Monday, January 26, 2015

Using Phytoliths to Determine Tree Cover in Ancient Ecosystems

Ok all you dinomaniacs its time to stop fapping over massive theropods, titanic sauropods, and feathered (or non-feathered) velociraptors and talk about some boring ol' plants. And not even whole boring ol' plants even, we are talking microscopic remains of plants called phytoliths. You may or may not be aware but there has been a bit of a slow motion revolution of sorts going on in paleoenvironmental circles for some time now - and knowing about it will ultimately help in potentially viewing dinosaurs - and other extinct beasties - with greater resolution. And that should be of some interest to you if you want to really get into the nitty-gritty of paleoecology.

Scanning Electron image Phytoliths Elephant Grass Parr et al 2001
Just published in the January issue of Science, Linked canopy, climate, and fauna in the Cenozoic of Patagonia lead author Regan E. Dunn.,

Yeah, as it turns out those boring silica based epidermal cells found in loads of plants and just kicking around preserved in sediments going back to the Devonian, yeah they might just be useful as a proxy for determining relative vegetative cover i.e canopy thickness for extinct environments. And even if you could care less about plants that's pretty cool for it's potential to elucidate characteristics of extinct ecosystems and also potentially infer habitat characteristics and ecologies of extinct animals - even dinosaurs.

From redOrbit review article:

"The new methodology provides a high-resolution lens for viewing the structure of ecosystems over the  deep history of our planet. This capability will advance the field of paleoecology and greatly improve our understanding of how future climate change will reshape ecosystems." Alan Tessier, director NSF Division of Environmental Biology.

"Vegetation structure links all aspects of modern ecosystems, from soil moisture to primary productivity to global climate. Using this method, we can finally quantify in detail how Earth's plant and animal communities have responded to climate change over millions of years, vital for forecasting how ecosystems will change under predicted future climate scenarios." coathor Caroline Stromberg, curator paleobotany Burke Museum.

As an independent test the researchers compared modern phytoliths collected from a variety of closed to open habitats in Costa Rica and the observed forest cover resolved quite nicely with the collected data. So that's a slam dunk right? We can now really get a handle on what some of the famed Mesozoic environments were like.. Was the Morrison forested or more open savanna type vegetation? The Hell Creek Formation? Well as I mentioned at the beginning of the post this has been a bit of a slow motion revolution (which is fitting as plants operate in a slower pace of life) and using phytoliths has been bandied about as a way to infer past vegetation for some time.

A quick internet sleuthing on my own part revealed this paper just published last year which cautions against too literal interpretations of phytoliths and calls attention towards soil type:

So, as always, things are a little more complicated than first imagined. Furthermore how much phytolith is produced by plants is variable; not all plants produce phytoliths. Notably for those interested in Mesozoic ecosystems many conifers, including Araucariaraceae and cycads lack phytolliths. But on balance phytoliths are common in Equisetaceae (horsetails) and Selaginellaceae (spike mosses) and several types of ferns. At least according to wiki and my quick investigation.

Anyways some stuff to think about and I find these papers and paleoenvironmental topics/paleobotany stuff get's a little underreported in the general paleoblogosphere. I wanted to write more but my stomach hurts.

So here is pic I took in Northern California

Sunday, January 18, 2015

Black, White, and Red All Over: Orcas Penetrate the High Arctic

You could say I have shifted a lot of my attention and interest onto aquatic stuff lately - hey I included the word salad in the name of this blog for a reason, a salad can have all manner of toppings including seafood!! So no plesiosaur machinations today nor spinosaurid stuff although plenty more to come this year in those regards so stay tuned. No today I want to focus on extant marine creatures/ecological communities of the Arctic. Namely recent range expansion of what I consider personally the penultimate marine predator of all time (sorry Megalodon fanboys), the killer whale or Orcinus orca while Ursus maritimus - the polar bear - diminishes.

 Orcinus orca. Uploaded by EvaK. CC 2.5 Senckenberg Museium Frankfurt Germany
The polar bear, Ursus maritimus, has become a bit of a symbolic linchpin for anthropogenic global warming. As a top predator at the top of the world which is inherently dependent on pack ice as a platform to hunt it's more aquatic capable phocid prey this choice is an obvious one. As the ice goes, so does the polar bear. And in our ramped up, high velocity anthropogenically driven world ecosystem there is a bit of an asteric at the question of polar bears surviving in an increasingly ice free Arctic - can they even adapt that fast with the pace of current climate change? I do lay out one possibility here. Never the less we should not consider the possibility of an ice free Arctic or the extinction of the polar bear as the end of an "ecosystem" so much as merely the start of a strange, new one. And quick to move into and usurp the polar bear as king of the Arctic is the killer whale, a shifting of the guard we may in fact be witnessing currently and which might become a veritable reality in this century.


