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Tales from the Cryptozoologicon: Megalodon!

The views expressed are those of the author and are not necessarily those of Scientific American.


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Cropped version of John Conway's Megalodon image (scroll down for full version). From the soon-to-be-published Cryptozoologicon.

The other day I showcased some art and text from the upcoming Cryptozoologicon, a book currently being put together by John Conway, C. M. Kosemen and myself and scheduled to appear later this year. Today I want to do the same thing.

This time, we’re going to look at the section on Megalodon, the Megatooth shark. My, how timely! (read on to see why). Sharks aren’t tetrapods (and hence aren’t ordinarily part of the Tet Zoo remit) but, what the hey, I’ve broken the rules before, I’ll break them again here.

Hello there, Megalodon!

The seas are full of monsters. Or, they are according to some of the cryptozoological literature, anyway. As if numerous giant, as-yet-undiscovered marine mammals and reptiles and absurdly super-sized cephalopods aren’t enough, cryptozoologists have also advocated the possibility that Carcharocles megalodon – popularly dubbed Megalodon or the Megatooth shark – is not just known from the fossil record, but that it might also survive to the present. Megatooth sharks are, unsurprisingly, known almost entirely from their enormous teeth, the largest specimens of which are an incredible 16.8 cm long. Vertebral centra of Megatooth sharks are known in addition to teeth, but that’s it, and – unsurprisingly – there has been much tendency to over-estimate the size of this giant. A total conservative length of approximately 15.9 m was extrapolated by Gottfried et al. (1996) but they also calculated total lengths of as much as 20 m for some individuals. These authors also suggested that C. megalodon had a deeper, blockier skull than the Great white shark Carcharodon carcharias.

Extrapolated sizes for Megalodon (maximum and conservative), compared with Whale shark and Great white. Good ol' Pioneer Dork for scale. Image by Scarlet23, licensed under Creative Commons Attribution-Share Alike 3.0 Unported license.

While C. megalodon is often imagined to be a giant version of the modern Great white, it may only be distantly related to it. In fact, some experts allocate these sharks to entirely different sections of the shark family tree and at least three different technical names are used for C. megalodon (Carcharocles megalodon, Carcharodon megalodon and Megaselachus megalodon). Regardless, good evidence shows that Megalodon was ecologically similar to the Great white, albeit much larger and more powerful.

Dean's famously over-sized jaw reconstruction of Megalodon from 1909. He estimated the shark's total length to be 30 m! Image in public domain.

Bite marks preserved on bones show that Megatooth sharks fed regularly on dolphins and baleen whales, though it remains unknown whether the bite marks we know of represent scavenging or the hunting of live cetaceans. Megatooth shark teeth are frequently found in areas where the remains of baleen whales are common (Purdy 1996), and both shared the same habitat.

So far as we can tell from the fossil record, C. megalodon died out some time during the early part of the Pleistocene, presumably as cooling conditions reduced its preferred habitat [UPDATE: be sure to read comment # 6 below. A Pleistocene extinction date may be too recent!]. And here we come to the cryptozoological case for Megalodon survival: the sort of thing discussed in various popular books and magazine articles about mystery creatures (Shuker 1991, 1995, 1997). Alleged Megalodon survival was examined by Roesch (1998) who basically concluded that there is no reason to take alleged Megalodon survival at all seriously. We agree with his conclusions.

A very small number of stories and alleged eyewitness encounters essentially make up the core of the case for Megalodon survival. In the best known and most oft-repeated, Australian naturalist David Stead described a tale related to him in 1918 by Australian crayfish fishermen in which a gargantuan and ghostly-white shark, perhaps 90 m long, emerged from the deep to take their crayfish pots, mooring lines and whatever else was attached. This story has sometimes been taken semi-seriously, partly because Stead (a reputable and respected writer and researcher, greatly experienced in ichthyology) explained the reliable nature of his (anonymous) sources. Alas, a fishermens’ tale about a white monster shark that eats crayfish pots is hardly a reputable source and the account is an entertaining anecdote that we cannot regard as evidence of any sort.

There are various terrible images online that show scaled-up white sharks close to boats, grabbing surfers and so on. Here's one of the least terrible of them.

Two other giant shark sightings claimed to be possible Megalodon sightings are clearly poor descriptions of Whale sharks Rhincodon typus. There’s also a story from the 1960s (recounted in a popular 1978 book) about a giant white shark, longer than 80 m, spoken of by a ship’s anonymous crew. So, we’re left with stories: scary stories of the sort that seafarers enjoy telling other people when back on land. Indeed, the case for Megalodon’s survival is so weak that it isn’t really “a case”.

Megalodon survival is also supposedly supported by the discovery of teeth that are not fossilised or are supposedly coated in such a thin layer of manganese dioxide that they must surely be young, in geological terms. In fact, the teeth (the most famous of which were dredged up by the Challenger expedition of the 1870s) have been misinterpreted and there’s no reason to think that they’re geologically young, let alone modern (Roesch 1998).

The speculative part

What, now, of our speculative parallel universe, where all the cryptids are real and megatooth sharks still swim the oceans? Again, it would be difficult to say anything speculative about Megalodon that hasn’t already been said. In order that a giant, macropredatory, whale-eating shark might remain elusive and undocumented by biologists, it would have to be absurdly secretive, spending just about all of its time away from the surface, away from vessels, and away from the coastal regions where it would surely be discovered. It must, therefore, be a deepwater animal that specialises on prey that it can reliably encounter at depth, and it must have switched to this prey base some time since the Pliocene or start of the Pleistocene. [The brilliant image below shows a modern-day Megalodon, by John Conway. For the full-size version go here.]

Modern-day Megalodon, by John Conway. The boat might look familiar. From the soon-to-be-published Cryptozoologicon.

This evolutionary shift has occurred at breakneck speed: while a new, slower growth regime and occupation of an otherwise unexploited ecological niche have encouraged Megalodon to become substantially larger than the 20 m or so achieved by its ancestors, it has not yet become fully abyssal like other deepwater sharks and still visits the surface to eat crayfish pots and small fishing vessels on occasion. We would have to imagine the new, abyssal Megalodon – arguably different enough to warrant classification as the new species Carcharocles modernicus – to haunt deepsea canyons and places where whales and elephant seals and so on are regular visitors.

