In 1900 the famous bone sharp Barnum Brown discovered the skeleton of a huge carnivorous dinosaur in Wyoming, and near its bones were a few fossilized bony plates. When H.F. Osborn described this creature as Dynamosaurus imperiosus he used this association to hypothesize that this predator was covered in armor, but as it turned out "Dynamosaurus" was really a representative of another new dinosaur Osborn named Tyrannosaurus rex. Osborn's famous tyrant showed no sign of being covered with armor, and the bony body covering turned out to belong to an ankylosaur. The prospect of an armor-clad prehistoric killing machine, tantalizing as it was, could not be upheld. (Osborn described "Dynamosaurus" and Tyrannosaurus in the same paper, and when he found that the two were synonymous he had the choice of which name would represent the animal. He chose Tyrannosaurus, which I think was the better of the two names [Thanks to Chris for the correction].)
The problem of misplaced armor confounded paleontologists on at least one other occasion, though. While skimming H.N. Hutchinson's Creatures of Other Days I noticed a curious footnote that said Basilosaurus had been covered in armor. This discovery was attributed to a report by "Professor Dames, of Berlin" and I was fortunate enough to be able to track down the appropriate Natural Science article.
The article itself was not by Dames but a brief review on "Armoured Whales" citing Dames' 1893 paper in Palaontologische Abhandlungen. The author of the note reported;
Not the least noteworthy portion of the Professor's [Dames] memoir is the one in which he describes certain bony plates found in association with Zeuglodont remains, which are believed to indicate the presence of a dorsal bony dermal armour. That such an armour may have existed in primitive Cetaceans, is rendered the more probable by Dr. Kukenthal's recent discovery of the vestiges of such a structure in the skin of the existing Phocana (Neomeris) phocanoides.
Possibly the ancient Cetaceans were more exposed to such attacks as the one above described by Mr. Lydekker, and, for this reason, required greater protection. It is well known that the early forms of many groups of animals were provided with some such armour, or evolved some equally adequate means of defence. ... The dermal armour of these ancestral Cetaceans may have been a secondarily-acquired character, from which no particular argument as to their relationships can be drawn.
[The nomenclature has changed since this paper was published. "Zeuglodon" is a synonym of Basilosaurus and "Phocana phocanoides", as far as I have been able to discern, is known today as the finless porpoise Neophocaena phocaeniodes (see Lydekker's discussion below). I have been unable to find any recent discussion of living cetaceans having any kind of armor.]
This discovery spurred debate about why ancient whales had been covered in armor and this new fact appeared in many discussions of Basilosaurus. The most detailed examination of the subject I was able to find was undertaken by Richard Lydekker in a 1901 Nature article (reprinted in Mostly Mammals). He wrote that Basilosaurus was at least partially covered by "a bony armor as solid as that of the giant extinct relatives of the modern armadillos," the glyptodontids of ancient South America. If armadillos and their extinct relatives were armor-plated, why not whale ancestors? Citing "Dr. O. Abel" Lydekker laid out the new proposed pattern for whale evolution;
In their earliest stage of development the toothed whales were fully armoured. The object of the armour was as a defence against enemies, such as sharks, such an armour being also very valuable to animals exposed lo the force of a strong surf on rocky shores. As the creatures took more and more to an aquatic life, the acquisition of greater speed would be of greater value to them, and this would be accomplished by diminishing the specific gravity and friction of the body, the shortening of the extremities and the development of a caudal fin to serve as the sole instrument of locomotion. Accordingly the armour would very soon be lost by the pelagic cetaceans in order to diminish friction and lighten the specific gravity. Only among certain types, which diverged at an early epoch from the ancestral stock and took to a fluviatile or estuarine life, did vestiges of the armour persist, while the dorsal fin remained undeveloped (Neophocaena).
[It is also worth noting that Lydekker ends his article by stating "In conclusion, it may be mentioned that modern investigations tend to connect the ancestral toothed whales with the Carnivora, and in no wise support Sir William Flower's favourite idea that these cetaceans trace their descent from early Ungulates." I will come back to Flower's interesting hypothesis at some other time.]
