My 2010 Booklist Part 2 of 3: May-August

21 08 2010

Good tidings and well-wishes!

I hope that everyone had an enjoyable summer! Having finally returned from my long but entertaining pilgrimage to an internet-bereft region of the Adirondack mountains,  I’ve managed to at long last acquire an adequate chunk of time with which to update my oft-neglected blog! Given the aforementioned lack of my primary source of electronic entertainment, I was able to engage in an obscene amount of reading during this segment of this year’s literary trimester. And so, without further ado, I hereby present the second installment of my 2010 booklist. Enjoy!

Why Size Matters: From Bacteria To Blue Whales By John Tyler Bonner

My Thoughts: At a mere 7.5 inches in height and 176 pages in length, “Why Size Matters” is, amusingly (and somewhat ‘appropriately’), one of the smallest volumes to grace my bookshelves. Bonner has done an admirable job of explaining how an organism’s size affects everything from its physiology to its ecological role to its evolutionary pathways. Of particular interest are his sections concerning how size influences one’s voice, intelligence, and longevity. While his writing style is somewhat needlessly vague on occasion, it contains a delightful exuberance along with a reverence for philosophy and literary fantasy. On the whole, “Why Size Matters” is perfect for any scientifically curious bookworm in search of a light, but informative, read.

Swimming In Stone: The Amazing Gogo Fossils Of The Kimberley By John Long

My Thoughts: It’s damnably difficult to track down good popular science books about the Devonian! So I was naturally quite excited to have found this excellent diagnosis of one of the most vital and intriguing fossil localities on the planet: the Gogo site of the Western Australian Kimberley formation, home to some of the most amazing ichthyological organisms known to science. Long is one of the paleontological community’s leading fish experts, and his passion for these creatures shines through every word of his prose. Of particular interest is one of the book’s concluding chapters in which the author defends the idea that the vast majority of significant evolutionary breakthroughs which ultimately produced the tetrapod design with which we’re intimately well-acquainted occurred millions of years before the first land-dwelling vertebrates. Additionally, while a number of non-technical science books are erroneously cited as possessing a great sense of humor, “Swimming In Stone” actually delivers in this regard, sporting several genuinely funny passages which chronicle the author’s frequently bizarre experiences throughout his career, all of which congregate to paint a wonderful image of the sacrifices and rewards familiar to those who strive to dedicate their professional lives to paleontology and it is these individuals who I believe will enjoy this exquisite volume the most.

“Frozen Earth: The Once And Future Story Of Ice Ages” By Doug Macdougall

My Thoughts: “Frozen Earth” is a book which can perhaps best be termed “uneven”. It does an absolutely impeccable job of explaining the history of ice age climatology and the field’s pioneers, yet it doesn’t always satisfactorily explain the science’s underlying concepts and evidence to a lay reader such as myself. If paleoclimatology isn’t your forte, be prepared to re-read several important passages in order to ensure comprehension. However, during those occasions wherein Macdougall succueeds in his goal of disambiguating this complex information, he does so with the grace and intrigue of a truly masterful science communicator. Additionally, “Frozen Earth” contains the finest descriptions of the Permo-Carboniferous ice age and the Snowball Earth theory/controversy that I’ve ever come across in a popular science book and its discussion regarding the adverse effects of global warming upon our environment is not to be missed by anyone who cares about the planet and its inhabitants, including ourselves. Nevertheless, in overall retrospect, I simply wish that Macdougall had dispersed his descriptive powers more uniformly.

“How To Build A Dinosaur: Extinction Doesn’t Have To Be Forever” By Jack Horner & James Gorman

