Top 4 most annoyingly-popular dino hypotheses.

[HD-man]

I originally posted the following at deviantART ( http://jd-man.deviantart.com/journal/SD-Top-4-most-annoyingly-popular-dino-hypotheses-395469447 ). Now, I'd like to know what you guys think are the most annoyingly-popular dino hypotheses in recent years & why.

Hi everybody,

This journal entry was inspired by the Nostalgia Critic's "Top 10 Films I Hate But Everyone Else Loves" ( https://www.youtube.com/watch?v=-ejMFvssoSI ). It's nothing formal, just a list of what I (as a non-expert dino fan) think are the most annoyingly-popular (I.e. More popular than they should be given the evidence) dino hypotheses in recent years (I.e. Post-2000) & why. Even still, I hope that at least some of you will get something out of it. As for why "Top 4", to quote Santa Claus ( http://www.youtube.com/watch?v=Y_KMYPsPNXQ ), "I've� checked it more than once, but� less than 10 times, because around 4 I get bored."

Cheers,
Herman Diaz

4) Troodon, Oviraptor, & Citipati in particular & non-bird maniraptorans in general had paternal care, "possibly within a polygamous mating system" ( http://www.esf.edu/EFB/faculty/documents/varricchio2008paternalcaredinosours.pdf ). I have 2 major problems w/this hypothesis: 1) Varricchio et al. use maximum rather than average values for clutch size (which doesn't make sense to me given that "Troodon clutches vary from 12 to 24 eggs": http://studentresearch.wcp.muohio.edu/vertebrateevolution/dinoasurreprodparenting00.pdf ); 2) Varricchio et al. focus "on the absence of medullary bone to weigh the data, for which a single troodontid specimen and a single specimen of *Citipati osmolskae* are exemplars of" (which doesn't make sense to me given that "multiple brooding oviraptorids are known": http://web.archive.org/web/20111120174744/http://dml.cmnh.org/2011Jan/msg00260.html ).

3) Dracorex & Stygimoloch were juvenile & sub-adult stages, respectively, of Pachycephalosaurus ( http://www.plosone.org/article/info:doi%2F10.1371%2Fjournal.pone.0007626 ). I have 2 major problems w/this hypothesis: 1) It's based on a CAST of the Dracorex skull, & thus it ignores the adult features of the original skull (See "DISCUSSION": https://web.archive.org/web/20100613092039/http://www.childrensmuseum.org/themuseum/dinosphere/draco_rex/dracorex_hogwartsia.pdf ); 2) It ignores the non-ontogenetic differences btwn Dracorex & Stygimoloch (Again, see "DISCUSSION").

2) Deinonychus in particular & non-bird theropods in general were like Komodo dragons in that they hunted alone or in non-cooperative mobs & not cooperative packs ( http://pds17.egloos.com/pds/201004/29/62/Theropod_Dinosaur.pdf ). I have 2 major problems w/this hypothesis: 1) Some of its arguments are very misleading (if not just plain wrong);* 2) It ignores MOR 682 (See the Maxwell quote) despite having cited Maxwell & Ostrom 1995 ( https://sci-hub.tw/https://www.jstor.org/stable/4523664?seq=1 ).

1) Sauropods lacked an avian-style gastric mill & compensated for this "by greatly increasing food retention time in the digestive system" ( http://rspb.royalsocietypublishing.org/content/274/1610/635.full.pdf ). I have 2 major problems w/this hypothesis: 1) It's based on the comparison of sauropod gastroliths to ostrich gastroliths while ignoring moa gastroliths; Like sauropods, moas were herbivorous browsers (See the Shugart quote) while ostriches are omnivorous grazers ( http://wildwelfare.org/wp-content/uploads/2017/09/Common-Ostrich.pdf ); It's probably no coincidence, then, that like sauropod gastroliths, moa gastroliths are polished (Again, see the Shugart quote) while ostrich gastroliths are pitted; 2) It fails to explain sauropod digestion for the same reason that gigantothermy fails to explain non-bird dino physiology; To quote Holtz, it "might apply to large dinosaurs, but would not apply to small species or to babies" (See "Gigantothermy" under "Complications": http://www.geol.umd.edu/~tholtz/G104/lectures/104endo.html ).