From embryology to fossils, the evidence seemed clear that whales had been armored for at least some part of their evolution. The question was whether they had evolved from armored terrestrial ancestors or whether armor was an adaptation to life in the sea. In his 1921 review of cetaceans, for example, Herluf Winge cited advocates of both views but did not provide a definitive answer.
Not everyone was so sure that Basilosaurus was an armored whale, though. In 1886, several years before Dames published his paper, the paleontologist A.S. Woodward noted that fragments of ancient leatherback turtle shell had been found with a Basilosaurus skeleton and led to the false impression that the armor belonged to the whale. Of these fragments Woodward said "Such remains, of course, are of little or no value from an anatomical point of view, and are merely sufficient to indicate the presence of Leathery Turtles in the Eocene seas." Lydekker knew of Woodward's paper (he made passing reference to it in his Nature article) but rejected his analysis.
The paleontologist F.A. Lucas was not so subtle. Frustrated by the popularity of an idea he thought had no basis Lucas blasted the concept of an armored Basilosaurus in a 1904 article that appeared in Science;
There is such a determined effort nowadays to derive the whales from armored ancestors and to foist a shield and buckler upon Zeuglodon [Basilosaurus] that it requires some courage to suggest that at present there is no good evidence that either of these theories is correct.
The supposed armor plates were only found alongside one skeleton and even then there were far too few plates to adequately protect it from attack (Lucas quipped that it would be better to call it a "mail-clad" animal). Likewise, Lucas stated that Basilosaurus was far too specialized to be ancestral to any living whales, thus making it irrelevant to any "armor" living species might or might not have.
With the exception of Winge's 1921 article and a encyclopedia entry from 1920, the question of armored archaeocetes appears to have been dropped at around the time Lucas published his critique. The only figures of the armor in question were in Abel's work, a paper I could not find, and quick search of the literature from 1920 to the present did not provide any new work on this subject. Even so, I had never before heard of the hypothesis that ancient whales were covered in a coat of armor, and I hope this forgotten piece of science history receives further attention from more able scholars.
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This is really neat, I'd never heard of this either.
I've been doing some volunteer work at the geo dep here at the Uni of Otago NZ on some Oligocene Squalodon's (shark toothed dolphins, if you've never heard of them). So been doing my background on later Whale evolution, which ties to this ever so slightly as New Zealand has the last known member of the Basilosauridaes (not armoured of course though ;p)
Although I've read quite a lot about archaeocetes in general, and Basilosaurus in particular, I had never heard about the controversy about the (now discredited) armor on Basilosaurus. I guess this is a good cautionary tale about being careful about drawing conclusions. Aside from not knowing why it would need it (being the biggest whale of it's time, if I'm not mistaken) aesthetically speaking, it just looks better without it! And by the way, even though I'm not crazy about the paleontological rule that the first name should always have priority (because you end up with names like "Basilosaurus") I'm glad that Osborn first used, and so had to keep the name "Tyrannosaurus rex" for his Cretaceous theropod, because "Dynamosaurus imperiosus" just doesn't have the same ring to it!
Sorry, this is wrong. Though often referred to, page priority doesn't actually have any standing under the ICZN. The rule is that if two names published in the same paper are later recognised as synonymous, the author who first recognises the synonymy gets to choose which of the names should be used, and all later authors have to follow their choice. Osborn named Tyrannosaurus and Dynamosaurus in 1905, and established their synonymy (and the use of Tyrannosaurus rather than Dynamosaurus) only a year later in 1906.
(Now that that's gotten that bugbear out of the way...)
So, DOES Neophocaena have anything suggestive of (vestigial?) armor? Or is that the result of another confusion?