My Thoughts: “How To Build A Dinosaur” is a book which has been turning heads throughout the paleo-blogosphere since its initial publication last year, and for good reason. Though many reviewers, including yours truly, initially feared that Horner and Gorman’s latest literary escapade would prove itself to be little more than a compendium of pseudoscientific twaddle, it’s turned out to be no such thing. Instead, “How To Build A Dinosaur” is a concise, comprehensive, and quite readable introduction to “evo-devo” and the fledgling science of molecular paleontology. The piece de resistance, however, is the book’s excitingly plausible central thesis. This idea maintains that given the ancestry of modern birds from small, nonavian theropods, one could theoretically  isolate the developmental routes which emerge during embryonic growth and separate the former group’s gross anatomy from the latter’s. Just like their Mesozoic forebears, all present-day birds such as chickens begin to develop long tails early in their ontogeny. However, the accumulation of subsequent mutations during the course of their evolution has resulted in the acquisition of molecules which “switch off” the maturation of this tail, reducing it to the mere stub with which poultry farmers have long-since grown familiar.  Were the precise location of these deactivation molecules unearthed, their functionality could be neutralized, resulting in a chicken with an extensive tail. Similar measures could be taken to create chickens with clawed hands, toothed mouths, and scaly bodies. Ultimately, through this ingenious technique, a little creature nearly indistinguishable from a nonavian theropod could be brought into the world. Needless to say, I’ve elected to grant this volume my fullest endorsement, such as it is. A definite must-read!

“Snakehead: A Fish Out Of Water” by Eric Jay Dolin

My Thoughts: Those turning to “Snakehead”, a book dedicated to the public frenzy surrounding the 2002 discovery of a population of namesake Chinese fish scientifically known as Channa argus lurking about a secluded Maryland pond, in search of a quick biological read are bound to be amused but ultimately disappointed, for it’s most informative commentary is instead reserved for the mainstream media and its regrettable habit of instilling undue panic throughout the populace. While this is most assuredly an issue worthy of further discussion, Dolin tends to dwell upon journalistic irresponsibility at the expense of addressing the worldwide pandemic of invasive species: although his book has an irritating tendency to reprint articles, satirical sketches, political cartoons, and panel discussions about the 2002 C. argus infestation in their entirety without regard for redundancy, its prose dedicates a mere handful of pages in the introductory and concluding chapters to examining the larger issue at hand. Still, for those in search of a light-yet-evocative summer read, “Snakehead” is a good place to start.

“Zeno And The Tortoise: How To Think Like A Philosopher” by Nicholas Fearn

My Thoughts: “Zeno And The Tortoise” purports to be an introduction to philosophy equipped with a pronounced emphasis on developing an appreciation for the thought experiments and formulas created by the discipline’s greatest minds from ancient Greece to the twenty-first century. Unfortunately, however, Fearn has here succumbed to the widespread literary pathology of poorly executing an exquisite idea. This regrettable situation is chiefly the result of his vague and often impregnable prose which manages to inhibit clarity at nearly every turn: a style whose marriage to an explanatory book concerning a subject as complex and all-encompassing as philosophy spells disaster for the novice reader. Additionally, “Zeno And The Tortoise” gives virtually no mention of any sort to eastern philosophers and thus does a great dis-service for those attempting to widen their knowledge of this magnificent field on the global level. Nevertheless, Fearn’s individual chapters often serve as an impeccable review of philosophical concepts to those who had previously encountered their individual concepts: I, for example, was able to absorb his declarations concerning relativism, rationalism, utilitarianism, falsifiability, and the limitations of reasonable doubt with comparative ease, given my prior exposure to all five notions elsewhere. The book’s greatest asset to the completely clueless reader (or partially clueless reader such as myself), however, is unquestionably its “Further Reading” section which prescribes a handful of external sources through which one might obtain additional information about each chapter’s content at length. This segment notwithstanding, “Zeno And The Tortoise” should be viewed as a study guide for dedicated students of philosophy rather than a venue through which beginners may gain exposure to its various teachings.

“Dinosaur Odyssey: Fossil Threads In The Web Of Life” by Scott D. Sampson 

My Thoughts: Despite this blog’s well-documented bias towards Cenozoic mammals, my initial fascination with the field of paleontology was, as with many of its other enthusiasts,  initially sparked by an impassioned love of dinosaurs which persists unhindered to this day. “Dinosaur Odyssey” is a book which captures the essence of this infatuation by expressing a reverence for the romanticism of these incredible beasts throughout an easygoing venture into the remarkable and frequently humbling discoveries of their study. The explanatory power of each chapter’s analysis into a plethora of such  intricate paleontological, ecological, and evolutionary topics concerning this most remarkable group as their emergence, predator/prey relationships, metabolic rates, sexual displays, and near-extinction  is rivaled only by its exuberance and ardor. Furthermore, Sampson’s concluding segment about why paleontological science matters should be considered an absolute must-read for anyone who professes to care about the discipline and its future. “Dinosaur Odyssey” is that rarest of books which I can honestly recommend to everyone ranging from those in possession of so much as a hint of interest in dinosaurian paleontology to the discipline’s seasoned veterans and practitioners.