Compared to the three most notable Arctic whales (bowhead, beluga, and narwhal) the killer whale is at a bit of a disadvantage in ice- it has a huge dorsal fin, especially among the males where it might be 2 meters tall. So although they do move up to the edge of the pack ice in the Arctic and Antarctic they do not penetrate very far into the pack ice or areas with large amount of floating ice due to obviously painful scrapings and cuts that constant abrasion against ice would incur. So not only is ice a hunting platform for polar bears and a resting/birthing stations for seals - it a sanctuary of sorts for Arctic whales from killer whales. But a spate of incidents suggests that the sanctuary that ice provided whales in the high Arctic Canadian archipelago and Hudson Bay is no more. There is a bloodbath in paradise.

Glenn Williams. Narwhals jousting

"We saw this big bloodstain in the water", and "You could smell the blubber in the air. And the killer whales were moving onto the next one, like nothing had happened." so describes a witness to an increasingly familiar but previously rare event - killer whales moving into Hudson Bay and targeting beluga whales in the estuaries and bays that they traditionally stayed in during the summer months in relative safety. Orcas Pop Up near Churchill, Feed on Beluga.  What was at most an ephemeral and rare predatory encounter between the two species is looking more and more like a deliberate hunt by the killer whales. The ice disappears earlier and arrives later allowing the orcas to move in and stay longer. There has been the suggestion that some recovering populations are being suppressed and others may be further diminished. Sometimes the killer do not make it out of the Bay in time, as occurred last year when a pod was trapped - but eventually freed by currents.

photo credit Davidee Mina. killer whales trapped Hudson Bay
What is obvious is that killer whales are increasing their presence in the Arctic, especially the eastern Canadian Arctic, and that they are targeting more than just belugas.

Invasion of the Killer Whales. Nature PBS December 18, 2014.

The portrait painted by the above highly recommended Nature documentary is one of an ecosystem in flux. Polar bears scrounging for carcasses on the beach, sea bird eggs, and fishing for Arctic char in rivers. And killer whales moving into an ecosystem in which they had previously been kept at bay. Moving with a purpose, covering over 200 km a day to seek out narwhal populations in the Canadian Archipelago from which they could not reach before. Bowhead whales evincing massive scars and bites from killer whales and switching their movements towards areas that retain ice year round to avoid the killer whales. Playing a game of cat and mouse the two whales listen to eachother across vast expanses of ocean.

Tagged killer whales (red) versus tagged Bowhead whales (yellow) showing avoidance patterns
Bowhead fluke w/killer whale maulings
And a third archpredator of the Arctic, Homo sapiens of the Inuit culture, seeking answers and context to an archpredator which had only previously been an ephemeral visitor but which now increasingly shapes the prey and the ecosystem that they are dependent on. Will the seals and whales that this culture depends on shift range and habits to deal with their new predator? How will this affect the ability of these people to find them? Are we looking at an example of killer whales competitively excluding humans?

"I was hunting these narwhals and they were fleeing from some killer whales. The killer whales were travelling fast and upside down. And they breached the water chasing the narwhal. When they got close to the shore where the narwhal were they took bites out of two of them very quickly. This is when I realized that they are supreme hunters." Inuit elder.

"We knew changes were happening and wanted to understand them... We anticipated a change from the bottom up... We recognized the killer whale as that top predator that was all of a sudden making these huge changes in the Canadian Arctic. And it was something we didn't really think about at the start but there it was staring us in the face." Steve Ferguson, Canadian fisheries biologist on realizing that simultaneous with a bottom up trophic cascade in the Arctic a top down trophic pressure via killer whales was also occurring.

While killer whales in the eastern Canadian Arctic appear to be expanding their range to include areas westward and northward and capitalizing on prey/feeding grounds previously out of their reach between Alaska and Siberia on a group of islands called the Diomedes they have been documented predating on walrus recently. The following clip I scrounged up on Youtube is to the best of my knowledge the first video documentation of such an occurrence.

Walrus, which are themselves recognized as keystone species due to the significant bioturbation they do when digging up benthic prey and are significant in the diet of Inuit, are also highly dependent on ice for resting upon. Loss of ice concentrates walrus in large herds on the land which might further enable killer whales to find and target these large seals.

Polar bears have also been documented targeting these concentrations of walruses, although concentrating usually on the young. Another food source grounded polar bears have been utilizing during the summer months are runs of a type of arctic salmon called arctic char.

Polar Bears hunting Arctic Char. Nature
 Harkening back to their brown bear roots...

Global ecosystem change is already afoot. Some will adapt. Some will move. Some will benefit. And some will perish. How this will all play out and what surprises await who can say?

(c)US Navy. public domain. USS Honolulu 450 km (280 mi) from N. Pole

Thursday, January 15, 2015

Dog-Eat-Dog World: Theropod Wars Revisited... Morrison Style

Jim Kirkland. Juvenile Ceratosaurus Leaping on Tanycolagreus. NAMAL
The above image of provided by James Kirkland as part of a temporary exhibit at the North American Museum of Ancient Life (NAMAL) depicts a putative intraguild predatory encounter between a juvie Ceratosaurs sp. and a little known theropod called Tanycolagreus. Now, I want to avoid a discussion on whether or not Tanycolagreus is in fact a synonym of Coelurus - I'll leave that up to someone else. I want to use this picture as a bit of a springboard for a larger discussion on the obvious diversity of theropods in the Morrison and of course a fave topic of mine - niche partitioning.

