of new ecological opportunities in a post-extinction world.

        Several of the Big Five extinctions are characterized not only by reductions in species numbers and abundance, but also by the small body sizes of putative disaster taxa—the Lilliput phenomenon (which pulls its name from the tiny inhabitants of the island of Lilliput in Jonathan Swift’s classic Gulliver’s Travels). Terms like ‘Lilliput taxa,’ ‘Lazarus taxa,’ ‘Elvis taxa,’ and ‘dead clade walking’ are just a few of a grocery list of idioms that researchers have invented to describe specific attributes of survivor and recovery taxa. Unfortunately, the underlying mechanisms producing species that fit these monickers may not always be as easy to identify. For example, temporary body size reductions in Lilliput taxa could result from a size-selective extinction in which pre-existing large-bodied species became extinct (leaving only small survivor taxa), but could also arise from within-lineage size decreases (e.g., heterochronic processes acting within survivor lineages). Consequently, growth data from species within clades that survived major extinctions (such as the end-Permian extinction) are now providing insights into the influences of Lilliputian patterns following extinction events.

        Temporary post-extinction body size reductions have been well-documented in many marine invertebrate groups following the end-Permian extinction, including gastropods, conodonts, foraminifera, and brachiopods. Recent work on Early Triassic brachiopod shells from northern Italy suggests that not only did miniaturized versions of pre-extinction taxa persist in the disaster fauna, they achieved their unusually small sizes by slowing down their overall skeletal growth rates (inferred by counting and measuring tiny annual growth rings recorded in the shell of the animal—a technique called ‘sclerochronology’).

Some terrestrial vertebrates (like this carnivorous Moschorhinus) survived the end-Permian extinction, but were noticeably smaller in the post-extinction survivor fauna. Upper left: Moschorhinus from the Permian Dicynodon Assemblage Zone; middle: Moschorhinus from the Triassic Lystrosaurus Assemblage Zone; lower right: Olivierosuchus, a smaller cousin of Moschorhinus, also from the Triassic.

        In spite of these developments in invertebrate paleontology, there has been a lag in studies of terrestrial vertebrate growth and life history patterns in the aftermath of extinctions. In an article published this month in Paleobiology, my coauthor, Jennifer Botha-Brink, and I identify differences in body size and growth patterns in a single vertebrate genus from the Permo-Triassic boundary of the Karoo Basin of South Africa: Moschorhinus kitchingi, an extinct forerunner of mammals or ‘therapsid.’ We collected body size data in stratigraphically successive populations of Moschorhinus and histologically thin-sectioned limb bones to study their microstructure as a means of understanding changes in skeletal growth. The study partly corroborates recent observations on body size reductions in earliest Triassic marine invertebrates, but provides additional life history data indicating that observed size variation over geologic time is owed largely to differential juvenile growth rates and growth duration. Interestingly, Triassic Moschorhinus (and perhaps other Karoo vertebrates) did not exhibit slower growth rates like the Italian brachiopods, but instead displayed fast, relatively sustained growth over fewer growing seasons. Our work suggests the possibility that Lilliputian phenomena in marine and non-marine taxa were influenced by different processes. Differences in marine and non-marine biotic responses underscore the need to study the phylogenetic and life history components of Lilliputian phenomena, improving our ability to address causality during mass extinctions. 

--Adam Huttenlocker, Ph.D. Candidate

University of Washington, Department of Biology

Further Reading:

Harries PJ & Knorr PO (2009) What does the ‘Lilliput Effect’ mean? Palaeogeography, Palaeoclimatology, and Palaeoecology 284:4–10.

Huttenlocker, A. K., and J. Botha-Brink. 2013. Body size and growth patterns in the therocephalian Moschorhinus (Therapsida) before and after the end-Permian extinction in South Africa. Paleobiology. 39:253-277. 

Metcalfe B et al. (2011) Size and growth rate of ‘Lilliput’ animals in the earliest Triassic. Palaeogeography, Palaeoclimatology, Palaeoecology 308:171–180.