“A Sand County Almanac And Sketches Here And There” by Aldo Leopold

My Thoughts: Last February, I reprinted Aldo Leopold’s “On A Monument To A Pigeon”: a humbling and awe-inspiring essay concerning the philosophical implications of the passenger pigeon’s (Ectopistes migratorius) infamous extinction at our hands during the late eighteenth and very early nineteenth centuries. The exquisite nature of its prose and arguments inspired me to seek out “A Sand County Almanac”: a congregation of several dozen such ecological and environmental essays which homogeneously maintain an underlying philosophy of reverence and appreciation for the natural world and our fellow inhabitants therein. Of particular intrigue are “January Thaw”, “Thinking Like A Mountain”, and “The Land Ethic” for their magnificent exemplification of this worldview. My only true criticism of “A Sand County Almanac” stems from no fault of Leopold’s but rather its posthumous publication. Due to the fact that these essays were compiled merely a year after the death of their author, they’ve been subjected to little if any editorial supervision, which enables the book’s content to grow redundant when read from cover to cover. However, this is but a microscopic blemish upon the face of a truly epic volume whose effects upon the American conservationist movement rival those of Rachel Carson’s “Silent Spring” in proportion and durability.

“The Second Bill Of Rights: FDR’s Unfinished Revolution And Why We Need It Now More Than Ever” by Cass R. Sunstein

My Thoughts: In the words of Lester Ward, “Those who denounce state intervention are the ones who most frequently and successfully invoke it. The cry of lassiez faire mainly goes up from the ones who, if really ‘let alone’, would instantly lose their wealth-absorbing power”. This most divisive of contentions is  magnificently defended by Sunstein, an eminent constitutional scholar and historian. “The Second Bill Of Rights” was the informal name bestowed upon a series of, in Sunstein’s words, “constitutive commitments” (that is, ideals protected by the day’s prevailing interpretation of the nation’s constitution rather than the document itself) designed to domestically heed FDR’s famous observation that “freedom from fear is eternally linked with freedom from want”. In other words, if America were to avoid descending into a pitifully uneven state that could easily fall prey to the likes of totalitarian forces such as those which had previously swept Hitler’s Germany and Stalin’s Russia,  Roosevelt maintained that every citizen must be guaranteed an additional set of “unalienable rights”, such as the right to adequate medical care, a decent home, and a good education among others. Sunstein also examines the international effects of this second bill and reveals beyond any doubt that those countries which incorporate its essence into their political landscape are currently far better off than its nation of origin. 

“The Making Of The Fittest: DNA And The Ultimate Forensic Record Of Evolution” By Sean B. Carroll

My Thoughts: Much ado has been made about Sean Caroll’s highly readable writing style and for good reason: in “The Making Of The Fittest”, he effortlessly guides the reader through such notoriously complex evolutionary topics as endosymbiosis, evo- devo, and gene fossilization. Furthermore, while most authors of such introductory popular science texts tend to shy away from examining their field’s most unusual constituents in the fear that their added complexity would thwart the progress of the reader’s emerging comprehension, Caroll highlights a plethora of bizarre and thoroughly engaging biological nonconformists to the delight and awe of the enthusiast and layman alike. Furthermore, in a scathing and unapologetic chapter towards the book’s conclusion that can only be described as a work of sheer brilliance, the licentious and decietful tactics of “Intelligent Design” proponents are brutally unmasked. Whether you’re an evolutionary devotee or a  curious non-expert, “The Making Of The Fittest” is sure to both enlighten and entertain.