Dishonorable Mention) The Lark Quarry Dinosaur Tracksite records neither a large theropod ( http://www.uq.edu.au/dinosaurs/documents/Romilio_Salisbury_2010.pdf ) nor a dinosaur stampede ( http://www.uq.edu.au/dinosaurs/documents/Romilio_et_al_2013.pdf ). Poropat's & Thulborn's DML posts ( http://comments.gmane.org/gmane.science.dinosaurs.general/56325 ) sum up my problems w/this hypothesis. However, this hypothesis didn't make the "Top 4" for 2 main reasons: 1) It's more recent than all of the aforementioned hypotheses; 2) It's already been dissected in the literature ( http://www.tandfonline.com/doi/abs/10.1080/03115518.2013.748482?journalCode=talc20 ).

*E.g. It's implied that lone adult Komodo dragons can kill prey 10x their size w/"only ser- rated teeth", the logic being that lone adult Deinonychus would've done the same. However, it's been known since 2005 that the former are venomous ( http://www.academia.edu/462746/Early_evolution_of_the_venom_system_in_lizards_and_snakes ), hence why they can kill prey 10x their size. It's also implied, based on Horner & Dobb 1997, that the multiple Deinonychus individuals represented at YPM 64-75 were immature, the logic being that "larger (older) animals are more voracious cannibals than smaller (younger) animals, and smaller conspecifics are more often eaten than larger". However, Horner & Dobb 1997 is neither a peer-reviewed source nor points to a peer-reviewed source, & thus "the information is not likely to be useful" ( http://anthropology.ua.edu/bindon/ant570/pap_rule.htm ). AFAIK, the only relevant peer-reviewed source is Ostrom 1969 (according to which there is no "evidence of immature individuals at this site": http://peabody.yale.edu/sites/default/files/documents/scientific-publications/ypmB30_1969.pdf ).

Quoting Maxwell ( http://www.naturalhistorymag.com/htmlsite/master.html?http://www.naturalhistorymag.com/htmlsite/1299/1299_feature.html ): "Laid out in its death pose at this new site was a beautifully preserved, near-complete specimen of a young Tenontosaurus. Four Deinonychus teeth were found alongside the bones; later, in the laboratory, seven more teeth were uncovered. It's possible that a few more teeth were missed in the field or unwittingly discarded during preparation because they were concealed within small lumps of rock. So we have a subadult Tenontosaurus no more than fourteen feet long (compared with a length of about twenty feet for the adult at the Shrine site), preserved with at least eleven Deinonychus teeth.

But how can we distinguish between the remains of a victim hunted down and devoured by a pack and an animal that simply died and was scavenged by a few passing Deinonychus? As is the case at the Shrine site, this Tenontosaurus was preserved where it died. After death, the desiccation of the abundant supporting tendons that line the vertebrae of the neck and tail cause these parts to coil. The tail of Tenontosaurus, which accounts for about one-third of the animal's total length, is particularly heavy with supporting tendons. In this specimen, the pronounced curvature of the tail and the neck toward each other effectively counters any claim that the bones were carried to the site by water currents. The Deinonychus teeth were found in the region of the abdomen and pelvis, suggesting that the predators lost their teeth while feeding on the viscera. Most modern carnivores begin with the areas around the anus and abdomen when they feast on freshly killed prey, and it's likely that carnivorous dinosaurs did the same.