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I've long been puzzled by how you're supposed to homologize Cetacean teeth: the drawing of a Zeuglodon skull at the top (hey, it was still called Zeuglodon in the first book about whales I ever saw: "Whales," by Herbert S. Zim, a children's book from no later than the very early 1950s) at least helpfully shows the suture between the maxilla and the premaxilla. So, for this species, if the drawing is of a typical skull, the reasoning seems to be that the upper canine is the first maxillary tooth, you correlate uppers and lowers by occlusal relations. And, I guess, distinguish premolars from molars by counting and referring to the standard placental dental formula. Or are there enough Z... (O.k., o.k, I give in) Basilosaurus juveniles known to allow premolars and molars to be distinguished by their successional histories?
Chris; Thanks for the correction. You know more about the rules of taxonomy than I do, and I had always heard that the Tyrannosaurus/Dynamosaurus issue had to do with which name was published first.
Allen; Like I wrote in the post I haven't been able to find anything about armor on living cetaceans. Lydekker, in particular, mentioned structures in the "integument" of a few other whales near the base of the dorsal fin, but it seems likely that these structures (whatever they were) were mistaken for something else.
Allen; I'm not sure how many (if any) Basilosaurus juveniles are known. It seems to be one of those genera where there are so many fossils from so many locations that it's hard to keep track of the available material. Like you inferred from the diagram, using sutures, occlusion, and the placental dental formula together seem to be the best way to determine what's what. This actually makes me want to take another look at Aetiocetus and Janjucetus, which are more homodont (if I recall correctly).
Oops! I guess I messed up too! I Should have known better than to believe everything I read. I thought the first name always had priority (although it was hard to reconcile this supposed rule with my observation that the names of fossil animals were changed fairly often.) Like you, I still favor "T.rex" over "D.imperiosus", and I wish Harlan had realized he was dealing with a fossil whale before naming it "king Lizard". Oh well, human beings are fallible, and the process isn't perfect!
About homologizing whale teeth...
I think I've already embarrassed myself on the WWWeb about this, saying silly things in the comments on something during Darren's "Fricking Weird Cetacean Skull" week on Tetrapod Zoology. (I'd have to go back to see what I said, and how I was corrected: I don't recall the details.) I ***think*** I remember that "placental dental formula" breaks down with at least one toothed Mysticete: more than eleven teeth.
...
Given that modern toothed cetaceans are both homodont and monophyodont (I think they are monophyodont, but I guess the source I read that in is pretty old...), AND can have way over the standard placental number of teeth: does the premolar/molar distinction make sense with them?
Neophocaena has a patch of bumpy structures (variously described as "denticles", "tubercles" or "small wart-like excresences" along the dorsal margin. You can *sort* of see them in this picture. The functional significance of these structures appears to be contentious (various web sources propose sensory or hydrodynamic significance). Perhaps the most interesting functional hypothesis is presented in the reference below (which I haven't read, but the title seems to say it all). At any rate, I haven't seen anyone describe these as "armour" and they don't seem to be ossified as far as I can tell.
Pilleri G, Peixun C. 1979. How the finless porpoise (Neophocaena asiaeorientalis) carries its calves on its back, and the function of the denticulated area of skin, as
observed in the Changjiang River, China. Invest Cetacea 10:105â110.
I have questions about evolution. There is no question that micro evolution takes place as I can see it, i.e. Galapagos finches, etc. Further, there is plenty of evidence of species evolving into distinct sub-species.
However, there is no evidence of inter-species evolution that I'm aware of. That is, of one species evolving into another. Also, I'm troubled that we haven't found any "initermediaries" in the fossil record. Species just seem to appear intact and fully evolved. This seems consisten with a Creator to me.
I'm certainly a seeker, but I'm not a Bible thumper or an advocate of the Earth being 6k years old, etc. In fact, I haven't accepted the divinty of Christ. However, I see evolutionists making pretty big leaps of faith as to evolution. Just as big, if not bigger, leaps of faith than religious people. Am I mistaken? Do you have reservations that at least some of evolutionary theory being wrong?
Thanks for all serious, thoughtful responses.
Tom
P.S. I'd be interested in any books you could recommend. Keep in mind that I'm not a scientist, though. Thanks.