“Why Beautiful People Have More Daughters: From Dating, Shopping, And Praying To Going To War And Becoming A Bilionaire–Two Evolutionary Psychologists Explain Why We Do What We Do” by Alan S. Miller & Satoshi Kanazawa

My Thoughts: Since it’s earliest exposure to the general public via Darwin’s “The Descent Of Man And Selection In Relation To Sex”, the field of evolutionary psychology (aka: “E.P.”) has maintained the dubious honor of arguably being the most controversial subdiscipline of any scientific domain for nearly a century and a half, having managed to simultaneously divide the general public and scientific community throughout this time.  In “Why Beautiful People Have More Daughters” Miller and Kanazawa do an impeccable job of forcing the reader to understand that E.P.’s routine political incorrectness is merely an examination of the way things are and not necessarily the way they ought to be. However, the authors are far more careless with regards to the headings given to various segments of discussion: for instance, their twin declarations that “human nature… stopped evolving 10,000 years ago” and “our brains are stuck in the stone age”, while not entirely devoid of truth, are misleading and frankly somewhat reckless. Fortunately, what Miller and Kanazawa lack in diplomacy is made up for in fairness: these men certainly aren’t shy about the limitations of evolutionary psychology despite their shared passion for the subject, and this willingness to acknowledge the young demesne’s imperfections alongside its achievements and contributions is most admirable.  

“A Confederacy Of Dunces” by John Kennedy Toole

My Thoughts: Although I don’t read fiction with the frequency of the average bibliophile, my comparatively limited exposure to the art form has nonetheless instilled within me a conviction that its most interesting characters are invariably those which the audience “loves to hate”. In this sense, I’ve yet to encounter a literary figure more captivating than “A Confederacy Of Dunces”s protagonist: one Ignatius J. Reily. While the routinely deplorable escapades of this verbose, malodorous, lackadaisical, delusional, pompous, gluttonous, discourteous, self-righteous, anachronistic, hideously clad, and morbidly obese medievalist should ideally repulse the reader,  the extravagant outlandishness with which he executes such mundane activities as job-hunting and moviegoing is positively endearing. While Reily is unquestionably the novel’s star attraction, Toole’s supporting cast is miraculously devoid of virtually any character which could be truthfully cited as “stereotypical”, and these eccentrics bounce flawlessly bounce off each other to create a beautifully unorthodox plot beneath this satirical masterpiece.

“Four Reasonable Men: Marcus Aurelius, John Stuart Mill, Ernest Renan, Henry Sidgwick” by Brand Blanshard

My Thoughts: In this delightfully original and (for the most part) brilliantly executed narrative, the reader is presented with a quartet of miniature biographies about four men whom he believes to have been “great for the same reason, the government of their lives by a quiet, habitual reasonableness.” In Blanshard’s view, reasonableness is defined as the possession of such admirable (and, as Renan often noted in a secular sense, “Christlike”) qualities as discipline, restraint, fairness, tact, open-mindedness, and respect for one’s opponents. While “Four Reasonable Men” does an impeccable job of explaining why all of its subjects deserve to be cited as possessors of these most honorable traits,  it does harbor a tendency to make relatively bold declarations concerning each man’s character and values without adequately reinforcing these contentions. Fortunately, however, the offending passages are relatively rare and fail to detract from Blanshard’s ingenious approach to enriching life and addressing the ethical concerns of the human condition itself.

“A Sea Without Fish: Life In The Ordovician Sea Of The Cincinnati Region” by David L. Meyer & Richard Arnold Davis

My Thoughts: Despite my lifelong captivation with vertebrate paleontology, I must admit that the sister science of invertebrate paleontology isn’t nearly as engaging in my view. This fact largely stems from the latter discipline’s comparative disregard for functional morphology in favor of stratigraphy: while both are highly relevant fields to each study, I simply find the former to be immeasurably more interesting. Consequently, I had essentially assumed that “A Sea Without Fish” would conform to the general trend of emphasizing the geological aspects of its spineless subjects over their physiological and ecological makeup. Thankfully, I was pleasantly surprised, for Meyer and Davis have balanced both topics seamlessly to provide a thorough and captivating analysis of the Cincinnati region’s world-famous Ordovician denizens in what is perhaps the finest example of a regional paleontology book I’ve ever come across. Of particular interest are the book’s chapters concerning mollusks, echinoderms, and arthropods.