Previously, it was Mermaids. Discovery wins again… (read: loses)

Of course, our coverage here of Megalodon is extremely well timed since Discovery have just screened a notorious pseudo-documentary in which they seemingly try and trick naïve viewers into thinking that Megalodon is still extant, and that there’s evidence for this possibility in the way of assorted photos and other lines of evidence [disclaimer: at the time of writing, I haven’t seen said TV show]. The idea that a once-reputable documentary-based TV channel might broadcast such a show is incredible, even in the wake of the two ridiculous mermaid shows screened by the same channel over the past few years.

So far I’ve heard nothing but dissatisfaction and anger directed at Discovery, with some people even demanding an apology. Remember that their Megalodon show isn’t presented as mere entertainment a la Sharknado, but as a documentary that’s screened adjacent to genuine documentaries about real sharks, their biology, their world, and their plight. It will surely be interpreted as real by a large percentage of its viewers. As shown (above) by this screen-grab from Discovery’s facebook page, people aren’t happy (at least, people who leave comments on the page… the disturbingly high number of ‘likes’ shows how popular such garbage is). If any of this energy can be converted to help benefit real sharks in the real world, we can be happy that something good has come of it.

Thanks to Cameron McCormick and Jason Brunet....

The Cryptozoologicon – by John Conway, C. M. Kosemen and Darren Naish – is due out later in 2013 and will be published by Irregular Books. Follow @IrregularBooks on twitter.

Refs – -

Gottfried, M. D., Compagno, L. J. V. & Bowman, S. C. 1996. Size and skeletal anatomy of the giant “megatooth” shark Carcharodon megalodon. In Klimley, A. P. & Ainley, D. G. (eds) Great White Sharks: The Biology of Carcharodon carcharias. Academic Press (San Diego), pp. 55-66.

Purdy, R. W. 1996. Paleoecology of fossil white sharks. In Klimley, A. P. & Ainley, D. G. (eds) Great White Sharks: The Biology of Carcharodon carcharias. Academic Press (San Diego), pp. 67-78.

Roesch, B. S. 1998. A critical evaluation of the supposed contemporary existence of Carcharodon megalodon. The Cryptozoology Review 3 (2), 14-24.

Shuker, K. P. N. 1991. The search for monster sharks. Fate 44 (3): 41-49.

- . 1995. In Search of Prehistoric Survivors. Blandford, London.

- . 1997. From Flying Toads to Snakes with Wings. Llewellyn Publications, St. Paul, Minnesota.

Darren Naish About the Author: Darren Naish is a science writer, technical editor and palaeozoologist (affiliated with the University of Southampton, UK). He mostly works on Cretaceous dinosaurs and pterosaurs but has an avid interest in all things tetrapod. His publications can be downloaded at darrennaish.wordpress.com. He has been blogging at Tetrapod Zoology since 2006. Check out the Tet Zoo podcast at tetzoo.com!

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The views expressed are those of the author and are not necessarily those of Scientific American.





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  1. 1. Mike from Ottawa 12:55 am 08/6/2013

    You’ve got to figure if megalodon were still around, it would have been the bane of the whaling industry and very well known. I mean, whaling was essentially chumming the waters with blue whales. At some point, a ship with a harpoon gun would have nailed one and had it brought aboard a factory ship for examination.

    Link to this
  2. 2. llewelly 1:02 am 08/6/2013

    I am looking at the “NOOOOOO” picture, and I am trying to use the ruler in it to estimate the height of the large blue plaid shirted primate on the far right.

    This primate seems to be in excess of 130 feet tall, quite a remarkable height for a primate, and I would like to know if anyone has any information on reports of similarly large primates, particularly any seen climbing tall buildings.

    Link to this
  3. 3. Heteromeles 1:06 am 08/6/2013

    Ah crivens! Not you too! At the very least, post the link to the Discovery Megalodon disaster so that I can post my dislike there too.

    I tuned in to the end of it, assuming it was a stupid but misguided semi-documentary, that they were fooling around if nothing else, and they’d come up dry like all good cryptid hunters do. Then they had that amazingly stupid final (and obviously staged scene, with camera shots all carefully angled and all to make it obvious it was staged, and I changed the channel so fast I almost broke the remote.

    Still, I AM disappointed this particular piece of foetid effluvia turned up here. Don’t tell me SciAm has joined in Discovery Channel’s descent into fictional irrelevance, and is forcing their bloggers to publicize this stuff.

    Link to this
  4. 4. Cameron McCormick 1:06 am 08/6/2013

    This should in no way be seen as an endorsement of extant Megatooth Sharks.

    Anyways, it’s interesting that large extant sharks are capable of some seriously impressive dives. Whale Sharks can dive to 1720 meters (Heuter et al. 2008). Basking sharks can go down to 1264 m (Gore et al. 2008) and stay 250–1000 m deep for 5 months (Skomal et al. 2009). Great White Sharks can go down to 1280 m (Last & Stevens 1994). Sleeper Sharks have been observed down to 2647 m (Benz et al. 2007). Bluntnose Sixgills have been recorded down to 2500 m (Ebert 2003). Since Whale Sharks appear to dive for thermoregulatory purposes (Thums et al. 2012), perhaps this speculative Megalodon species encountered something tasty and abundant on its dives and started to spend more and more time at great depths.

    Benz, G. et al. (2007) First record of a sleeper shark in the western Gulf of Mexico and comments on taxonomic uncertainty within Somniosus (Somniosus). Bulletin of Marine Science 80(2) 343–351.

    Ebert, D. (2003). The Sharks, Rays and Chimaeras of California.

    Gore, M. et al. (2008) Transatlantic migration and deep mid-ocean diving by basking shark. Biology Letters 4 395–398.

    Hueter R., et al. (2008). The graphical movements of whale sharks tagged with pop-up archival satellite tags off Quintana Roo, Mexico. IN: Second International Whale Shark Conference. Holbox, Mexico.

    Last, P. & Stevens, J. (1994) Sharks and rays of Australia

    Skomal, G. et al. (2009) Transequatorial Migrations by Basking Sharks in the Western Atlantic Ocean. Current Biology 19 1–4.

    Thums, M. et al. (2012) Evidence for behavioural thermoregulation by the world’s largest fish. J. R. Soc. Interface 20120477.

    Link to this
  5. 5. Dartian 1:19 am 08/6/2013

    Darren:
    The boat might look familiar.

    Yeah, but it needs to be bigger. ;)

    visits the surface to eat crayfish pots and small fishing vessels

    Could its dietary habits be summed up then by saying that it eats fish and ships?

    a deepwater animal that specialises on prey that it can reliably encounter at depth

    Slightly more seriously now: Giant squid sounds like an obvious food source. Squid are certainly abundant enough down there for sperm whales to be able to make a living by eating them.