Great post! Heuvelmans discussed this theory in his 1968 'In the Wake of the Sea-Serpents' and suggested that his "many finned" and "many humped" animals were armored archaeocetes. He notes that the armor found near Basilosaurus was from a tortoise and the tubercles on the finless porpoise are thickened epidermis - but goes on to state that the theory is "still fairly strong" because the Miocene Delphinopsis freyeri from Croatia was allegedly covered in bony tubercles! It has been suggested that the "armor" is a mineral secretion of some sort.
Tom; A response to your comment could be a book by itself, but I will do what I can here.
The first problem has to do with what you mean by "inter-species evolution." This, to my ears, sounds like speciation (the establishment of a new species) which has been observed many times. This is the evolution of a new species from a population of an already established stocked (i.e. evolution).
If I'm right, though, what you're looking for is a transitional series showing how aquatic whales evolved from terrestrial ancestors or how birds evolved from dinosaurs. The good news for you is that there are lots of transitional fossils! (Human evolution, especially, contains a rich record of transitional forms.) There are "fishapods" like Tiktaalik that show how limbs evolved while our distant ancestors still lived in swamps, feathered dinosaurs that show how many "bird" characteristics appeared in them first, and fossil whales adapted to life at the water's edge. (And that's just for starters.) The claim that there are no transitional fossils was one of the first charges leveled at Darwin's theory of evolution by natural selection, but it has been thoroughly refuted by fossil evidence. Even better, there are probably even more amazing fossils awaiting discovery.
Evolutionary theory does not require faith. It lives or dies by the evidence. It is not something to be believed in but supported by rigorous investigation. Some parts of evolutionary theory might change (in terms of the importance of certain mechanisms, for example) but I have seen no good evidence that would lead me to doubt that evolution is the best idea to help us understand the history of life on earth.
Like I said, the questions you raise could give rise to an entire book and I definitely recommend that you poke around the TalkOrigins website that I have linked to. In terms of books, none of the books presently on the market is perfect but here are a few good places to start if you're interested;
Evolution: What the fossils say and why it matters by Donald Prothero
Why Evolution is True by Jerry Coyne
Evolution by Douglas Futuyma (this is a textbook, but is a great source of information)
Darwin by Adrian Desmond and James Moore (a great biography of Darwin. Also check out Janet Browne's two biographical volumes.)
I'd be happy to answer any specific questions you have Tom, but the best advice I can give you is to really dive into the literature. Don't just read the books I listed above; find others that match your areas of interest more closely and read them carefully. There's no one book that can tell you everything you would want to know about evolution, but there is a lot of wonderful information out there.
Holy cow, I love the internet. Came here from Insty's link, read the comments, and saw Allen mention a book by Herbert S. Zim.
My grade school in San Antonio, St. Anthony's, had a bunch of science books by him in their little library, and I think I devoured them all. And I don't think I'd thought about them in probably 30 years at least. Wonderful books to get a kid interested in science.
Laelaps: Thanks for your thoughtful response. I'll start reading immediately!
Tom
I own a half-technical tome, written by Hans Petzsch in 1969, that still claims that there is embryological evidence for armour in porpoises, and that this is a relic of the armour of the archeoceti. Obviously, the armour hypothesis took a long time to die.
> Heuvelmans discussed this theory in his 1968 'In the
> Wake of the Sea-Serpents'
He also suggested, in his 1959 'On the track of unknown animals', that some of the armoured or scaly aquatic or semi-aquatic cryptids of South America were not reptilians or xenarthans, but rather late-surviving archeoceti.
"Dr. O. Abel" is of course Othenio Abel, the inventor of the word "paleobiology". They actually built a wall between the Paleontological Institute and the Paleobiological Institute of the University of Vienna as a result.
(The building no longer exists, though, and the institutes have been fused back together.)
Hello,
I don't have so much clear if the hipoppotamidae hipothesys (i mean that ceatceans and hipoppotamidae are sisters group), is accepted or not.
As I know Raoellidae (Indohyus) is the sister group (Thewissen, 2009) of cetaceans. But it depends on waht kind of article you read.
I need some help. Maybe the mistery don't have a solution yet?
Thank you very much.