Now I have discussed niche partitioning before and it's not that I 100% disagree with the concept - there is a robust body of evidence from modern contemporary ecological studies that it is a useful theory - I just think that the concept is a little too oversold in paleontology, especially dinosaur paleoecological studies. What I am trying to say here is, let me choose my words carefully, is that niche partitioning gets seized upon because it speaks to a real human need to put nature in a box. To separate and control things. But nature, especially biology, is slippery and slimy and if you try and corral it at one end it pops out at the other.  Example: dinosaur A occupies a different morpho-ecospace than dinosaur B- and voila they coexisted by avoiding competition and eating different diets!! Now, as I said earlier I do think niche partitioning is a thing and worthy of study I just think a little more nuance, elaboration, and attention to what modern animals do is worth adding to the discussion.

Let me draw your attention to two recent studies, one paleo and one ecological,  that may elaborate on what I speak of. The first one is concerning a new smallish ceratosaurine theropod from the famed Como Bluff site of the Morrison formation recently published in Volumina Jurassica (get full paper here):

Now what I want to draw your attention to is the last sentence: "... it is tenable that theropods of different clades co-existed in the same ecosystem at the same time and most likely competed for the same food sources."

YES-YES-YES!! Finally a paper talking about theropods coexisting without resorting to the knee-jerk reaction of "well they must have partitioned resources to coexist". Again niche partitioning is a useful concept, but to gage the extent that it occurred first it is necessary to really assess; 1) Is a resource really limiting? i.e. maybe there was actually enough food to go around for all without having to divvy up everything via niche partitioning. It's not hard to imagine how, even when small prey was lacking, the occasional sauropod carcass was a windfall for theropods large and small and saw them through many a tough dry season; 2) Instead of always looking at morphometrics and trying to deduce partitioning maybe the landscape itself was partitioned. And finally sometimes species compete violently and both species just continue to live side by side with no elaborately contrived niche partitioning needed. Lions and hyenas come to mind.

With number 2 in mind let me direct your attention to a study published in the November 2014 issue of Ecology (Ecological Society of America):

Ok so a lot of things to glean from this study. Both the coyote and kit fox have substantial overlap in a prey base of mainly rodents/lagomorphs but the coyote is able to exert pressure on the kit fox as an intraguild predator. However, this was not enough to dissuade kit foxes from coexisting with coyotes in the habitat with highest prey biomass (shrublands, interdunal grasslands) although the foxes were less common there than in marginal, prey poor habitats (gypsum dunes, pickleweed playa) that coyotes shunned, presumably due to their relatively higher metabolic/water needs. In both instances it was prey abundance that modulated the intra-guild predator relationship with foxes able to exist in environments unsuitable for coyotes as well as the more prey rich environments that coyotes favored. The authors note that this is the first time two intraguild predator states - coexistence and competitive exclusion - occur simultaneously in the same ecological community.

All right with that interesting study in mind - showcasing the intricacies of prey abundance, competitive exclusion, and intraguild predation - let us revisit the Morrisson. Where, depending on who you talk to, it hosted a diverse bestiary of maybe half a dozen or more theropods evolving together amidst a tangle of megaherbivores and  smaller ornithopods in a seasonal, drought prone, heterogenous landscape. One often reads of the dominance of Allosaurus numerically to other theropods - both large and small - as reflected by fossils here. How much of this numerical dominance is real and how much an artifact of some type of preservational bias? If Allosaurus was the coyote of the Morrisson, limiting itself to only the spots in the community that provided it adequate prey and water - maybe it was excluded from the more resource poor parts of ecosystem where the more moderate sized and thrifty theropods held sway ala kit foxes via competitive exclusion? The large skeletal size and proximity to water of Allosaurus would further embellish this noted abundance of Allosaurus as compared to smaller theropods which frequented less productive lands further from areas of deposition and therefore preservation. And this would help explain the noted "hidden fauna" of smallish theropods in the Morrisson... and maybe Torvosaurus as the predatory wolf to the smaller Allosaurus... food for thought.

Friday, January 2, 2015

Join the Antediluvian Salad Facebook Page!!

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In addition to getting notified for new posts I will attempt to link to interesting articles, posts, videos, artwork, pictures that further delineate and spotlight the antediluvian salad eco-morphospace in the blogosphere.

Thursday, January 1, 2015

Plesiosaur Machinations III: The Family That Slays Together, Stays Together

First of all if you have not read Plesiosaur Machination Part I and Part II, GTFO, go read 'em,  and come back. If you have please enjoy Plesiosaur Machinations III: The Family That Slays Together, Stays Togetether (intentionally misleading title).

Ahhhh the holidays... did you feel that family togetherness, or maybe not so much? Whatever your particular situation is you can rest assured that the complicated emotions we feel, that are likely heightened this time of year, are a direct consequence of our mammalian social heritage, limbic system, and neocortex. But it is the limbic system, sometimes referred to as the "paleomammalian brain", that is most intimately associated with emotions. But the term "paleomammalian brain" is a bit of a misnomer as it implies only the synapsid line of tetrapods developed this emotional brain. Birds have their own version of the limbic system and it has increasingly become apparent that reptiles have a limbic system as well suggesting that the evolution of the limbic system occurred after the split of amphibians to reptiles. And given the recent revolution in reptile social behavior and, dare we say, emotional capacity this should not be so much of a surprise that reptiles have a (limited) emotional capacity. Given our history of trying to separate ourselves from other animals and having only so recently admitted alliance with primates - maybe we are still recalcitrant in allowing reptiles such a capacity for emotion which we link with ourselves, mammalia, and "higher" brain function?