    Link to this
  6. 6. Boesse 4:43 am 08/6/2013

    Pleistocene extinction of C. megalodon is quite a bit too young, in my opinion. I won’t yet comment on my in-prep research with Dana Ehret and Doug Long, but two previous studies have noted the position of the stratigraphically highest C. megalodon occurrences in two relatively well-sampled basins. In the Atlantic Coastal plain, the highest record of C. megalodon is from what used to be called Unit 2 of the Yorktown Formation, which is now the upper part of the Sunken Meadow Member (early Pliocene). The Rushmere and Moore House members of the Yorktown lack C. megalodon, but produce a healthy amount of other teeth, and given the intense focused collecting there I doubt a case could be made for collecting bias. Anyway, Ward (2008) suggested an early-middle Pliocene (~3-4 Ma) extinction. Another study by Stefano Marsili (2008) also indicated that C. megalodon teeth only occur in lower Pliocene and younger rocks in Italy, again in the 3-4 Ma ballpark. Anyway – there is MUCH more to be said, so stay tuned, something is in the pipe.

    Marsili, 2008. Systematic paleoecologic and paleobiogeographic analysis of the Plio-Pleistocene Mediterranean elasmobranch fauna. Atti Soc. tosc. Sci. nat., Mem., Serie A, 113 (2008):81-88

    Ward, Lauck, W. (2008). Synthesis of Paleontological and Stratigraphic Investigations at the Lee Creek Mine, Aurora, N.C. Virginia Museum of Natural History Special Publication 14:325-436.

    Link to this
  7. 7. altondooley 8:19 am 08/6/2013

    Following Boesse’s comment, on the U. S. Atlantic Coast C. megalodon teeth are abundant in the Sunken Meadow Member of the Yorktown Formation (lower Pliocene, c. 4.5 Ma), but have never been found above that unit, even though these units have been heavily collected for over a century. To be fair, there is a general drop in the abundance of vertebrates above the Sunken Meadow, but they don’t disappear entirely; there are still teeth from a number of extant shark taxa, and there are still occasional specimens of cetaceans, including relatively large taxa (Balaena, Balaenula, unidentified balaenopterids).

    Link to this
  8. 8. SWestfall 8:37 am 08/6/2013

    A lot of confusion exists about the exact size great whites of the modern variety can reach. That’s because the historical name for the great white, at least in New England, was “basking shark,” and no one seemed to understand that the animal we call a basking shark today was definitely not the same thing!

    I am glad to see you didn’t put the megatooth in with the same genus as the great white. I’ve not seen any reason why it’s almost always listed in Carcharodon. It’s where it traditionally is placed, but all we have are teeth– which isn’t surprising considering that sharks don’t have bones–so how can we assume it was just a big great white?

    Link to this
  9. 9. naishd 8:52 am 08/6/2013

    Many thanks for excellent comments, much appreciated. In case it isn’t clear enough, this article is not meant in any way to endorse the idea that Megalodon might be extant, nor should it be seem as providing support for the crappy Discovery faux-documentary… just the opposite! (I thought this was abundantly clear from the article).

    Darren

    Link to this
  10. 10. naishd 9:04 am 08/6/2013

    The information on deep-diving behaviour in extant shark species, and on the possible non-presence of C. megalodon in the Pleistocene, is very much appreciated; thanks indeed.

    As for the inclusion of the species within Carcharodon, the primary case for this hypothesis was made by Gottfried et al. (1996). They argued (1) that C. carcharias appears to become more C. megalodon-like with increasing size, suggesting that C. megalodon is merely an ‘extrapolated’ version of Carcharodon; (2) that juvenile C. megalodon are, conversely, very C. carcharias-like; (3) that the “coronoin fibrous architecture” of the two species is highly similar; (4) that C. carcharias and C. megalodon are united by the presence of a uniquely symmetric second upper anterior tooth; (5) that both taxa also share relatively large, ‘reversed’ intermediate teeth; and (6) that both possess rounded tooth lobes, unlike the angular ones present in other lamnids.

    On the basis of these similarities, they argued that Megalodon should be put back into Carcharodon. Of course, other workers disagree, and it has been argued that Megalodon seems only convergently similar to Carcharodon

    Darren

    Link to this
  11. 11. Richard Freeman 10:20 am 08/6/2013

    I wonder how much this trip cost to make? It would have been better spent on an expedition in search of one of the more plausible cryptids.

    Link to this
  12. 12. Mike from Ottawa 10:38 am 08/6/2013

    Yes, but the more plausible cryptids don’t fit as well into Shark Week and I think we can fairly conclude that advancing science was not a priority on that project.

    Link to this
  13. 13. Chelydra 12:41 pm 08/6/2013

    How about whale falls as a food source for a mega-scavenger?Presumably these would have been fairly abundant until commercial whaling began.

    Link to this
  14. 14. Heteromeles 1:04 pm 08/6/2013

    @13: Actually, whale-falls are food for mega-sharks. Sixgills (Hexanchus griseus)aren’t exactly small sharks.

    As for the rest, I think the best response to the Megalodon focumentary is a long (and pained) silence. As some say, all publicity is good publicity, and this counts as publicity.

    Link to this
  15. 15. Ogre magi 1:47 pm 08/6/2013

    Can you give us a hint as to which beasts will be covered in this book? I would love to see how you could make the Yowie realistic (perhaps something along the lines of the marsupial ape from the spec dino project or the marsupial monkey from After Man)

    Link to this
  16. 16. Heteromeles 3:16 pm 08/6/2013

    Or how about the yowie as a boat-building giant hobbit from Flores? Amazing that there aren’t any humanoid cryptids from New Guinea, come to think of it. What’s up with that?

    Link to this
  17. 17. Jerzy v. 3.0. 3:38 pm 08/6/2013

    Is it possible that Megalodon was smallish or normal-sized shark with oversized teeth?

    Link to this
  18. 18. David Marjanović 3:54 pm 08/6/2013

    Still, I AM disappointed this particular piece of foetid effluvia turned up here. Don’t tell me SciAm has joined in Discovery Channel’s descent into fictional irrelevance, and is forcing their bloggers to publicize this stuff.

    …er… what…

    Is Discovery Magazine affiliated with Discovery Channel? Because here’s a post in a Discovery Magazine blog that doesn’t like the focumentary (I love that word!) very much at all.

    Link to this
  19. 19. Yodelling Cyclist 4:40 pm 08/6/2013

    Megalodon’s extinction surprises me a bit (though not to the point where I question the fact). Pleistocene cooling seems to get blamed a lot, but modern Great Whites and Makos can cope with really quite cool waters off South Africa, New Zealand and into the North Atlantic. Possibly this is another reason to be wary about extrapolating too far from modern sharks to Megalodon: modern sharks live on an ice-age world (for now), Megalodon’s soft tissue adaptations may have been really quite different.