The number of teeth indicate that more than one Deinonychus was involved with the carcass. Like all other theropod dinosaurs, Deinonychus shed and replaced teeth throughout its life. The teeth would fall out upon the animal's reaching maturity but also could be wrenched out earlier by the stress associated with the biting and tearing of flesh. Because of this, theropod teeth are very common in sediments containing dinosaur fossils. The teeth from this site vary from recently erupted to fully mature ones. Given that Deinonychus had only sixty teeth in its jaws at any one time, it's unlikely that all eleven were wrenched from the mouth of just one feeding animal. This would leave the Deinonychus toothless after five similar meals. The possibility that Deinonychus was replacing shed teeth in a few weeks or months, and therefore had the ability to sustain such dramatic tooth loss, was quashed by Greg Erickson, who, as a master's degree student at the Museum of the Rockies, worked on replacement rates of teeth in various dinosaurs and living reptiles. After CT-scanning portions of the lower jaw of Deinonychus and studying individual teeth, he came up with an estimate of 300 days for the time it took Deinonychus to replace a shed tooth with a mature one.

We know that this Tenontosaurus was not yet an adult, so it didn't die of old age. Of course, this doesn't rule out death from disease or injury and doesn't confirm that it was cut down by a pack, but it's a start. Next, we have a concentration of teeth around the abdomen and pelvis. This may indicate that the pack fed on the abdominal contents while they were still warm and moist. If, after the viscera had been consumed, the remainder of the carcass was scavenged over time by many individuals, we would expect a much more disturbed carcass and a wider scattering of teeth. Similarly, if the Tenontosaurus had been killed by a larger predator-such as the unknown owner of the three-inch-long serrated teeth that occasionally crop up in the Cloverly formation—then whatever remained of the carcass would have been strewn around the area."

Quoting Shugart ( http://www.amazon.com/Earthquake-Other-Tales-Unbalanced-Nature/dp/0300122705 ): "When the Polynesians arrived in New Zealand, they encountered birds that had been evolving for 80 million years without the presence of mammalian predators. Among the most striking of these animals must have been the moas (Figure 29). These were gigantic wingless birds standing as much as 10 feet (3 m) tall and weighing as much as 550 pounds (250 kg).1 They are known from a diverse array of remains including eggshells, eggs, a few mummified carcasses, vast numbers of bones, and some older fossilized bone. The eleven moa species that are currently recognized occupied ecological niches customarily filled elsewhere by large mammalian browsing herbivores. They may have had relatively low reproductive rates; apparently, they usually laid only one egg at a time.2
Moas ranked in height from the tallest at about 10 feet to smaller species the size of a large domestic turkey (about 3 feet, or 1 m, tall and weighing 45 pounds, or 20 kg). They were unique in having neither wings nor even residual wing bones. As one expects of large birds that feed on vegetable matter, moas had muscular gizzards. They swallowed small stones up to 2 inches (50 mm) in diameter into their gizzards for grinding food before digestion. These polished stones, called gastroliths, often occur in groups along with moa bones.3
Many gastroliths have been found in what are now human-modified grassy habitats, giving the initial impression that moas were grass-eating animals. But the present vegetation at a site may not be its previous vegetation.4 Based on preserved crop contents from mummified specimens, moas fed on leaves, seeds, and green twigs of trees and parts of shrubs.5 Thus, it appears that they were creatures of the forest and shrub- land—more like browsing deer than grazing cows."

[Dinoguy2]

So this is basically "hypotheses that were  popular 20 years ago that are now out of favor based on more recent evidence but I don't like my old-school dino books being wrong..."?

These seem to be unpopular refutations of popular hypotheses, not really ideas that are popular in their own right.

[HD-man]

So this is basically "hypotheses that were  popular 20 years ago that are now out of favor based on more recent evidence but I don't like my old-school dino books being wrong..."?

More like "relatively recent hypotheses that are seemingly being taken at face value despite a lack of supporting evidence &/or an abundance of contradictory evidence".

[fleshanthos]

Ya.  Panda bears aren't bears! They're MARSUPIALS!













____________________  * uh no. Just the opposite.

[HD-man]

Ya.  Panda bears aren't bears! They're MARSUPIALS!

Out of curiosity, are you were referring to what Moses Salmeron said ( http://www.sfgate.com/news/article/A-Bear-of-a-Research-Challenge-2767023.php )?