Rest assured, loyal readers: more scientific posts are on their way!

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Nectocaris Update

26 05 2010

Good tidings and well-wishes!

Last week, I leant some coverage to the bizarre little Burgess Shale creature Nectocaris pteryx. At the time, all of the publicly-available information about the species maintained that

A) Its known from but a single specimen.

B) Postcranially, Nectocaris was a sinuous, chordate-like creature.

However, shortly after my article was published, everyone’s favorite stuffed theropod pointed out that a pair of Burgess Shale scientists (The University Of Toronto’s Martin Smith & Jean-Bernard Caron) had argued that Nectocaris was, in fact, the earliest-known cephalopod and were working on a paper to this end. Evidently, the pair had stumbled upon NINETY-ONE additional specimens such as the one below:

That paper was released today, and the results have dramatically altered our perceptions of what this beast looked like. Ed Young of the brilliant blog “Not Exactly Rocket Science” has the scoop.

For those too lazy to click on the link to my earlier post, here’s a traditional reconstruction of Nectocaris as derived from the genus’ first and, for several decades, solitary specimen:

And here’s the updated reconstruction based on this wealth of newfound material:

I think it’s fairly obvious to say that this isn’t merely some miniscule alteration: it radically changes everything we thought we knew about this creature’s anatomy and phylogeny. To quote Mr. Young:

“Around four centimetres in length, Nectocaris had a soft, flattened, kite-shaped body with two fins running down its sides. Its small head was adorned with two long tentacles and two stalked eyes. Unlike the compound eyes that were common among Cambrian animals, probably had the camera-like structure that modern cephalopods use. From its neck protruded a flexible funnel, which opened into an internal cavity containing pairs of gills.

The funnel lay behind some of the earlier confusion about Nectocaris. In the original specimen, it was flattened so that it looked like a shield-like plate behind the eyes, reminscent of a crustacean’s body armour. The new specimens put paid to that interpretation. The structure is clearly a funnel, similar to those used by modern cephalopods. Nectocaris probably used it to swim the same way, giving it an extra boost of jet propulsion to complement the beating of its large fins.”

The homogeneous lack of shells throughout the newfound Nectocaris specimens have shattered the notion that cephalopods evolved from Monoplacophorans: an assertion which largely rested upon the fact that the earliest known representatives of this tentacled group had previously been the nautiloids. Evidently, the shells which graced several groups and species of subsequent (and current) cephalopods evolved independantly.

However, not every gap has been filled in assigning Nectocaris to this new role: none of the fossils appear to display the intimidating beak-like mouth and horny tongue (known scientifically as the ‘radula’) of squids, octopi, and their kin remains, as far as the authors can ascertain, absent from N. pteryx. The radula is of particular importance due to its presence in nearly every group of modern mollusks and has hence become a uniting feature.

Regardless of what Nectocaris’ true relations may be, this news provides yet another example of how fossilized species with which the scientific community feels it’s somewhat familiar can drastically suprise its members almost instantaneously by way of new discoveries (or even, in some cases, a second trip through the archives).

A POINT TO CONSIDER: How much time will elapse before PZ Meyers jumps all over this story?





Yet Another Awesome British Science Show…

26 05 2010

Good tidings and well-wishes!

A YouTube acquaintance of mine recently sent me the following clip from the British Channel 4 program “Inside Nature’s Giants” which, as far as I can ascertain, is an intriguing exploration into the ecology, evolution, and comparative anatomy of some of the planet’s largest creatures. The video I’ve posted appears to be a collection of clips from a trio of episodes involving the modern giraffe, what I believe to be a Nile crocodile, and the asian elephant. Sadly, it looks like there’s no news of a DVD coming along anytime soon. Fortunately, however, there’s no shortage of available online clips.

WARNING: This footage involves a great deal of dissection and is therefore NOT for the squeamish and/or faint of heart!

NOTE: Dawkins’ assertion that “[Crocodiles] haven’t changed much in a very long time” is a gross and inaccurate oversimplification of crocodylian evolution… for more information, I’d reccomend tracking down a copy of this book.





A Slime Mold’s View Of Time

24 05 2010

Good tidings and well-wishes!