Retallack GJ (In press) Permian and Triassic greenhouse crises. Gondwana Research. doi: 10.1016/j.bbr.2011.03.031

Twitchett RJ (2007) The Lilliput effect in the aftermath of the end-Permian extinction event. Palaeogeography, Palaeoclimatology, and Palaeoecology 252:132–144.

 

Northwest Developmental Biology conference

I'm in Friday Harbor Labs for the Northwest Developmental Biology Conference, with a lot of other UW people including other biograds. Kelsey Galimba gave a great talk today about her work on Thalictrum floral homeotic genes, and Jessica Guseman presented a yeast-and-auxin poster on Wednesday. Former biograd Cristy Walcher gave a talk about tomato lazy-2, which contrary to its name actively grows downward; she's now visiting faculty at University of Puget Sound. I'm looking forward to Tracy Larson's poster on adult neuron development in sparrows, too.

I also gave a talk yesterday, on my homeodomain transcription factor project. Almost concurrently, the paper was published online in Development on Wednesday. We found the gene, HOMEODOMAIN GLABROUS 2 (HDG2) though a microarray scheme involving Arabidopsis seedlings enriched in different epidermal cell types. The meristemoid cell type is really interesting because it renews itself through several asymmetric divisions, which is a stem-cell characteristic. HDG2 is very highly expressed in meristemoids, and it turns out that when you make all the other cells express it too you get meristemoids and their offspring, stomata, in all kinds of strange places, like the inside of the leaf.

And, of course, it's lovely Friday Harbor. No snow here, and gorgeous little traffic-cones of whelks. (Nucella?)

-- Kylee Peterson

Ten hundred words of biograd winners

Last week's grad student happy hour at the Burke Museum included a competition to summarize your research using only the most common thousand words of the English language, a concept recently popularized by the webcomic XKCD and carried on by Ten Hundred Words of Science. Three out of the four prizes were brought home by the biograds who entered, and I'm told there were only three bio entries total! See sponsoring organization FOSEP's post for more information on the challenge and the other great science entries. The biology winners are reproduced below.

---

Yasmeen Hussain (Grand Prize Winner)

I study the link between sperm chemotaxis and fertilization success. Eggs in animals such as sea urchins release chemicals that act as sperm attractants. Sperm use chemotaxis - that is, orientation towards the source of a chemical gradient - to find the eggs. However, it is unknown whether sperm chemotaxis directly contributes to reproductive success.

I study tiny things that are man and woman parts of an animal. The woman part talks and the man part listens. The tiny things have a conversation so that they can find each other and make babies. Some man things are better at listening than others. I want to know if the man things that are better at listening are also better at making babies.

---

Jonathan Calede (Style Prize)

The goal of my work is to investigate the taxonomic affinities of the Cabbage Patch fauna (Montana) with adjacent biogeographic regions and ecomorphological disparity across paleocommunities at the dawn of modern mammalian communities. To this end, I am building a community-wide dataset of taxonomic, taphonomic, and ecomorphological characteristics for the coeval Arikaree Group (Great Plains) and John Day Formation (Oregon). The drastic changes in global climate and the heterogeneous spread of grasslands in North America associated with the transition from archaic Eocene to modern Miocene faunas make this turnover particularly relevant to understanding the evolutionary interplay between habitat and mammalian communities and the assembly of modern mammalian communities. I undertake field work in Cabbage Patch to collect additional fossils and geological data to validate the biological analyses.

I study what’s left of groups of hair-having animals that lived a really long time ago near where we live now. I study these groups of hair-having animals because they are more like the hair-having animals we have today than the hair-having animals that lived even longer ago. They are also interesting because they lived at a time when stuff was happening and it was getting warmer, then cooler, then warmer. Today, it’s getting warmer and warmer. If we understand what happened to these really old hair-having animals when stuff happened, we might be able to know stuff about the hair-having animals we have today.

How can we learn about stuff from these old hair-having animals? I find what’s left of the hair-having animals in rocks, give them a name, and put them in groups. I do that for different places that are kind of close to one another. I end up with many names and different groups for each place. Then I look at how different the groups and names are from one place to another. I want to know if some of these places shared animals with the same name or same groups.