    Link to this
  20. 20. altondooley 4:49 pm 08/6/2013

    @17: C. megalodon isn’t only known from teeth, although they are by far the most common remains. There are also a number of preserved vertebral centra from various localities, in some cases associated with teeth. These include both C. megalodon and ancestral forms (C. angustidens). The vertebrae confirm that it was, indeed, a very large shark and not an average shark with oversized teeth.

    See, for example:

    Gottfried, M.D. and Fordyce, R.E. 2001. An associated specimen of Carcharodon angustidens (Chondrichthyes, Lamnidae) from the Late Oligocene of New Zealand, with comments on lamnid interrelationships. Journal of vertebrate paleontology 21 (4): 730-739.

    There’s an image of a vertebrae from this specimen at:

    http://www.otago.ac.nz/geology/research/paleontology/c-angustidens.htm

    Link to this
  21. 21. Cameron McCormick 4:50 pm 08/6/2013

    Dartian #5:
    Giant squid sounds like an obvious food source

    Perhaps in this cryptid-filled alternate universe, Heuvelmans’ speculative hyper-giant squid with a 30+ meter entire length and Raynal’s giant cirroctopod “Otoctopus giganteus” with a 60 m armspan are also roaming around. Sperm Whales probably couldn’t swallow fully-grown (and presumably multi-tonne) members of these species… but perhaps Megatooth Sharks could rip them into bite-sized chunks. Additionally, in a “bigfoot bury their dead” situation, I’d imagine Megatooth Sharks eat the corpses of the numerous “sea serpent” species. /rampant speculation

    Link to this
  22. 22. LeeB 1 5:46 pm 08/6/2013

    Carcharocles megalodon isn’t the only big shark to disappear in the Pliocene, Parotodus benedini disappears about the same time. Also Isurus/Cosmopolitodus/Carcharodon hastalis evolved into Carcharodon carcharias so there was a turnover in the Lamnid shark top predators at that time.

    Relating the timing of this to the rapid increase in size of the Balaenoptera lineage might be interesting.

    LeeB.

    Link to this
  23. 23. Heteromeles 6:05 pm 08/6/2013

    @David: thanks for the link. Not that I’m supposed to be proud, but focumentary really just expresses how I feel about how low Shark Week sank this summer. Cut the fins off and threw it back, still alive, they did. Maybe they’ll go chumming for bull sharks with Honey Boo Boo next August.

    That said, I’m actually learning something about Megalodon and other sharks here, which is a pleasant and unexpected surprise.

    It would be interesting indeed if Megalodon was in a red queen race with baleen whales, and lost.

    Link to this
  24. 24. Yodelling Cyclist 6:12 pm 08/6/2013

    My understanding was that Carcharodon carcharias dates back to the late Miocene, so I wouldn’t say that its evolution should be tied to events surrounding the loss of Megalodon.

    Link to this
  25. 25. LeeB 1 7:01 pm 08/6/2013

    The intermediate evolutionary form Carcharodon hubbelli is 6.5my so C. carcharias must be slightly less than this presumably.
    So perhaps a bit too early to be the direct cause of the final extinction of C. megalodon but perhaps still involved in the size increase of Balaenoptera and part of the competition with smaller C. megalodon and P. otodus.

    LeeB.

    Link to this
  26. 26. Basandere 7:23 pm 08/6/2013

    I don’t have the words to say how much I love the “NOOOO” picture. :)

    Link to this
  27. 27. Boesse 8:41 pm 08/6/2013

    LeeB – remember that the Carcharodon hastalis-hubbelli-carcharias transition is a Pacific Basin phenomenon, and that during the early Pliocene there are still C. hastalis teeth in the Sunken meadow member of the Yorktown Formation (formerly units 1-2), and in the overlying Rushmere and Moore House Members there are fully serrated C. carcharias teeth. In the pacific, modern C. carcharias teeth are already present in most Pliocene units (uppermost Pisco Fm./Peru, Bahia Inglesa Fm./Chile, Purisima, San Mateo, San Diego, Niguel Fms./California) – and thus it could be argued that the final timing of global distribution/dispersal of C. carcharias into all major ocean basins (and not just the Pacific) agrees pretty well in terms of time with the extinction of C. megalodon. I’m not necessarily convinced that there’s any reasonable link with marine mammal biotic/evolutionary events/trends.

    Link to this
  28. 28. altondooley 9:55 pm 08/6/2013

    @23: I’ve also wondered if there was a “Red Queen” relationship between C. megalodon and mysticetes, at least in terms of the origin of large body size in the sharks. However, I doubt it had an effect on their extinction. On the US Atlantic Coast, there were already c.14+ meter balaenopteroids in the late Miocene Eastover Formation at around 7 million years (http://wp.me/p1CZX8-1w1), at least 2.5-3 million years before C. megalodon went extinct.

    Link to this
  29. 29. LeeB 1 12:32 am 08/7/2013

    Boesse- so did C. megalodon disappear earlier in the Pacific basin than in the Atlantic or Indean oceans?
    And likewise how does this compare with the disappearance times of P.benedini?

    altondooley- balaenopterids only got really gigantic in the few million years; perhaps the disappearance of gigantic sharks made this possible.

    Also there has been a change from gigantic predatory sperm whales in the Miocene to large (but not gigantic) pack hunting predatory dolphins as the top predators of other cetaceans today.

    LeeB.

    Link to this
  30. 30. Dartian 1:32 am 08/7/2013

    LeeB1:
    balaenopterids only got really gigantic in the few million years; perhaps the disappearance of gigantic sharks made this possible

    I think it’s more likely to have been the other way around. I.e., (some) baleen whales evolved gigantic body size in order to avoid shark predation. Under this scenario, the giant size of modern whales would then be an example of the ‘ghosts of predators past’ phenomenon.

    there has been a change from gigantic predatory sperm whales in the Miocene to large (but not gigantic) pack hunting predatory dolphins as the top predators of other cetaceans today

    True, but that need not have had anything to do with the sharks (giant or otherwise). It might have just been a consequence of competition for the same ecological niche between these two odontocete groups. Sort of like how creodonts were (presumably) outcompeted by carnivorans on land.

    Link to this
  31. 31. David Marjanović 6:14 am 08/7/2013

    creodonts were (presumably) outcompeted by carnivorans on land

    Is there actually any evidence for this?