I’ve recently been reading John Tyler Bonner’s very intriguing, albeit imperfectly written (his writing style can, on occasion, be needlessly vague), book entitled “Why Size Matters: From Bacteria To Blue Whales” which, as the name suggests, analyzes the role of an organism’s size in it’s evolution, ecological niche, population density, and anatomy/physiology.  Dr. Bonner is perhaps best known for his expertise in the field of Slime Mold research, a fact which resulted in the following essay that first appeared in the Buddhist magazine Tricycle following a request from the magazine’s editorial staff just before the dawn of the 21st century. Although some of the prose contains a degree of anthropomorphism (which, given the non-scientific context, is excusable), I think that, overall, it nicely articulates just how ‘relative’ time often is in the scientific sense:

“Time From The Point Of View Of A Slime Mold”

Time and life are intertwined in so many different ways, something all biologists are acutely aware of. Consider a few extremes: a single cell bacterium may have its entire life cycle in half an hour, but a generation for an elephant takes 12 years and a giant sequoia 60 years. One reason I work with slime molds, which are soil amoebae that start off as single cells, and then come together to form a multicellular organism, is that their generations are short, so that if I start an experiment on Monday, I will know the result by Wednesday or Thursday. This kind of biological time–life cycle time–is at the middle of the time scale of living phenomena.

At the faster end of that scale is physiological time: how many beats does a heart have in a minute, or how long does it take to swerve the car in order to avoid a squirrel on the road. As with life cycles, these rapid living activities are greatly affected by size, so a huge elephant will have about 25 heartbeats per minute, while a tiny shrew’s heart goes at the amazing rate of over 600 beats every minute. The elephant will step to one side with slow deliberation compared with a small sparrow on the willow ledge with its lightning movements. We can combine the concept of the time required for a life cycle and the time required for rapid physiological processes in an interesting way. A shrew will live only a year or two, but an elephant will average 40 to 50 years; yet they have one thing in common: the total number of heartbeats they have in their whole lifetime will be approximately the same. So life for the small beast goes faster because its engine is racing along compared to the larger beast, and the total budgets for their actions are the same.

Evolutionary time is another time scale in the realm of life. Now we are no longer dealing with one generation, but with a great series of generations going way back in time to the beginning of life on earth. We are no longer dealing with minutes or a few scores of years, but with millions, and even billions of years. We find in the fossil record an era when all life consisted of cells, which later were followed by simple multicellular organisms, leading ultimately to all the great variety of animals and plants that we see on the earth today. This has been an exceedingly slow and exceedingly grand evolution that has taken up a vast quantity of time–so much so that it is difficult to comprehend the magnitude of geologic time. And we know that even these time spans are modest compared with those of the astronomer, who thinks in terms of light-years*.

So what does a biologist think of this second millennium? It is too short a time for major changes in evolution, but time enough for many generations. Every 1000 years will allow some 50 human generations, but the shrew will have a new generation each year, which means [some] 1000 each millennium. So for slime molds and shrews, the second millenium has meant waiting impatiently for a huge number of generations, while for elephants and ourselves–the wait barely tries our patience.

* [(I fully realize that a light-year is a unit of distance, and not time. However, the enormous amount of time required to travel between them preserves Bonner’s point.)]

The sheer magnitude of time with which paleontologists work on a daily basis is every bit as humbling and awe-inspiring as the vastness of space so eloquently celebrated by a host of passionate astronomers and astro-physicists throughout the ages from Issac Newton to Carl Sagan. 

But alas, I’ve said too much already! To those among my readers who study the field of long-vanished life, either professionally or as amateurs such as myself, I’d like to ask how this knowledge of deep time affects you outside the realm of scientific pursuits and during the course of day-to-day life.

May the fossil record continue to enchant us all!





Burgess Shale Extravaganza: Canadia

21 05 2010

Good tidings and well-wishes!

I’ve saved the concluding entry in this week-long diagnosis of Burgess Shale weirdos for what I consider to be one of the most extravagant and yet under-appreciated denizens of this most paleontologically vital of fossiliferous congregations: the 3-centimeter annelid Canadia spinosa.