[fleshanthos]

No, I came across an amazing cover song by KT Tunstall (I Want you Back) and then had some stuff she did playing in the background while I did some work. It was a weird "fact" that some teenager gave her....*sigh*

What bugs me more are the grossly inaccurate models - especially the older ones like Aurora. But I wasn't bugged enough to avoid Papo models.

[Splonkadumpocus]

What really annoys me about the whole panda thing is that we know the giant panda is a type of bear now, yet people still insist on correcting anyone who uses the term "panda bear."

[Brontozaurus]

I find it really funny that you have exactly two problems with all those hypotheses.

Re: sauropod digestion, while gastrolith shape may not be an issue, there's still the fact that gastroliths aren't associated with the majority of sauropod skeletons (which should be expected if they were so important to digestion), nor are they found in quantities that would be suitable for digestion in such large animals.

[HD-man]

I find it really funny that you have exactly two problems with all those hypotheses.

I actually have more problems w/some of the aforementioned hypotheses than I do w/others. It's just that 1) I knew the journal entry was gonna run long, so I narrowed the problems down to the most major ones (hence why I said "I have 2 major problems w/this hypothesis"), & 2) I always try to be consistent.

Re: sauropod digestion, while gastrolith shape may not be an issue, there's still the fact that gastroliths aren't associated with the majority of sauropod skeletons (which should be expected if they were so important to digestion), nor are they found in quantities that would be suitable for digestion in such large animals.

Skulls "aren't associated with the majority of sauropod skeletons" either. Point is, sauropods skeletons are often incomplete. However, given that gastroliths have been found w/a variety of sauropod skeletons (Jurassic & Cretaceaous, diplodocoid & macronarian, etc) & at least sometimes in suitable quantities (See the highlighted paragraph: http://books.google.com/books?id=RDq5Szn7afoC&pg=PA219&dq=%22occasional+sauropod%22&hl=en&sa=X&ei=kFZCUuiuKozl4APayYCwBw&ved=0CC8Q6AEwAA#v=onepage&q=%22occasional%20sauropod%22&f=false ), I think it's still safe to say that gastroliths were important to sauropod digestion.

[Balaur]

Ya.  Panda bears aren't bears! They're MARSUPIALS!

Funny thing is that Koala bears aren't bears. They're marsupials! And that statment is actually true. Unlike the Panda ine. 

[fleshanthos]

Yea, Brontoz, before I read HD man it occurred to me that the gastroliths could easily be washed away by a current, or else dropped to a waterbed if the carcass floated with bloat for awhile and then blew open in compartments. Digestive system being the main source of gas, I would postulate. The system carrying the gastroliths.

[Brontozaurus]

But the fact is that there would need to be loads and loads and loads of gastroliths for a very large sauropod to efficiently use them for digestion, so even when we find them, there should be a lot more then we see.

[Ultimatedinoking]

Ya.  Panda bears aren't bears! They're MARSUPIALS!



No, the Panda (Ailuropoda melanoleuca) is in fact a bear. Although a very unusual one...









____________________  * uh no. Just the opposite.

[HD-man]

But the fact is that there would need to be loads and loads and loads of gastroliths for a very large sauropod to efficiently use them for digestion, so even when we find them, there should be a lot more then we see.

Again, that's primarily based on the comparison of sauropod gastroliths to ostrich gastroliths while ignoring moa gastroliths (See my 1st comment). Also again, gastroliths have at least sometimes been found in suitable quantities (See my previous comment).

[tyrantqueen]

The book Biology of the Sauropod Dinosaurs: Understanding the Life of Giants discussed in great detail the digestion and feeding habits of sauropodomorphs, even down to what their favourite food probably was. However, the authors rejected the idea of a gastric mill in sauropods, instead hypothesising that sauropods implemented some sort of gut fermentation instead

You might want to check the book out of you're curious about how such massive animals sustained themselves on a diet of plants and grew to such enormous sizes

[HD-man]

However, the authors rejected the idea of a gastric mill in sauropods, instead hypothesising that sauropods implemented some sort of gut fermentation instead

You might want to check the book out of you're curious about how such massive animals sustained themselves on a diet of plants and grew to such enormous sizes

Thanks, but I already have. Thing is, in Biology of the Sauropod Dinosaurs: Understanding the Life of Giants, the "gut fermentation" hypothesis is seemingly taken at face value despite the problems listed in my 1st post.