    (Apart from the fact that there is no Creodonta. The oxyaenids may be carnivoromorphs, but the hyaenodontids are probably quite distantly related animals and came from Africa.)

    Link to this
  32. 32. altondooley 7:32 am 08/7/2013

    Dartian and LeeB1:

    It might be noteworthy that killer whales and false killer whales (the only odontocetes that seem to attack large whales) seem to show up at roughly the same time that giant sharks and killer sperm whales (although I should say that sperm whale fossils are so rare that their temporal ranges are not well known). Maybe pack-hunting odontocetes out-competed giant sharks, but I think it’s more likely they moved into the niche vacated by the sharks.

    Another interesting thing to consider: the disappearance of the giant sharks actually corresponds closely with the near-complete extinction of SMALL baleen whales. With the exception of Caparea, every extant baleen whale species is larger than any middle Miocene species, and small baleen whales were still common up into the Pliocene, but they were almost completely gone by the beginning of the Pleistocene.

    Link to this
  33. 33. Dartian 8:12 am 08/7/2013

    David:
    Is there actually any evidence for this?

    Admittedly, no. It’s presumption based on the fact that ‘creodonts’ and carnivorans did coexist for some time in some places but the former eventually went extinct. It’s possible and perhaps even likely that other factors (e.g., climate change, failure to keep up with the prey species’ adaptations) contributed more to the demise of the ‘creodonts’ – but surely competition* with other, contemporaneous flesh-eating mammals may have had at least some effect in the long run too?

    * Competition is, of course, a somewhat problematic concept in a biological context, and I use it here with reservation. It’s occurrence in nature is certainly often very hard to demonstrate. Historically, ‘competition’ has sometimes been used as a lazy catch-all explanation for some interactions between organisms in nature. On the other hand, it has also sometimes been defined so narrowly that almost nothing would really qualify as competition at the intertaxon level (there was some tendency among ecologists to do precisely that in the 1970ies and 1980ies). The tricky thing is to find some sensible middle ground between those extremes.

    The oxyaenids may be carnivoromorphs

    Whut?

    Hey, I just met you,
    and this is crazy,
    but here’s my number,
    so give me the reference, maybe?

    Link to this
  34. 34. Boesse 9:02 am 08/7/2013

    The apparent coincidence in timing between the appearance of Orcinus and extinction of C. megalodon has been noted before (in the Lindberg and Pyenson chapter in the 2006 Whales, Whaling, and Ocean Ecosystems volume). However, the Orcinus record is limited to a single tooth from Japan and Orcinus citoniensis, which is about half (or even less) the size, with smaller and more numerous teeth, and is hardly occupying the same niche as extant O. orca. I suspect that the large body size in the Orcinus lineage is a Quaternary phenomenon.

    Regarding mysticete body size… I would think that cooling sea surface temperature during the late Pliocene-Pleistocene interval is probably most responsible for the “across the board” increases in mysticete body size (or, at least selecting for extant large bodied taxa – Eubalaena, Balaena, Balaenoptera, Megaptera – while selecting against the small bodied taxa – Balaenula, smaller balaenopterids, and eventually poor little Herpetocetus).

    LeeB: I can’t talk about the Pacific extinction timing of C. megalodon quite yet. There’s a paper in the works.

    altondooley: “and small baleen whales were still common up into the Pliocene, but they were almost completely gone by the beginning of the Pleistocene.”

    Well, almost:
    Boessenecker, R.W. 2013. Pleistocene survival of an archaic dwarf baleen whale (Mysticeti: Cetotheriidae). Naturwissenschaften 100:4:365-371

    =D

    Link to this
  35. 35. altondooley 9:36 am 08/7/2013

    I knew you would mention that paper, Boesse! Even with that specimen, though, the little guys seem to have been on the decline for awhile before the Pleistocene.

    I agree that the mysticete size shift was probably climate controlled, but I’m not sure it was as simple as cooler temperatures = larger body size. I wonder if other oceanographic changes associated with a cooling climate may have a bigger effect.

    Link to this
  36. 36. Heteromeles 10:37 am 08/7/2013

    So do we have a link back to Caperea’s bizarre skeleton? Is it the equivalent of a Neptunic for a formerly Megalodon-filled Pacific?

    Link to this
  37. 37. Yodelling Cyclist 1:55 pm 08/7/2013

    I think discussing Megalodon extinction purely from the perspective of the smaller baleen whales may be a bit misleading – Megalodon has been linked to predation on a slew of other species, including dolphins, pinnipeds, and modern large whales. (I’m sorry but all the references are from Wikipedia). In addition, modern minke whales are not that much larger than known Megalodon targets, and do come into warm waters. Further – there are always calves.

    That said the loss of the smaller baleen whales is an interesting topic which I’m glad well informed individuals are discussing here.

    Link to this
  38. 38. Yodelling Cyclist 9:01 pm 08/7/2013

    Will the book contain ivory bills?

    Link to this
  39. 39. David Marjanović 5:24 am 08/8/2013

    Hey, I just met you,
    and this is crazy,
    but here’s my number,
    so give me the reference, maybe?

    :-D Shawn Zack’s PhD thesis, 2009, still unpublished. :-( I can send you the pdf if you find me in Google Scholar and drop me an e-mail.

    The paper that roots Hyaenodontidae in Africa is by Floréal Solé and came out in J. Syst. Palaeont. recently.

    Link to this
  40. 40. BrianL 10:45 am 08/8/2013

    @David Marjanovic:
    Can you tell us something more about the contents of that paper by Solé? Personally, I’m especially interested if it makes a case for afrotherian hyaenodonts (a pet hypothesis of mine).

    Link to this
  41. 41. David Marjanović 1:11 pm 08/8/2013

    Well, it doesn’t even try. Arguably it can’t, given the lack of a morphological placental phylogeny other than Zack’s thesis, which is a bit too small and a bit outdated among other things, and the recent Science paper (published too late for Solé to take it into account) which has an enormous character sample but a saddening taxon sample.

    Link to this
  42. 42. CraigYork 1:45 pm 08/8/2013

    I’ll be looking forward to the book, even though I suspect I won’t like a lot of the conclusions…( but
    thats beside the point. )

    I did watch the ‘special on Discovery, and it was fairly obvious, even to an armchair reader like myself, that this was another ‘Mermaids’ with a bit lower effects budget. But given what I’ve been seeing on a
    number of the ostensibly “Science” based channels, this
    is a trend that’s going to continue for some time. Even
    PBS has become a bit more commercially oriented in recent years. I hope Cryptozoologicon starts
    a reversal of that trend.