The bizarre, vaguely feather-shaped extensions of the creature’s anatomy as shown in the previous photograph are in fact an innumerable series of short, rigid bristles scientifically known as “setae”. More specifically, they can be classified as “notosetae”: these are setae which are rooted in an animal’s dorsal lobes. These rather “showy” contraptions cover essentially the entire dorsal surface of Canadia. In famed Burgess paleontologist Simon Conway Morris’ book entitled “The Crucible Of Creation: The Burgess Shale And The Rise Of Animals” (which was largely written from the perspective of a time-traveling scientific research team, hence the heavy editing I’ve provided), he writes:

“Each bundle [of notosetae overlaps] the one behind it, so as to give a tile-like covering to the upper surface of the body. There can be little doubt that this entire arrangement [was] primarily protective. The neuropodia [or “ventral branches”], in contrast, are much more lobe-like and strongly muscular. Each neuropodia bears a prominent podium of [setae], and it is on these structures that [the creature walked]…[theoretically] by a series of locomotory waves passing along the neuropodia. By precise coordination each neuropodium is first placed on the seabed and then pushed back so that the [notosetae] act as levers to push the animal forwards. Finally, at the end of the stroke the neuropodium lifts the [setae] clear of the sediment and swings them forward in preparation for the next shove against the sea floor.”

In addition to hypothetically providing a degree of protection, the notosetae may have enabled Canadia to swim were they rhythmically beaten while cruising above the sea floor.

Canadia‘s gut was straight and was capable of anteriorly extending from the main body to form a proboscis of sorts. Along with the frequent presence of sediment in the beast’s gut, this digestive setup has given rise to the hypothesis that Canadia was a detrivore. The function of the anterior pair of tentacles is unknown, though they likely assisted the animal’s sensory capabilities.

I’ll close this article with an intriguing idea championed by Conway Morris’ aforementioned volume: that Canadia may in fact be that most elusive of Cambrian fauna: a relative of WiwaxiaWere this true, it would greatly disambiguate the spiny little eccentric’s incomparably vague phylogeny. Consider the following passage:

“When the [setae] is placed under the microscope, it is seen to have a microstructure very similar to that observed in Wiwaxia. Evidently there is some evolutionary connection between Canadia and Wiwaxia.”

Furthermore, Conway Morris notes that the ventrally-situated gills of Canadia strongly resemble those of modern molluscs, which persuasively insinuates a kinship between the genus and the mollusca phylum as well. Hopefully, additional discoveries will yield a plethora of new information concerning this functional morphology, evolution, and taxonomic affiliations of most engaging organism.

May the fossil record continue to enchant us all!





Burgess Shale Extravaganza: Aysheaia

20 05 2010

Good tidings and well-wishes!

Although many self-described “hard-core” scientists refuse to acknowledge it, popular culture exerts an appreciable influence upon virtually every discipline of science imaginable. Dinosaurian afficionados are well aware of Gary Larson’s “The Far Side” leading to the anatomical term “thagomizer” (which, for those ill-versed in paleo-jargon, describes the unique  spike arrangements on the tails of stegosaurs), guitarist Mark Knopfler’s namesake theropod Masiakasaurus knopfleri, and, of course, the “Harry Potter”-inspired pachycephalosaur Dracorex hogwartsia.

Dinosaurs, however popular, are far from the sole examples of this trend, as evidenced by the Burgess Shale denizen Aysheaia sp. whose genus name derives from the Ayesha mountain peak which, in turn, was named for Aysha: a sorceress and the “title” character of Rider Haggard’s 1905 novel “She: A History Of Adventure”. As is the case with its literary namesake, the simultaneously “alien” and “familiar” appearance of the two-inch Aysheaia is, as with many Burgess Shale residents, quite spell-binding (how’s that for a labored segue?).

According to Stephen Jay Gould’s “Wonderful Life”:

Aysheaia has an annulated, cylindrical trunk, with ten pairs of annulated limbs attached at the sides near the lower surface and pointing down, presumably for use in locomotion. The anterior end is not separated as a distinct head. It bears a single pair of appendages, much like the others in form and annulation but attatched higher on the sides and pointing laterally. The terminal mouth (smack in the middle of the front surface) is surrounded by six or seven papillae. The head appendages bear three spinelike branches at their tip, and three additional spines along the anterior margin. The body limbs end in a blunt tip carrying a group of up to seven tiny, curved claws. Larger spines emerge from the limbs themselves. These spines are absent on the first pair, point forward on pairs 2-8, and backward on 9-10.”