But let us not get carried away here - no need to feel that you have neglected the brooding artist inside of your pet bearded dragon. If we count hate, love, lust, fear, anger, and contentment as the base emotions from which they are elaborated upon in mammals and birds - especially when used in conjunction with the neocortex - then reptiles would certainly fall under the banner of emotional animals, however diminished in capacity and variety as may be when compared to mammals. And as was discussed in the last post, several species of live-bearing lizards provide a model for how viviparity may have fostered a social bond in plesiosaurs. Here I want to consider how the emotional state of contentment achieved via  physical contact may have further solidified the social bond in plesiosaurs. And that an animal need not develop an expanded neo-cortex to achieve this blending of the social and emotional.

By Ampatent. St Louis Zoo. C.C.Attribution-NoDerivative Works 3.0 License

And then as now I would posit physical touch as the medium through which the social bond was consecrated in the extinct marine sauropterygians. A simple bio-physical chemical feedback loop reinforced via the winnowing effects of Darwinian evolution. The plesiosaurs that seek out and engage in physical contact with members of their own species, reinforced chemically by a presumed oxytocin like chemical,  stand a better chance of surviving than those that don't. No need to evolve a highly modified, derived mammalian type brain. The reptilian brain is good enough. Now diving into the wormhole of what chemicals may have enhanced the bonding experience - some sort of oxytocin "cuddle" type hormone or equivalent, most likely vasopressin - is an interesting question and one that is only minimally explored in modern reptiles. I myself don't feel qualified enough to offer any thought on this aspect of bio-chemical cuddle hormones but there is certainly the potential that some type of hormone fulfilled this role in plesiosaurs as suggested by modern phylogenetic bracketing.

And to the organ most useful in maintaining social cohesion and contact in plesiosaurs - that long dangly neck of course!!

A Touch in the Void by Duane Nash
With the body and flipper usually engaged in swimming the neck of plesiosaurs offers a useful organ to maintain physical contact and proximity with other members of the plesiosaur phalanx. This contact can be maintained while at rest, while traveling, and even while foraging. It is important to conceptualize the vastness, the isolation, the existential dilemma of living in the open ocean. Even to a 13 meter long elasmosaurid, equipped with a reptilian brain, the vastness of the Mesozoic oceans must have felt daunting. And the reassuring touch of another member of it's kind may have done much to assuage this sense of vulnerability and isolation. If we take this notion of kin-based social bonding in plesiosaurs to it's logical conclusion - a very touchy-feely bonding mechanism seems most likely. And one is forced to genuinely consider the probable likelihood of giant marine sauropterygians (and maybe many other extinct. live-bearing marine reptiles) engaging in what can most accurately be described as emotionally based, physical touch mediated bonding activities. And in this manner becoming eerily, maybe creepily, convergent to the well established physical bonding practiced by many cetaceans - most famously dolphins.

Which is not so strange is it when we commonly cite convergent evolution in terms of anatomical adaptations in disparate groups; why not convergence in social behavior when similar environmental/reproductive constraints are placed on distantly related tetrapods?

Wiki commons. Bottlenose mother/infant. M. Herko
Spinner Dolphins. Sunphol Sorakul. CC 2.0
Ebony & Ivory By Duane Nash
And I leave you with Dave and his big pet black throated monitor Big Boy.

Happy New Year and don't forget to hug a reptile!!

Saturday, December 27, 2014

Don't Draw Celibate Cycads!!

One does not have to look far to get into the well documented, especially on the paleoblogosphere, interplay between paleontology/paeoartistry/plagiarism/tropes etc. etc. Chances are if you read this blog you are aware of this crucial and ongoing debate especially as it pertains to certain tropes or memes that seem to get repeated, maybe even subconsciously, with regards to certain peculiarities or assumptions about the life appearance of extinct animals (esp dinos). And I don't really want to bother with a list of links to this ongoing discussion here although for starters there is the All Yesterdays movement, The Paleopolice FB/deviantart group, Support original Paleoart, and so on and so forth. What I want to do on this post is focus on the dilemma of "the celibate cycad".

A bit of a qualifier here. Not that there is anything particularly wrong with depicting a cycad alone on the landscape or even utilizing what I refer to as "the big three" (ferns, cycads, conifers) in Mesozoic landscape - it is a question of representation and over utilization, especially when alternate views are more or just as defensible. In the past I made the same argument with dinosaurs always conveniently framed on a bare patch of dirt. Now, truth be told I can't take 100% credit for noting that very common trope - I recall first hearing it mentioned in an online discussion somewhere - but I do think it is worth noting and it is unabashedly common once you start looking for it. Again, not that there were no bare patches of ground in the Mesozoic and not that dinos did not stand on them - conveniently framing themselves - it is a question of this view being over represented. And, while it is true that this meme repeats so often as a function of the artist framing the main subject which is the animal, after a while this repetition becomes a disservice because it does not speak to the full mosaic of ways in which animals, even large ones, clamber through, hide in, and engage with the vegetation in their respective environments.