I hope that by understanding how different hair-having animals are across the land and how that was coupled with stuff happening we can tell how those groups of animals were put together and worked as a team (in which your friends eat you and you die and end up in rock).

---

Brandon Peecook (Presentation Prize)

I study the recovery patterns of terrestrial tetrapod assemblages in the wake of the end-Permian extinction, 252 million years ago in southern Pangaea. My research focuses on the timing of the extinction recovery and its taxonomic make-up. I also study life history traits, such as growth rate, in some of the post-extinction taxa (Dinosauriformes).

I know what you’re thinking. A man who studies dead animals looks at boring bodies all afternoon. Wrong! I use dead animals, and I mean really dead, like dead for a long, long time, to ask fun questions about life’s past. I look at how times of big death change the number and kind of animals known from a place. How long after the time of big death until groups of animals are back to normal? Are they still the same type of animals? I also study the relationships between the animals. Some of the really dead animals I study are the favorite really dead animals of many people. That means I get to have fun talking about my work with them!

---

Anyone else want to give it a try?

-- Kylee Peterson

Brad Dickerson at RealClearScience

Our own Brad Dickerson wrote an article on President Obama's "Brain Activity Map" plan:

Unfortunately, Mr. Obama’s goal of mapping how the human brain is connected will not necessarily allow us to infer how those neurons function. Many scientists who work on the stomachs of lobsters would gleefully inform the President that a group of as few as 14 neurons can instantly control different behaviors depending on the context. But, when the problem is scaled up to that of the human brain, the mind truly boggles.

Why not check it out and support Brad by commenting over there?

Women in Science

The current issue of Nature features articles and an editorial devoted to pointing out the systematic gender inequality still present in science. It's not only the effect of history: while it's true that women in many places were not permitted into higher education until fairly recently, studies are also finding that exactly equal qualifications are perceived differently depending on whether a CV is labeled with a masculine- or feminine-seeming name. So how do we level the playing field?

"to chip away at this invisibility"

Women scientists can't fix everything themselves, but it helps to stand up and inform people about what we're doing. For instance, Edith Widder's TED talk on filming the giant squid has gotten a lot of people excited.

Looks Like Science collects photos of real modern-day scientists going about their (frequently wacky) lives. Unsurprisingly, many of the young people pictured are women.

How not to do it

Most people reading this have likely seen the awful "Science: It's a Girl Thing" video. New Scientist had an article reminding us of just why (apart from the severe absurdity) it was counterproductive. Young women are found to be put off by the conflation of hyperfemininity with scientific attainment.

"That’s why you have a wife."

Studies of male scientists show that their female partners often take up family responsibilities to primarily support the men's careers, even when the women are also academics. This is frequently presented as the women's completely free decision, but what we've seen so far is that women are systematically disadvantaged in reaching higher-level positions. It's a logical decision as the system stands: bet on the partner who's more likely to attain a better salary. (Relevant video: Inequality Begins at Home.) In a fair system, though, this might also turn out differently.

So if we get professorial parity everything's fine, right?

The loss of women at higher levels is only one of many inequalities in science and society. While we're extolling the virtues of letting women past the glass ceiling, it's also necessary to remember that there are people stuck under the floor. "Trickle-down feminism" is the idea that by making privileged women equal to privileged men, all women will benefit. That's not necessarily true, and if what we want from increased diversity is truly different ways of thinking, we also need to open science by bringing in more people from different economic classes and ethnic backgrounds. Outreach to underrepresented minorities and proper funding for public schools are going to be integral parts of any effort to make science fair.

-- Kylee Peterson

Species species of the Week week #7 OR Tautonomical IGP!!!

So just for the record, I was super excited when I started Species species of the Week week because this animal is EXACTLY what I had in mind.

Check it out it's:

Velella Velella

Figure 1. Velella Velella in their natural habitat - with sunglasses.
Thanks you guys for giving tautonyms some pop-culture legitimacy!