[wings]

Thanks, but I already have. Thing is, in Biology of the Sauropod Dinosaurs: Understanding the Life of Giants, the "gut fermentation" hypothesis is seemingly taken at face value despite the problems listed in my 1st post.

1) Sauropods lacked an avian-style gastric mill & compensated for this "by greatly increasing food retention time in the digestive system" ( http://rspb.royalsocietypublishing.org/content/274/1610/635.full.pdf ). I have 2 major problems w/this hypothesis: 1) It's based on the comparison of sauropod gastroliths to ostrich gastroliths while ignoring moa gastroliths; Like sauropods, moas were herbivorous browsers (See the Shugart quote) while ostriches are omnivorous grazers (See "Species Characteristics": http://informedfarmers.com/rhea-production/  ); It's probably no coincidence, then, that like sauropod gastroliths, moa gastroliths are polished (Again, see the Shugart quote) while ostrich gastroliths are pitted;...

We probably didn't have enough samples to make such statement (see Gillette 1996, http://www.columbia.edu/dlc/cup/gillette/gillette16.html); texture wise possibly they vary in degree of "polishness" (as in figure 1a-slightly pitted or 1b-well polished in Wings and Sander 2013). Here is part of Gillette's description (see below):

"...Sam's gastroliths are all rounded, and some are highly polished. Their surface texture ranges from dull to waxy, in accordance with the degree of polishing. Except for breakage during excavation, none of the gastroliths have sharp edges; even the ones with irregular shapes are highly rounded...Not all of Sam's gastroliths, however, display a waxy surface. To the unaided eye, they range from highly polished and waxy to dull and pitted..."

I'm not sure if we can generalize this right now, maybe this depends on the species and/or the plants they eat.

Percentage wise if we compare Wings and Sander's finding on the ostriches and we use the Moas instead; do we really see a great difference in the number? I'm not so sure since the number is quite miniscule. Wings and Sander's number is averaging about 1% (gastrolith to total body weight) in ostriches and less than 0.1% in sauropods. Now what about the Moas? In the table (table 5.11) provided in Worthy and Holdaway (2002), still none of the findings indicate a percentage less than 0.1% (it ranges from 0.17% in Euryapteryx curtus to 4.52% in Dinornis giganteus).

I'm not saying that they don't have gastric mills but all I'm saying is that the above concerns is almost a non-issue at this point in time.

[HD-man]

We probably didn't have enough samples to make such statement

Actually, even if we don't include Seismosaurus, we probably do (To quote Bakker, "I have seen a half- dozen brontosaur bodies in the field where smoothly rounded pebbles were scattered through and around the ribs": http://www.docstoc.com/docs/159410584/The-Dinosaur-Heresies-New-Theories-Unlocking-the-Mystery-of-the-Dinosaurs-and-Their-Extinction-by-Robert-T-Bakker ).

Percentage wise if we compare Wings and Sander's finding on the ostriches and we use the Moas instead; do we really see a great difference in the number? I'm not so sure since the number is quite miniscule. Wings and Sander's number is averaging about 1% (gastrolith to total body weight) in ostriches and less than 0.1% in sauropods. Now what about the Moas? In the table (table 5.11) provided in Worthy and Holdaway (2002), still none of the findings indicate a percentage less than 0.1% (it ranges from 0.17% in Euryapteryx curtus to 4.52% in Dinornis giganteus).

1stly, while gastrolith percentage may be a non-issue, it's worth mentioning that that of E.curtus is both significantly less than that of the Ostrich & significantly closer to that of Seismosaurus.