(c) Gregory S. Paul
(c) Conway
(c) Troco
All three above images, beautiful and illuminating in their own rights, all depict the dinosaur conveniently framed on a bare patch of soil meme.

And so onto the problem of "celibate cycads". I first heard the term "celibate cycad" in an article by Jennifer Frazer titled Are Cycads Social Plants? Now I have discussed this concept of large herbivore mediated cycad dispersal before here but to recap cycads are a bit of an enigma - slow growing, toxic foliage and large seeds with a fleshy, nutritious outer coating called a sarcosta but somewhat analogous to angiosperm "fruit". It has been surmised that the large seed serves two purposes - small dispersers such as monkeys, possums, rodents etc etc. will tend to move the seed not too far from the parent plant. This increases the chance of the seed growing up in the vicinity of other cycads and, because they are "sexed" plants with a male and female plant and pollinated by insects, enhances the chances of reproductive success. This explains why cycads do not invest in bountiful numbers of cheap, small seeds which would tend to be dispersed further from other cycads and thus grow up isolated and celibate. For large dispersers - flightless birds, giant marsupials, dinosaurs - many "fruits" can be swallowed whole and then deposited en masse in the animals dung and thus setting up the potential for a new grove. What is important to keep in mind is that whether it be via small or large animal mediated dispersal grove formation is encouraged in both scenarios. Further supporting this scenario is the tendency of cycads to mast reproduce concurrently to attract pollinators and dispersers in numbers.

2013. Hall & Walter. Macrozamia Miquellii. Mount Archer Park, Australia

And so this tendency to grow in groves and reproduce concurrently is an attribute that paleoartists should take note of when depicting Mesozoic landscapes. It is especially important if one makes the defensible speculation that dinosaur herbivores/omnivores were commonly attracted to these mast cycad fruiting events as a source of food. Or possibly pterosaurs, mammals, sphenodonts, and crocs as well.

Arjay Bee
So are "celibate cycads" a problem in paleoart? I would say after looking over the vast majority of paleoart that no, most artists get cycads right with regards to depicting them most commonly in groves. But it is something to be aware of. I would love to see more of an emphasis on cycad groves as a common micro-habitat in Mesozoic landscapes.

However I would be remiss not to highlight the growth in popularity and utilization of digital artwork, especially per the influence of Julius Csotonyi, and possible problems there of. One of the main flaws in Julius' work as it pertains to vegetation is his plants are often vibrant green and look maintained as if in a park or garden - and this may have to do with the source photograph was from a park/garden. I have heard this criticism before but it bears repeating. Case in point here where the cycads are missing a skirt of old/dead dying leaves and some are borderline celibate. Also this one here which depicts several possible celibate cycads. And given their slow growth rates I don't place a lot of faith in cycads being common plants near riparian areas and dinosaur nesting grounds which are both prone to disturbance. And Julius also loves to put his dinos on a bare patch of dirt. Now I don't want to pick on Julius too much - I am not the hugest fan of digital art but Julius does a better job than most with it and I am a fan of his & his book -  but we should not be caught unawares that when certain artists get heralded as the "top of the line" that it is these exact artists that are the ones that most need to be looked at under a critical eye. This is due to the simple fact that these artists will have a proportionately greater influence than others over time. Whatever biases and flaws are imbued in their work, and history suggests that there are always some (see GSP and shrink-wrapping), will be co-opted by future artists. And this constant nit-picking of the top of the line artists will further refine the interplay of science and art in the future.

Cycas media. Tanetahi

Coming Soon: Don't worry loads more plesiosaur machinations coming up, if you liked the first two then lots more where they came from and IMO will get better and more interesting with time. Also if I don't post anything new before the New Year loads of more stuff planned for next year including some thought pieces and interpretations brand new!! Thanks for spending your time here consuming content when you could have spent it elsewhere in the unlimited free content world we live in. About to hit a quarter million unique page views!! Thanks

Tuesday, December 16, 2014

Plesiosaur Machinations II: The Social Sauropterygian

I find persistent natural history myths, anecdotes, and adages a topic of special interest. These  narratives, stories, adages and anecdotes - usually unsupported by detailed field work and not part of the technical literature - are usually just that, fictional stories, and easily dismissed. However sometimes such popular stories, especially when sourced from people who spend much time in the company of the animals in question, may offer some element of truth. For instance I was talking to a friend of mine who regularly goes deep sea fishing and he told me he prefers to use squid as bait - because brown pelicans (Pelecanus occidentalis) assiduously avoid eating squid. I investigated further and came across an interesting video on youtube suggestive of such avoidance and then went to talk to some squid fishermen at the local harbor (in recent years the squid fishery has been thriving in California waters). The squidders all assuredly and confidently replied no - pelicans do not attempt to pilfer or eat the squid from their catch. Gulls yes, pelicans no. Why is this? The fishermen thought is was because pelicans do not want to consume the internal "pen" of the squid. But I found this argument unconvincing, brown pelicans eat whole fish with loads of bone after all. Brown pelicans, unlike the white pelicans in my last post, plunge from height into the water and engulf prey and water in their pouch. The brown pelican then has to drain out the water in its pouch before swallowing the prey. When a pelican engulfs a mouthful of fish - no problem - but if a pelican engulfs a mouthful of squid it's a different story. At this point the squid can latch onto the inside of the pouch with their suckers or even obstruct and block the throat of the pelican  and thus represent not just a nuisance but a real and obvious choking hazard. Again, nothing in the technical literature on this topic but maybe some element of truth to these anecdotal observations.