    Link to this
  43. 43. Mike from Ottawa 9:16 pm 08/8/2013

    The Daily Show, Comedy Central’s flagship news show did a piece on Discovery’s megalodon mess and were not exactly complimentary. Nice to see it’s more than just the science blogosphere and magazines.

    Link to this
  44. 44. Heteromeles 12:34 am 08/9/2013

    The episode can be seen at http://www.thedailyshow.com/full-episodes/wed-august-7-2013-lake-bell

    Hopefully, given the high ratings they got off that Megalodon focumentary, in 2014 Shark Week will kick off with Chumming with Honey Boo Boo… My other grumble about shark week is that the two or three semi-serious science program (for middle school levels of science) are broadcast before 9 a.m. or after 10 p.m. The rest of the time is wall-papered with reruns of great white garbage and, yes, megalodon. It doesn’t take much effort to not watch shark week, really.

    My grumpy theory is that Discovery’s marketing morons are telling them that smart people don’t watch TV any more, and so their core audience is on the down side of the digital divide and increasingly in red states. Slightly smarter marketroids would tell them that they’re driving intelligent viewers away with their idiotic programming choices (amish mafia and naked survival come to mind), but they don’t want to hear that. Heck, they’d do better broadcasting a live video feed from a den of skunks in someone’s basement.

    It’s kind of sad when baseball is actually among the smartest programming on basic cable during prime time.

    Link to this
  45. 45. Jenny Islander 1:40 am 08/9/2013

    I dimly remember poring over TV Guide and having to agonize over which Discovery programs I was actually going to watch, because I was still in high school, so I had to spend most of my time studying for my calc exam instead of grooving on juicy delicious crunchy meaty SCIENCE.

    O

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  46. 46. Jenny Islander 1:46 am 08/9/2013

    Ack! Finger slipped.

    Anyway, those were the days when you could get reporter-on-the-scene con reports on the Sci Fi Channel. And Ellison’s awesome rantage. And no wrestlers.

    I dropped cable years ago and it’s amazing how little I miss it.

    BTW, I posted this on an older thread, so I’m hoping it gets seen by more people here: My local public library is winnowing in preparation for a move to better quarters. Their most up-to-date bird book is Feduccia 1996. I was thinking of recommending The Inner Bird, but has something better come out since 2007? They will really only have room for one general-audience book on this topic.

    Link to this
  47. 47. naishd 4:18 am 08/9/2013

    Thanks to all for great comments – you’ve probably seen numerous other rants and critiques of the Discovery show elsewhere online by now… The Daily Show’s is one of the best.

    Jenny (comment # 46): sorry for not responding to the previous comment. There is indeed still a lack of a good book that reviews the bird fossil record – Kaiser’s The Inner Bird is not well illustrated enough to be as attractive to naive readers as Feduccia’s book is, and Chiappe’s Glorified Dinosaurs is restricted to Mesozoic birds (but it is very good). My bird chapter in The Complete Dinosaur, 2nd ed counts for something, but it’s buried in an enormous book that isn’t focused on birds. And I should also mention Katrina van Grouw’s The Unfeathered Bird (I haven’t read it, but the illustrations are incredible) and Dyke & Kaiser’s Living Dinosaurs.

    Darren

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  48. 48. BrianL 4:57 am 08/9/2013

    @Jenny Islander:
    Are you looking for a book on birds in general or on their evolution? If the latter, things are going to be a bit difficult, as Darren implied.
    I’d personally recommend ‘The Inner Bird’ but realise that, in focusing on showcasing anatomy, it chooses to follow Linnaeaus’ classification of birds as this was based on basic anatomical alikeness. As such, it isn’t on the ball regarding phylogeny. Also, it doesn’t delve into evolution much. As a result, this book is surely going to attract viewers (deservedly, it really is gorgeous) but won’t inform them well about the larger picture of bird evolution. Also note that the depictions of anatomy generally go without showing what the bird actually looks like alive and in the flesh.
    This book caters more to people with some pre-existing ornithological know-how than to the layman, I feel. If that isn’t a problem, I’d say go for it.

    Link to this
  49. 49. David Marjanović 2:16 pm 08/9/2013

    Dyke & Kaiser’s Living Dinosaurs

    is fucking amazing, it finally taught me what a cladogram really is.

    Alas, it was published in 1998. It’s seriously outdated. 1998 is the year *Caudipteryx* was described.

    it chooses to follow Linnae[...]us’ classification of birds

    That would be deeply surprising. I guess you mean Wetmore’s (1960) classification, which was taken for granted by books and museum collections till 1990?

    Link to this
  50. 50. BrianL 2:52 pm 08/9/2013

    @David Marjanovic:
    I do not mean Wetmore’s classification, I meant Linnaeus. The book really does that and yes, I found that deeply surprising too.

    Link to this
  51. 51. Jenny Islander 3:24 pm 08/9/2013

    Well, drat. There is a lot of good stuff in Feduccia’s book–as you say, it’s attractive to naive readers. All kinds of useful bits of trivia for enthusiasts like me sprinkle the pages. For instance, I had no idea that the large outer body and flight feathers all grow from distinct tracts, but there are scientific drawings showing exactly how it happens. There’s an awesome diagram showing exactly what all those shorebirds can do with their various beaks, which I never saw anywhere else. Lots of skeletal and life restorations, careful explanations of terminology, etc. (And then there are howlers like an aside that hadrosaurs were aquatic, in a book packed with cautionary examples of how failure to closely examine a fossil can lead a person astray, but nobody’s perfect.)

    I can sort of see his argument that (AFAICT) birds arose from thecodonts that were exploiting new arboreal habitats all over the planet with one population happening to hit on a gliding method that could lead to powered flight, while dinosaurs were at the same time developing from thecodonts that exploited habitats on the ground. Not saying I agree with it, but I think I follow his reasoning. His chapter on the descent of the flamingo is really fascinating–the way he pulls together life studies of modern birds, examination of fossils, analysis of fossil assemblages, etc., is compelling to this amateur. But there’s a remark in his section on Hesperornithiformes that seems impossible. He suggests that Hesperornis, for one, could have been viviparous based on its apparent lifestyle. I know that some reptiles were and are viviparous, but could a bird do it?

    Back on topic, I think I’ll recommend Chiappe. If they have room for two, maybe also The Inner Bird.