Ok. No, of course that is the Seattle-ish Electro-pop band Velella Velella (Figure 1). I admit I don't know the story of their name, though I'm sure someone around here does, but I can only assume that the capitalization of the species name is "ironic". In fact, thanks to lack of case-sensitivity, searches for the more gelatinous V. velella are indistinguishable from those searching for the band.

Here is the Velella velella I'm actually talking about:

Velella velella

"By-the-wind sailor"

Figure 2. Velella velella for realz.

V. velella emerges as this week's tautonym, you will recall, because it is on the tautonomical menu of the Blue Dragon nudibranch(1). BUT, it is also on the menu for the Baggins snail, Janthina janthina, which is itself on the menu of the nudibranch! Tautononym intraguild predation! Sooo, what? Let me try to explain. No, there is too much, let me sum up (Figure 3).

Figure 3. Food web diagram showing Tautonymic/Tautonomic (?) IGP. The arrows show what is eating what, pointing from predators to prey. The blue dragon snail likes to eat things with similar or same genus and species names because it's cool. Food chains are sometimes parsed into "guilds", all of the things on the same "level" comprising a "guild", but sometimes it's messy, and things that compete for food also have a predator-prey relationship. Here, the nudibranch competes with J. janthina for food (V. velella), but it also eats J. janthina - which is a pretty cool strategy for reducing the competition.

In addition to sharing the distinction of feeding a sea beastie with excellent grammatical taste, V. velella also shares with J. janthina the peripatetic lifestyle of the pleuston(2). Whereas J. janthina goes the hot air balloon route(3), V. velella is a sailor - hence the common name. They are a type of jelly, so they float around, mostly (see below) passively and distinguish themselves by raising a thin, chitinous(4) plate out of the water - the sail! And if you are, like V. velella, yourself a sailor, you will intuit that V. velella's sail is not parallel to the length of its body, it's offset by a few degrees. This enables it to use its tentacles for stability and to sail off the wind(5). Here is a diagram (Figure 4)!

Figure 4. There's a caption above and a citation below to give you all the information you need on how PMW ( = Portugese Man O' War. Here they discuss the nearly tautonymic Physalia physalis, which sail similarly to V. velella) sail compared to sailboats.

Ok, so there is asymmetry, which is pretty cool for lots of reasons, but the other extremely cool thing is that they are not all asymmetrical in the same direction: there are left-sailed and right-sailed V. velella. I'm not sure that folks are yet clear about what determines whether an individual will be right or left-sailed, or at least I haven't found anything that seems clear, but they have tried to understand how this might affect their distribution. This was evidently confounding to ecologists for a long time, because papers on this question date back to the 20's. In Nature in 1959, Robert Bieri explains it thusly(6):

In the northern hemisphere, left-handed specimens of Velella move to the left of the wind direction due to the anticyclonic wind circulation over the ocean. The left-handed specimens are therefore concentrated along the outer edges of the distribution. The right-handed Velella move to the right of the wind direction and are concentrated in the centre of the distribution. Thus one should find the left-handed specimens near shore.

And the opposite is true in the southern hemisphere(7). So, all the individuals of one sail type (depending on the hemisphere) might get mass-stranded on the beach or stuck in the Pacific Ocean gyre. This could be a bet-hedging strategy - if you don't know where the food is going to be, send your kids everywhere so some of them make it - AND such a drastic difference in dispersal could have some extremely awesome evolutionary and ecological consequences....blah blah blah <-- Emily drones on and waves her arms a lot here....

As cool as this Velella Velella?

Figure 5. Velella Velella in SPL-uh.

I think so, but you'll have to decide for yourself.