And now for another interesting adage regarding peculiar natural history behavior, this time from Australia, and that is that abundant lizards, specifically larger skinks, can keep snakes out of an area. And you can find this sentiment repeated at several places on the interwebz. At first glance it seems that it should be easily dismissed. Indeed one can offer the argument that the opposite is more likely - abundant lizards should attract snakes as potential prey. Never the less, can this story offer some element of truth? The answer is yes, yes it can.

King's Skink chasing Dugite

The King Skink: Snakes Beware!!

Lesley Jackes. communal King's Skinks

Sociality in lizards: family structure in free living King's Skinks Egernia Kingii from southwestern Australia (C. Masters & R. Shine)

Abstract. King's Skinks Egernia kingii are large viviparous scincid lizards from southwestern Australia. Although some other species within the genus Egernia are known to exhibit complex sociality, with long-term associations between adults and their offspring, there are no published records of such behavior for E. Kingii. Ten years' observations on a single family of lizards (a pair of adults plus six successive litters of thier offspring) in a coastal suburban backyard 250 km south of Perth also revealed a very stable adult  pair-bond in this species. The female produced litters of 9 to 11 offspring in summer or autumn at intervals of one to three years. In their first year of life, neonates lived with the adult pair and all the lizards basked together; in later years the offspring dispersed but the central shelter-site contained representatives of up to three annual cohorts as well as the parents. Adults tolerated juveniles (especially neonates) and their presence may confer direct parental protection: on one occasion an adult skink attacked and drove away a tiger snake Notechis scutatus that ventured close to the family's shelter-site. Although our observations are based only on a single pair of lizards and their offspring, they provide the most detailed evidence yet available on the complex family life of these highly social lizards.

So, some lizard curious citizen-scientists decided to go all Jane Goodal on a family of King's Skinks living in their backyard and they document a monogamous, multi-generational, highly social, cohabiting, and offspring defending lizard!! And observed an adult attack and drive away a highly venomous tiger snake!! From the paper, regarding predation and the tiger snake interaction:

We have not observed predation nor found carcasses of skinks within the backyard. However, the lizards responded rapidly to birds flying overhead, with the smaller skinks fleeing first while the adults often remained in place on their basking sites. The skinks showed no overt reaction to bobtail lizards Tiliqua rugosa that occasionally moved through the backyard but we witnessed one vigorous interaction with another reptile species in April 1999. The larger adult E. kingii was found entwined and rolling over and over with a tiger snake Notechis scutatus only slighly longer than itself. When the two reptiles separated, the snake fled with the skink in hot pursuit. The skink later reappeared with no overt injuries.

Now, there are lots of neat stuff in this paper that will be revisited later but jeez, that tiger snake interaction was pretty cool. Going further from the discussion section:

The observation of an adult E. kingii fighting a tiger snake is particularly interesting. The snake was too large for the lizard to ingest (indeed, adult E. kingii are primarily herbivorous: Richards 1990) and the lizard was too large for the snake to ingest. The obvious inference is that this behavior constituted direct parental protection of offspring (which were ingestible-sized for such a snake, and would be acceptable prey for this snake species: Shine 1987). We are unaware of any previous example of such behavior in lizards or snakes, apart from an increase in aggressive responses to an intruder by postpartum rattlesnakes (Shine 1988; Green et al. 2002; see also anecdotal reports for other viperid snakes, summarised by Greene et al. 2002).

And if you want to see a series of aggressive attacks by a large King's Skink on another venomous snake called a dugite (Pseudonaja affinis) check out the two clips below. Filmed on a beach in Australia: my favorite part is the view of the barely interested Aussies looking on like, "Oh a giant lizard battling a venomous snake on the beach? I thought you were looking at something we don't see every day!!"

In both instances the interaction was clearly not about food, competition or territoriality - the inference to make is that the snake represented a threat to the progeny of the King's Skink. So although lizards in general won't keep snakes at bay here are at least two instances that might support the notion that keeping a stable of King's Skinks in your backyard or on your beach might help keep the local snake population slithering along to other places...

Besides the benefits of parental protection, the progeny of these sociable skinks also are privy to choice basking and shelter sites which may be at a premium in their environment. Looking at another sociable skink, the great desert skink  (Egernia kintorei), also viviparious, we see direct benefit given to offspring in the form of residence in extensive burrowing systems that extend up to 13 meters wide, have over 20 entrances, and offer refuge from predators and thermal extremes.