It should be noted that the limb-like appendages of Aysheaia are not true legs but can best be termed “lobopods”. Despite the fact that each lobopod is divided into a series of transverse rings, these are not to be mistaken for the series of joints which compose the legs of arthropods. In life, these lobopods would have contained a thick, muscular core surrounded by a fluid-filled cavity. This setup would have served as a hydraulic pump of sorts designed to enable locomotion.

Interestingly, a large percentage of Aysheaia specimens are found in association with the remains of sponges–an essentially nonexistent occurence elsewhere within the Burgess faunal roster. This has given rise to the well-accepted hypothesis that Aysheaia may have fed and dwelt upon these most primitive of animals. The idea is granted additional credibility when one considers the uselessness that the animal’s many claws would have likely served on the muddy floor of the basin. However, these spikes could have easily been employed for the purposes of scaling sponge colonies. Furthermore, it’s logical to conclude that Aysheaia‘s preserved anatomy insinuates no recognizable form of defense: a dire predicament which could have easily been averted were the creature to seek refuge within its (theoretical) spongy home.

As for Aysheaia‘s phylogenetic relationships, most paleontologists acknowledge that the beast bears a strong overall resemblance to the modern velvet worms (phylum Onychophora), although whether or not the genera should be considered a member of their phylum remains the subject of debate.

May the fossil record continue to enchant us all!





Burgess Shale Extravaganza: Amiskwia

20 05 2010

Good tidings and well-wishes!

NOTE: Contrary to the assertions of WordPress, this article was in fact posted on the 19th.

The soft bodied and rather delicately-built Amiskwia sagittiformis is a superb example of the conflict which often arises when a fossil is subjected to exceptional preservation and a debatable amount of deformity. The soft composition and meager proportions of Amiskwia and its kin prevent their fossil record from becoming remotely extensive. Hence, we may never know the degree to which geologic forces have altered the appearance of this superficially worm-like animal. Nonetheless, enough information has been gathered to make a few tentative educated guesses concerning its lifestyle and possible taxonomic affiliations.

Though the statement may sound comical, at a full inch in length, Amiskwia was a comparatively large inhabitant of the Burgess Shale and the elder Maotianshan Shales . This considerable size appears to have come at the expense of abundance, with a mere eighteen specimens of this peculiar genus having been found in the former deposit as of this writing.

Amiskwia‘s entire body is dorso-ventrally compressed. Its head sports a pair of ventrally-situated tentacles, just behind and between which lies an ovular mouth. Though the creature’s “trunk” is unsegmented, it does contain a pair of lateral fins which are unsupported by any sort of stiffening device: the same is true for the caudal fin which comprises the beast’s tail. The trunk and caudal regions of Amiskwia‘s anatomy appear to have been quite muscular: a piece of evidence which supports the hypothesis that Amiskwia may have been a pelagic (free-swimming) organism, which would also help to explain its aforementioned rarity in the formerly muddy Burgess basin.

Intriguingly, the internal anatomy of Amiskwia is also relatively well preserved, as partially displayed by the following fossil specimen:

According to the Smithsonian Institution’s official page on the species:

“Note that in the fossil preparation the head shows a highly reflective area (cerebral ganglia? [aka: the bilobed ‘brain’ of many modern worms and arthropods])… The broad light area running along the trunk is the gut, while the narrow linear structures along the trunk may be traces of blood vessels and a nerve cord.”

 

Note the rather conspicuous pair of bulb-like organs in the head of this Amiskwia reconstruction: this is the artist's depiction of its cerebral ganglia.

The phylogenetic relationships of Amiskwia are a matter of some debate. However, the general consensus amongst Cambrian paleontologists is that while the genus exhibits characteristics akin to those of the chaetognatha and nemertea. it cannot be scientifically accomodated by either group.

May the fossil record continue to enchant us all!