References and miscellany:
(1) Well, also because friends (and brother - ever the source of blog post inspiration) kept posting V. velella on my fb page. For the record, I had already written most of this post weeks ago, and just hadn't gotten around to finishing and/or posting it.
(2) Wait, what's the pleuston, again? Well it's like the neuston, only for the big guys.
(3) OHHHH! Speaking of hot air balloons, you should really educate yourself about this mind blowing recent event!
(4) Just ignore that word if it brings back anxiety attacks of your intro bio class. I haven't ever looked into this or even really thought about it, but I'm passively interested (read: pretending to be a science hipster) in the use of calcium carbonate versus chitin in sea creatures to form hard structures.
(5) PS, I clearly don't understand too much about this, and have only a vague notion of why, exactly, one can sail faster than the wind, but for more on the hydrodynamics of the V. velella sail, see this paper.
(6) Yup, I just said "thusly". It even made me gag. Here's the citation for that paper: Bieri (1959) Dimorphism and size distribution in Velella and Physalia. Nature 4695:1333.
(7) Think the Simpsons visit Australia: Why is this only available in Spanish!?

Examining coevolution in Argentinean fossils

If you are having trouble deciding between two major fields of study, don't fret... you can always go into paleontology, where you can study multiple fields! For the last four years, my advisor, Caroline Strömberg, and I along with several collaborators from the US and Argentina have been working at a famous fossil site known as Gran Barranca, located in Chubut Province, Argentina. The project is multidisciplinary in approach, involving geology, geochemistry, paleobotany and vertebrate paleontology. Our goal was to test hypotheses about early grassland origins and the potential co-evolution of mammalian herbivores between 43 and 18 million years ago. Gran Barranca is well known for its vertebrate fossil record and it has been studied for over 100 years by renowned paleontologists such as the Ameghino brothers and G.G. Simpson. Gran Barranca is a paleontologist's dream as it preserves a long, nearly continuous fossil record of diverse South American biotas including vertebrate remains, insect trace fossils, soils and exquisitely preserved phytoliths (plant silica) all within deposits of volcanic ash that can be dated with great precision.

Here are two very recent publications describing some of our findings. In one paper, we present a new chronology for Gran Barranca using U/Pb radio isotopic dating techniques, and in the second paper we describe the ancient vegetation of Gran Barranca from phytoliths. One of our major findings is that "grazer" tooth forms seem to have evolved in Patagonia in the absence of grasslands. This idea overturns assumptions that many paleontologists have made for years about South American vegetation during this time period. Instead, it appears that grasslands are much more recent than previously presumed, in fact, we are still on the hunt for them. We are exploring other geographic areas and younger rock outcrops to answer this question. Stay tuned...

Strömberg CAE, Dunn RE, Madden RH, Kohn MJ, Carlini AA. (2013) Decoupling the spread of grasslands from the evolution of grazer-type herbivores in South America. Nature Communications 4:1478. doi:10.1038/ncomms2508 (UW Today article)

Dunn RE, Madden RH, Kohn MJ, Schmitz MD, Strömberg CAE, Carlini4 AA, Ré GH, Crowley J. (2013) A new chronology for middle Eocene–early Miocene South American Land Mammal Ages. GSA Bulletin 125(3-4):539-555.

-- Regan Dunn

Year of the Snake (part 2)

Today's snakes are from Yasmeen Hussain:

Ahh! A fluorescent snake! (It's actually a sperm from the sea urchin Lytechinus pictus.)

And me, Kylee Peterson. This is a confocal image of plant epidermis, with a stoma as the bigger snake's head and the stomatal pore as its eye. The little snake's green eye is a nucleus expressing a stomatal development gene, and their undulating bodies follow the edges of the puzzle-piece-shaped epidermal cells. Those cells were the biggest surprise to me when I started working with plants. They're actually very common -- most land plants have wavy cell edges to some extent, and they're thought to increase the strength of the epidermis.

Snake links:

Orgiastic red garter snakes are part of a children's book documenting sex and reproductive arrangements in animals with lovely, distinctive paintings.

On the other hand, pit vipers seem fine with parthenogenesis by choice.

Discovery Channel's Year of the Snake photo roundup has some very fine examples of the suborder.

Sad result of a python's external plane ride

Everglades hunt for invasive pythons

Rat snake ranges may expand with climate change

Finally, the world's longest reticulated python is a performer named Medusa who works in a haunted house. She is twenty-five feet, two inches long. I hope we all do as well as Medusa this year!