Lizards Cooperatively Tunnel to Construct a Long-Term Home for Family

All right so we can see that there might be some linkage between live birth, harsh conditions, and lack of critical refuge sites and theses factors are good Darwinian reasons for the unconventional social arrangements of skinks of the genus Egernia. And such behavior has even been suggested to be plesiomorphic for the group as a whole. Are there any examples of social lizards that give birth to live young and live in harsh environs that might offer a more independent test? Well yes, yes there is: the desert night lizard (Xantusia vigilis). The discovery of said animals' social behavior is of some interest to me because the researchers are from my alma mata UCSC, and also it is a California species.

Photo credit Mitch Mulks. Desert Night Lizard
Family Ties Bind Desert Lizards in Social Groups. Science Daily. 
Paper Here

Evidently this fairly small, viviparous lizard is extremely sedentary and usually lives most of its life in a fairly small home range. During winter months parents and offspring cohabited under highly localized fallen Joshua Tree logs and other vegetative debris. Offspring delayed dispersal from 1 to 3 years and remained in close proximity to parents although they foraged for themselves. Theses nuclear family aggregations were shown to be stable over several years although the exact benefit is unknown. But the researchers did highlight the link between live birth and social behavior suggesting kin-based sociality is a by product of live birth.

From the Science Daily article: According to (Alison) Davis (lead author), about 20 lizard species are thought to form family groups, and only two of those lay eggs. Viviparity (live birth) is crucial for the evolution of cooperative behaviors, she said.

"Viviparity provides the opportunity for prolonged interaction between the mother and offspring, which predisposes the animal to form a family group," Davis said. "The importance of parent-offspring interaction fits with what is currently understood about evolution of family groups and cooperative behavior in birds and mammals."

Although only recently revealed, viviparity neatly bookends the evolution of sauropterygian evolution in the Mesozoic. A Nothosaur from the middle Triassic and a polycotylid from the late Cretaceous both provide solid and iron-clad evidence of live birth in plesiosaurs and that the adaptation goes back very early in the lineage. Furthermore, the relative large size and single offspring in utero for the polycotylid suggests a very strongly developed k-strategist. This species at least does not appear to have been birthing high numbers of relatively small, live offspring - but investing heavily on a single, large offspring.

O'Keefe & Chiappe 2011

"Many of the animals alive today that give birth to large, single young are social and have maternal care. We speculate that plesiosaurs may have exhibited similar behaviors, making their social lives more  similar to dolphins than other reptiles." Robin O'Keefe, one of the authors of the paper: Viviparity and K-selected life history strategy in a Mesozoic marine reptile. Science 2011.

It should be noted that this view of social plesiosaurs has been met with skepticism. Sharks, which are  also viviparous but don't practice extended maternal care, may be better analogs, some have offered. However no sharks give birth to a single offspring. Plesiosaurs were diverse animals, can we really assert sociality as a whole for the family? Here I partially agree, there was likely a range of smaller offspring-larger brood-less maternal care to larger offspring-smaller brood-more maternal care/extended family bonds among plesiosaurs. But what we are trying to get at is a baseline from which behaviors may deviate towards other extremes. And I think the baseline for aquatic sauropterygian is strongly skewed towards maternal care and sociality. But what about the abundance of immature plesiosaur/elasmosaur recovered from coastal/lagoonal/freshwater deposits/ Could the mothers have been depositing them there and letting them mature on their own in such habitats? Possibly, but various cetaceans such as grey whales/humpback whales are known for utilizing warmer/nearshore/lagoonal habitats to birth their offspring. With occasional stillbirths and/or predator attacks at this vulnerable stage of life we should expect more immature individuals to be represented in such habits.

Of course science, like politics, is a funny thing is that it takes a compelling amount of evidence and effort to overturn previous - even dogmatic - sentiments. And even when this evidence arrives it does not take root immediately but may take several years or even decades to gain traction (case in point feathered dinosaurs). Sometimes it requires the most vocal opponents to well, how should I put it, to die... Who gets to decide what is the most conservative, parsimonious behavior for a group of extinct animals? Plesiosaurs are reptiles and the overwhelming majority of reptiles practice minimal to non-existent parental care. However when we invoke live birth, especially of a single large offspring, the balance of power shifts a bit with a number of viviparous reptiles offering evidence of parental care. When we invoke social behavior and we see that the overwhelming majority of kin based/social reptiles are also viviparous, k-strategists this further speaks to high levels of sociability probable in plesiosaurs. For me the implication is clear - like the skinks and desert night lizards discussed above plesiosaurs were social animals and invested in their offspring (and I am not the first to suggest this). Trying to retrieve a "typically reptilian" social, reproductive, and ecological adaptation for plesiosaurs has become the more untenable stance to take in my view.

Although the obvious comparison to make is between highly social mammalian toothed whales and plesiosaurs I do not think we need to invoke large brained mammalian analogs over what we can glean from contemporary social reptiles such as Egernia and Xantusia. And again, I am not the first to suggest this - O'Keefe: "a more helpful comparison (than mammals) to the plesiosaur may be the monkey skink or the shingleback skink in the Egernia group. These green, scaly lizards give birth to live offspring, one or two at a time, and are among the few known reptiles to function within a social group and care for their young." In short we do not need to try and resolve how a relatively small brained, limited intellect reptile such as a plesiosaur engaged in elaborate social behavior - several extant reptiles offer the context for how such an animal may have behaved socially, and they do not require delphinid levels of intelligence to do so.

