Featured Spotlight: Elomeryx

10 10 2010

Good tidings and well-wishes and once again, I must apologize for my lengthy, school-induced posting drought!

As a result of my earlier posts on Coryphodon, Pezosiren, and Estemmenosuchus, it’s fair to say TTT has acquired a history of discussing semi-aquatic and superficially hippo-like animals (though Brian’s blog certainly has mine bested in this field). To shake things up just a wee bit for this particular ‘spotlight’, I’d like to shed some coverage upon Elomeryx sp., an animal which, shockingly, may actually be related to modern hippos! However, as we shall see, this particular creature is arguably much better known for its theoretical kinship with another group of contemporary mammals: the Cetacea (which is hardly surprising, for, as I’ve argued earlier, cetaceans are rapidly becoming the “nonavian theropods” of paleo-mammology).

A reconstruction originally compiled by Philip Gingerich wherein Elomeryx stands in as a model of the earliest artiodactylian ancestors of archaic whales.

Elomeryx is the oldest known constituent of the Anthracotheriidae, a family which, as defined by the genus’ arrival, first evolved in the Mid-Eocene of Eurasia. The group subsequently spread throughout both of the region’s continents along with Africa and, to a lesser extent, North America before its youngest known member, Merycopotomas, went extinct during the late Pliocene. Presumably, the group’s decline in the old world is the result of the spread of primitive hippos whilst their limited tenure in the western hemisphere has often been attributed to a lack of diversity and widespread alterations in habitat.

Elomeryx reconstruction

The Anthracotheriidae is divided into three subfamilies, the Anthracotheriinae, the Microbunodontinae, and the Bothriodontinae, with Elomeryx itself hailing from the latter assemblage. According to Donald G. Kron and Earl Manning, this group is defined on the basis of the following characteristics: “[C]anine tusklike; upper molar mesostyles fully invaded by transverse valley; mesostyle not forming a fully developed cusp in consequence; and ectoloph completely W-shaped.”  

E. crispus skull hailing from Southwestern France.

(Do check out this paper for more details on the above image)

Discovered by Othneil Charles Marsh during the famed “bone wars” of the late nineteenth century (on a side note, I’d most heartily recommend Mark Jaffe’s excellent book on the subject to those interested in this fascinating period of U.S. paleontology), Elomeryx is noteworthy for, among other things, its sexual dimorphism (though its hardly the only Anthracothere to exhibit such diversity in this regard): male specimens sport serrated posterior edges on their upper canines. Alongside this feature, the genus may be recognized by its short rostrum, five-cusped molars, looplike mesostyle, a diestemata-free premolar row, and the presence of accessory cusps on premolars in derived species. Intriguingly, some authors maintain that Elomeryx is paraphyletic, an assertion whose verification will require a more intensive study of North American specimens. The genus is generally considered to have been a consumer of freshwater vegetation on the basis 0f its dental morphology, though it should be noted that its relative lack of specializations render any effort to precisely reconstruct its lifestyle elusive at best.

Earlier, I treaded lightly whilst discussing the phylogenetic affiliations of the Anthracotheriidae. This discretion stems from the fact that these relations have become the focal point of considerable controversy in recent years. While essentially everyone is in agreement over the well-evidenced notion that hippos are the closest living relatives of cetaceans, the precise nature of this linkage is hardly “crystal clear”. The fact that the first Archaeocetes predate Elomeryx in the fossil record all but rules out the possibility that Anthracotheres could have given rise to these earliest of whales, depending, of course, on whether or not future fossil evidence will contradict this assertion. The situation is complicated further by a recent paper which argues that the Anthracotheriidae is akin to the Entelodontoidea and the enigmatic Andrewsarchus which, together, form the proposed Cetacodontamorpha lineage which, according to Michelle Spaulding, Maureen O’Leary, and John Gatesy, is defined as the “Cetancodonta plus all extinct taxa more closely related to extant members of Cetancodonta than to any other living species”.

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A Glittering Ichthyosaur

24 09 2010

Good tidings and well-wishes!

It’s fair to say that TTT has been a bit of a “ghost blog” for a few weeks now: a result of my crazed academic schedule to which I’ve yet to fully grow accustomed. As if this weren’t enough, two of my brand new courses are conducting their mid-term examinations early next week, a fact which has forced the hostile takeover of virtually every ounce of free time I’ve managed to scrounge up lately by excessive studying.

Ah, but misery loves company. The fact that mid-terms are a thorn homogeneously spread throughout the sides of undergraduates across the nation affords me the opportunity to occasionally relieve myself from my own scholarly preparations in order to assist my friends in executing theirs. One of my room-mates is an English major whose particular topical line-up for this examination period involves developing an acute knowledge of Joseph Conrad’s melancholy and profoundly disturbing “Heart Of Darkness”, which I, myself had read a few years ago (the horror!). Whilst quizzing him on the book’s finer points via “cliffsnotes”, I noticed that one of the words defined in the volume’s glossary was “Ichthyosaurus“. My curiosity piqued, I scourged the novel for the reference to this most famous of fossilized marine reptiles, leading me to stumble upon the following passage:

“A deadened burst of mighty splashes had reached us from afar, as though an ichthyosaurus [sic] had been taking a bath of glitter in the great river.”

A large ichthyosaur meanders about the famed Crystal Palace Park in London. According to palaeos.com, the first-known ichthyosaurs and plesiosaurs "had a strong effect on the 19th century Victorian imagination".

 

Prehistoric reptiles are hardly unknown for their ability to tus make literary cameos, as evidenced by Mark Twain’s occasional dinosaur references to say nothing of Sir Arthur Conan Doyle’s groundbreaking masterpiece, “The Lost World”. 

Right, then: back to my bloody mathematical formulas!!!





The Jefferson Fossil Collection (Yes, THAT Jefferson…)

4 07 2009

Good tidings & well-wishes and, for all of my American readers, happy fourth of July!

I’ve always enjoyed reading about the American founding fathers (however, I’m certainly not the sort of person to canonize them) and the political environment which led to the birth of our nation. It therefore comes as no surprise that I devoured Paul Semonin’s excellent book entitled “American Monster: How The Nation’s First Prehistoric Creature Became A Symbol Of National Identity” and its accompanying website as soon as I was able to do so. Both chronicle the effects of early American paleontology (which chiefly concerned Mammut americanum and Megalonyx sp.) 0n several of the emerging country’s most influential revolutionaries such as George Washington and Benjamin Franklin. However, of these men, none were so smitten by paleontology than the author of “The Declaration Of Independence” himself and the man to whom this pyrotechnic holiday primarily owes its conception, Thomas Jefferson.

Jefferson famously asked Louis and Clark to be on the lookout for living mastodons at the onset of their journey (which was obviously a fruitless search, though they did manage to find a host of fossils from various beasts) and even stored several remains of these mysterious animals in the White House itself during his presidency.

The historic Academy of Natural Sciences has compiled a comprehensive and very readable guide to Jefferson’s paleontological collections and endeavors. What better way for a paleo-enthusiast to spend the fourth than reading up on something that’s both patriotic and paleontological? It beats shooting fireworks in my humble opinion (and it costs a lot less)…

May the fossil record (and those who’ve studied it) continue to enchant us all!