    Link to this
  52. 52. Jenny Islander 3:51 pm 08/9/2013

    Oh, and Feduccia’s book contains the only explanation I’ve ever seen of why certain bird groups tend to flightlessness more than others. Tying back into the main topic, this kind of thing provides a fun real-world underpinning for cryptozoological speculation, although I can’t offhand remember any monster that seems like a misidentified flightless bird. Wait, possibly the chickcharney.

    Link to this
  53. 53. naishd 4:07 pm 08/9/2013

    David (comment # 49): I’m pretty sure you’re thinking of Dingus & Rowe’s The Mistaken Extinction: Dinosaur Evolution and the Origin of Birds, not Dyke & Kaiser’s Living Dinosaurs.

    Jenny (comment # 51): you’re absolutely right about the level of detail and number of good diagrams in Feduccia’s book; as I said, there’s nothing else quite like it. It’s unfortunate that his views are so biased, idiosyncratic and ‘non-standard’. The ‘flamingos are shorebirds’ thing, for example, is indeed well explained and might look well supported, but – if you look in detail at his logic, it doesn’t fit the evidence better than do other hypotheses about flamingo evolution. He relies really heavily on the similarity that flamingos have with Cladorhynchus, so much so that flamingos are essentially made to look like the Cladorhynchus sister-group (in which case, flamigos are deeply nested within Recurvirostridae and Charadriiformes). Yet he explains in the same section (right hand of p. 199) that the similarities are convergent (which is what other researches have argued on the basis of more extensive character analysis), in which case… are those similarities with Cladorhynchus really as significant as he makes out? Contradictions like this are found throughout his book. Of course, since his book was published, improved evidence linking flamingos to grebes has been published and I don’t think anybody (other than Feduccia, probably) supports a nesting of flamingos within Charadriiformes. It certainly isn’t supported in any of the recent extensive molecular analyses of birds.

    I’ve said it before and I’ll say it again: people complain about Feduccia because of the erroneous things he says about bird origins, feathered non-avialan dinosaurs and whatnot, but they don’t make a big enough deal of the fact that his arguments about neornithine evolution are equally as idiosyncratic, non-standard and problematic.

    Darren

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  54. 54. Lars Dietz 8:19 am 08/10/2013

    BrianL: Do you mean The Unfeathered Bird? I don’t have it, but I read in a review that it uses Linnaeus’ classification, as a way to show ecologically similar birds next to each other. The Inner Bird isn’t organized according to any particular classification, but it does talk about the history of bird classification.

    Link to this
  55. 55. BrianL 8:23 am 08/10/2013

    @Lars Dietz:
    Woops, I did make that mistake. A howler! I definately had ‘The Unfeathered Bird’ in mind when I wrote that.

    Link to this
  56. 56. David Marjanović 11:20 am 08/12/2013

    And then there are howlers like an aside that hadrosaurs were aquatic

    Worse. The context for this was the argument that predator/prey ratios suggest endothermy in Late Cretaceous dinosaurs. Feduccia replied, not quite in those words but close, “LOL, everybody knows the most abundant herbivores were aquatic and theropods were somehow unable to swim; those people are so stupid they haven’t noticed for 20 years that the predator/prey ratios are just taphonomy!” He clearly had no idea how deeply embarrassing it was to say such a thing in 1996. *headdesk* *headdesk* *headdesk*

    I can sort of see his argument that (AFAICT) birds arose from thecodonts that were exploiting new arboreal habitats all over the planet with one population happening to hit on a gliding method that could lead to powered flight, while dinosaurs were at the same time developing from thecodonts that exploited habitats on the ground. Not saying I agree with it, but I think I follow his reasoning.

    Unfortunately, his reasoning consisted mostly of holes. First of all, Feduccia didn’t even try to figure out “thecodont” (archosaur) phylogeny, he treated the “thecodonts” as a black box instead; he didn’t even try to figure out which animals are “thecodonts” and which are not! Megalancosaurus is not an archosaur or even more generally an archosauriform, and Longisquama probably isn’t even a crown-group diapsid (M. may not be either)! And how exactly do you get from gliding to powered flight? Feduccia didn’t even mention that there’s a discussion to be had there.

    His chapter on the descent of the flamingo is really fascinating–the way he pulls together life studies of modern birds, examination of fossils, analysis of fossil assemblages, etc., is compelling to this amateur.

    Alas, it’s nothing but compelling. It’s nothing but a beautiful, detailed just-so story. Feduccia didn’t try to test it. Phylogenies can test evolutionary scenarios, not the other way around as Feduccia evidently believed.

    I know that some reptiles were and are viviparous, but could a bird do it?

    AFAIK, archosaur embryos take their calcium from the shell, not from the yolk, and therefore the eggshell cannot be lost in birds, crocodiles, and everything in between.

    I’m pretty sure you’re thinking of Dingus & Rowe’s The Mistaken Extinction: Dinosaur Evolution and the Origin of Birds, not Dyke & Kaiser’s Living Dinosaurs.

    *headdesk* Speaking of deep embarrassment, I’m indeed talking about the former. I managed to confuse Dingus and Dyke, and I had forgotten what the subtitle of The Mistaken Extinction was… I think I haven’t even read Living Dinosaurs.

    I read in a review that it uses Linnaeus’ classification, as a way to show ecologically similar birds next to each other

    …Wow. That means doing to a lot of work for little benefit.

    Link to this
  57. 57. Yodelling Cyclist 7:12 pm 08/12/2013

    AFAIK, archosaur embryos take their calcium from the shell, not from the yolk, and therefore the eggshell cannot be lost in birds, crocodiles, and everything in between.

    Are we including Metriorhynchids here? Because there’s a group with some serious marine adaptations.

    Oh, and fewer *headdesks* – it’s for your own good. You may have more neurons than the rest of us, but percussive maintenance of the noggin is always deleterious.

    Link to this
  58. 58. naishd 7:32 pm 08/12/2013

    There are several proposed constraints that might prevent crown-archosaurs (at least) from evolving viviparity, including the Calcium Budget Hypothesis alluded to above, the form of the archosaurian oviduct and the way in which embryos receive oxygen, and the presence of an air-sac system (inferred to require shelled eggs). However, viviparity has been suggested for both hesperornithines and metriorhynchoids. For the former, it’s just a hunch. For the latter, it’s based on the peculiar form of the pelvis and sacrum (Mark Young and colleagues referred to this in one of their recent papers, I’d had to check to see which one).

    Darren

    Link to this
  59. 59. Yodelling Cyclist 6:05 am 08/13/2013

    I seem to recall that this has been discussed here before – David Marjanović made a passing allusion to a suggested hesperornithine colony/nest site ashore, but I don’t think he provided a reference – any chance of getting that resolved?