Going back to the examples of the King's skink, desert skink, and desert night lizards which I discussed earlier I find it important to highlight another factor that may have helped push these lizards into the social realm and that is that critical microhabitats - shelter sites, basking sites, burrows - are at a premium and by living in extended families there was a net genetic benefit to the lizards that cohabited these areas with their kin. Juveniles did not have to disperse until several years of age to new sites and therefore minimized predation risk. The island night lizard depends on highly localized fallen joshua trees/yucca clumps/piles of dead vegetation to seek shelter and food under; the King's skink dependent on shelter sites/basking sites; and the desert skink on large, complex subterranean burrows. Taking these observations and applying the idea of critical refugia to plesiosaurs presents a problem; there is no where to hide in the open ocean. And so, with the observation of the venomous snake wrangling King's skink in mind, I am going to piggyback on that observation and suggest that plesiosaurs were not fleeing from the first sign of danger - but standing their ground, facing, and fighting - en masse - any potential predator. They moved aggressively in phalanx formation to danger. This is the paradigm of the earlier depictions of plesiosaurs I alluded to in my last post where I suggested that these earlier renderings of plesiosaurs - battle ready, pugnacious, and ready to throw down with any other denizens of the deep - offer >much more truth< than more contemporary works that seem to always portray plesiosaurs as the ill-equipped cannon fodder of the much larger, dominant, and aggressive predators they lived with. Pictures like this one, this one, this one, this one, even birds, and this one. It seems everywhere you look plesiosaurs are getting their asses handed to them, usually with those poor, dangly "oh so vulnerable" necks taking the brunt of the abuse. And yes we do have evidence of plesiosaurs being scavenged by sharks, a Tylosaurus swallowing a polycotylid (not even a long necked plesiosaur), and some suggestive tooth marks on the skull of Tuarangisaurus possibly from a pliosaur (Sven Sachs, 2004 Tuarangisaurus australis... Memoirs of the Queensland Museum available online). And I know I read about possible mosasaur damage to a Mauisasaurus but can't find the ref?... But as far as I can tell no suggestion of neck trauma stemming from predation among all those long necked forms....

And I will suggest that, when in phalanx, plesiosaurs were no easy pickings. Even very large predators will give up the hunt when the element of surprise is lost, their prey detects them, and has the armament to fight back. A Hainosaurus that drives home the attack on a phalanx of elasmosaurs and loses one or both eyes in the process has substantially lowered its own value in the  Darwinian sweepstakes. Lions often back off from herds of cape buffalo that stand and fight. Crows mob and drive off eagles. Sea lions will mob and harass great white sharks. And King's Skinks drive off venomous snakes.

Here I depicted a phalanx ( I am just going to start using that term instead of pod and hope it catches on, thanks Bk Jeong) of indeterminate Microcleidus sp. facing down and nipping at an intrepid Rhomaleosaurus sp. As you can see any headlong rush into such a group is going be a painful experience with no guarantee of capture. Furthermore, like herons when cornered and unable to fly, there is no reason that plesiosaurs could not have targeted the eyes of would be assailants. And when visually dependent predators lose an eye, not a good thing. Plesiosaurs were most vulnerable from the rear and you will notice I gave their stumpy, skink like tails eye spots. Furthermore the very solid and almost carapace like constuction of plesiosaur torsoes offered additional protection from rearward attacks. Microcleidus is a pretty cool but seldom discussed plesisoaur. It was basically an elasmosaur before it was cool to be an elasmosaur. Only about 3-4 meters long it had an exceptionally elongate neck, small head, but that head and jaw was nasty.

Microcleidus from Brown, Vincent, Bardett 2013

And below I depicted some more well known characters - a generic elasmosaur type plesiosaur family faces down a generic mosasaur stalking one of the youngsters.

As I went over in my last post, Introducing the Plesiosaur Phalanx Attack, a strong social adaptation in plesiosaurs offers a compelling foraging strategy. And such a social framework also offers a strong defensive strategy. Furthermore, by invoking this defensive adaptation a lot of the problems in plesiosaur anatomy that suggest high vulnerability to predation - long vulnerable neck, low maneuverability, low swimming speed - are squashed. The neck and head are not the most vulnerable spots in this scenario but instead the torso, rear flippers, and tail are. A large, plump tail would serve as a dispensable organ and may have been covered in eye spots or even shed (highly speculative?!?) to distract predators like many modern lizards. And the torso is heavily reinforced with a bony wall of ribs, gastralia, shoulder and pelvic girdles. Instead of a paradoxical animal, vulnerable on all levels to predation, seemingly outside the bounds of Darwinian evolution - a much more dynamic, capable, and combative animal emerges.

In short, a rare example, where the early artists got much more right in some regards than contemporary artists.

Édouard Riou from the 1867 edition of "Journey to the Center of the Earth"

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