2ndly, even if gastrolith percentage is a non-issue, that still doesn't explain the problems listed in my 1st post. Sampson summarized the gastrolith debate best when he said, "It's been argued that the total mass of stomach stones found in association with sauropods specimens is insufficient to support the idea of a gizzard. Even more damaging is a recent study indicating that the bulk of these supposed stomach stones, rather than being polished within the guts of ancient dragons, are merely water-rounded cobbles washed down into the Morrison Formation from overlying Cretaceous sediments. Nevertheless, occasional sauropod skeletons do show appropriately sized cobbles within the rib cage, suggesting that rock-filled gizzards may have been part of the digestive solution for at least some of these dinosaurian giants" (See Chapter 13 of Dinosaur Odyssey: http://www.doc88.com/p-102817110518.html ). It's also worth reading Chapter 6 of The Dinosaur Heresies (which is where the Bakker quote is from) for more info about both moa & sauropod gastroliths.

[wings]

Actually, even if we don't include Seismosaurus, we probably do (To quote Bakker, "I have seen a half- dozen brontosaur bodies in the field where smoothly rounded pebbles were scattered through and around the ribs": http://www.docstoc.com/docs/159410584/The-Dinosaur-Heresies-New-Theories-Unlocking-the-Mystery-of-the-Dinosaurs-and-Their-Extinction-by-Robert-T-Bakker ).

To find an exception just demonstrate the possibility so I don't see why we have to generalize it (and just to clarify before you misunderstood again; I was just referring to the texture but not the function of them (gastroliths)). No doubt there are plenty of gastrolith that have a smooth texture but there are also examples suggest otherwise.

...even if gastrolith percentage is a non-issue, that still doesn't explain the problems listed in my 1st post... occasional sauropod skeletons do show appropriately sized cobbles within the rib cage, suggesting that rock-filled gizzards may have been part of the digestive solution for at least some of these dinosaurian giants" (See Chapter 13 of Dinosaur Odyssey: http://www.doc88.com/p-102817110518.html ). It's also worth reading Chapter 6 of The Dinosaur Heresies (which is where the Bakker quote is from) for more info about both moa & sauropod gastroliths.

That was never my argument. Here is what has been said in the original post "...I'm not saying that they don't have gastric mills ...". My statement never implied that the gizzard in sauropods can't be part of the digestive system.  Bakker's book is fine but Worthy and Holdaway (2002) gives more quantitative measurements which can be compare with.

Also E.curtus was included because it is part of the group (Moa); and let say we ignore Euryapteryx then the finding would become even more favorable to Wings and Sander's conclusion using just the ostriches...

I would assume your recent study would be Lucas(2000) and this is his conclusion (see below).

"...These studies need to be repeated with unquestioned gastroliths, and the gastroliths should be compared to fluvial clasts of identical petrology. Only then might a relationship between degree of polish and gastroliths be established."

I'm not sure whether a more in-depth study was conducted since; so all can be said is it's possible and we need more (gastroliths and fluvial sediments) for comparison.

[HD-man]

To find an exception just demonstrate the possibility so I don't see why we have to generalize it. No doubt there are plenty of gastrolith that have a smooth texture but there are also examples suggest otherwise.

I was just saying that we probably have enough samples to generalize sauropod gastroliths as polished ("generalize" being the key word).

That was never my argument.

I never said it was. I was just clarifying. As for Bakker's book, that was for more info about gastroliths that hypothesis #1 supporters ignore (Not saying that you're 1 of them; Just trying to be helpful).

I would assume your recent study would be Lucas(2000) and this is his conclusion (see below).

I did, & it does have a point. However, other papers both cite Lucas 2000 & describe the gastroliths of Seismosaurus (among other sauropods) as having withstood "rigorous testing" (E.g. Cerda 2008: http://www.app.pan.pl/archive/published/app53/app53-351.pdf ). It's also worth mentioning that Lucas 2000 ignores at least 1 of said sauropods.