    Link to this
  60. 60. David Marjanović 9:52 am 08/13/2013

    For the latter, it’s based on the peculiar form of the pelvis and sacrum (Mark Young and colleagues referred to this in one of their recent papers, I’d had to check to see which one).

    Interesting.

    David Marjanović made a passing allusion to a suggested hesperornithine colony/nest site ashore, but I don’t think he provided a reference

    I didn’t, because I don’t have one. Secondary literature has occasionally mentioned it for years; IIRC, it’s supposed to be in the Canadian Arctic and in some way related to the local hesperornithid Canadaga, which in turn isn’t well known.

    Link to this
  61. 61. Yodelling Cyclist 10:33 am 08/13/2013

    Even if a bone bed corresponding to a colony were found, that does not preclude live birth (by whatever method). Egg shells would be the minimum requirement, I guess.

    Link to this
  62. 62. Boesse 11:58 pm 08/13/2013

    Too bad this discussion devolved from a truly fascinating subject (marine vertebrates) to dinobirds
    D=

    Link to this
  63. 63. naishd 4:01 am 08/14/2013

    Huh, stupid dinobirds!

    Darren

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  64. 64. David Marjanović 6:11 am 08/14/2013

    Hesperornithes.

    Your argument is invalid.

    Link to this
  65. 65. llewelly 8:23 am 08/14/2013

    “Even if a bone bed corresponding to a colony were found, that does not preclude live birth (by whatever method). Egg shells would be the minimum requirement, I guess.”

    I don’t see why. There is only one instance (so far) of archosaurs evolving viviparity. So egg-laying on land should be the default, unless there are very good reasons otherwise.

    Even if Hesperornithes turn out to be viviparous, viviparity would still be very rare among archosaurs, and thus not the default.

    Link to this
  66. 66. Jenny Islander 3:59 pm 08/14/2013

    So would the really seallike birds that apparently couldn’t even stand up be lying on their tummies, carefully breast-brooding the eggs?

    Back on topic: I think it would be cool to see a series of nature pages in the style of the inner back cover of Ranger Rick, but featuring cryptids and/or extinct species as if they were as well known as black bears or robins. “If you live in sasquatch country, here’s what to do if a sasquatch shows up at your picnic.” “The giant unicorn is the most magnificent beast you will ever see in a zoo. Its fur is 4 inches long!” That kind of thing.

    In Megalodon Alley, do fishing boats carry dolphin guns, which fire painful dolphin-butting-style non-lethal rounds because actually killing the shark would just prompt a massive frenzy? Is Megalodon Alley a refuge for big whale species because Megs have learned to follow whaling vessels and snatch the catch?

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  67. 67. armadillozenith 6:04 pm 08/14/2013

    “Sharks aren’t tetrapods (and hence aren’t ordinarily part of the Tet Zoo remit)”

    SO weird. Today’s Metro (chatty newspaper free at UK train and bus stations) referred to ‘sharks’ (I kid you not) as ‘mammals’! So there you go, Darren: Metro just legitimised their inclusion here.
    This clanger was in an article, quite interesting, with photo showing a ‘shark-whisperer’ diver with a shark posed vertically tail-up upon his hand, reportedly in a state of ‘tonic paralysis’ after having its snout rhythmically stroked. (I have felt a similar effect myself from Indian Head Massage, or even from a haircut back when I had more hair.)

    The synchronicity seems suspiciously coincidental though. May there be a Metro insider, Darren, who’d read your piece a few days previously and thought they’d do you a favour by nudging sharks into the tetrapod via an opportune article?

    Link to this
  68. 68. David Marjanović 8:11 pm 08/14/2013

    There is only one instance (so far) of archosaurs evolving viviparity.

    …No idea what you’re thinking of. Even champsosaurs aren’t archosaurs.

    So would the really seallike birds that apparently couldn’t even stand up be lying on their tummies, carefully breast-brooding the eggs?

    Probably… or perhaps they let the sun do it, or something… how about burying the eggs in sand turtle-style?

    Link to this
  69. 69. Chabier G. 6:14 am 08/15/2013

    Well, Loons (Gaviiformes) can’t stand up (or can do it only for few seconds, but they brood eggs.

    Link to this
  70. 70. AlHazen 10:10 pm 08/15/2013

    “Thecodont” was used for a grade group of primitive archosaurs (archosauroforms, archosauromorphs, whatever). The precedent of “Birds are dinosaurs” seems to be that a traditional name for an extinct grade group gets reinterpreted as referring to the clade containing it and its descendants. So… wouldn’t it be consistent to interpret “Thecodont” as referring to.. well, roughly the total group of archosaurs? At which point “Birds are descended from (and, indeed, are) thecodonts” would come out true!

    Link to this
  71. 71. Michał 3:58 pm 08/16/2013

    Well, M. Mortimer did note on Dinosaur Mailing List that there is a somewhat obscure publication that redefined Thecodontia as the least inclusive clade containing Thecodontosaurus and Protorosaurus (presumably because these were included in Thecodontia by Owen back when the group was first named… though if that indeed was the intention, then Bathygnathus the synapsid should have been made another specifier, making Thecodontia synonymous with Amniota). This definition apparently isn’t in wide use though.

    Link to this
  72. 72. Teddy01 8:59 pm 08/21/2013

    @altondooley and Boesse,

    Wasn’t Otodus megalodon (I use Otodus following the update of Cappetta 2012) already understood to have preyed or at least fed on large baleen whales ?

    I remember the excellent Nat Geo doc about meg which talked that it employed different technics depending the size of the whale, a crushing, direct attack on smaller whales (cetotherids) like suggested by Brett Kent and an attack on the propulsive structures (tail region) on the larger whales. They also discussed that one on these balaenopterid prey item (explained by Lawrence Barnes) was very large at a possible 21-24 m long, weighing slightly more than O. megalodon.

    There is also this quote by Leonard Compagno (1990) : “various reconstructions of C. megalodon jaws suggest this shark had a predatory apparatus able to inflict mortal wounds even to a fin whale or a blue whale”.

    Based on these suggestions, I doubt that megalodon was necessarily limited to the smaller genera only ?

    Link to this
  73. 73. Teddy01 9:03 pm 08/21/2013

    Note : the Nat Geo doc specified that these larger balaenopterids justly occurred during the Pliocene.

    Link to this
  74. 74. Mudbud79 3:24 am 01/10/2014

    You know now that I’m looking at it from different points of View I’m thinking
    That megalodon might be a radioactive shark from the radioactive leak in japan
    Think about

    Link to this

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