One of my pet peeves is the cavalier attitude many dinosaur paleontologists have recently in regard to the priority and validity of old taxa. Whether it's lazy dismissal of genera as nomina dubia without an analysis showing this is true, dumping family-level names based on supposed nomina dubia despite the ICZN having no rules about this, making up new definitions for established clades, or just plain old replacement of clade names because the eponymous genus isn't as complete or deeply nested as another. If this trend continues, we may face the following horrifying vision of the future...
Theropoda
- Coelophysoidea (based on a complete neotype for Coelophysis bauri, the only known material for the first 66 years having been ignored as archosaur scrap; IT'S ALREADY TRUE!)
- Sinodilophosauridae (people still refuse to use Dilophosauridae, but the describers of what was originally Dilophosaurus sinensis came up with their own name for this clade)
- Averostra (because enough people misused Bakker's Neotheropoda so that they forgot he created it for this node and started using a term published 16 years later instead)
-- Ceratosauria
--- Majungasauroidea (Abelisaurus was deemed too fragmentary, and Carnotaurus is still only known from one specimen. Majungasaurus itself is now based on a complete neotype found in 2068)
---- Masiakasauridae
---- Majungasauridae
-- Tetanuriformes (someone finally got enough followers after redefining Tetanurae to be less inclusive, thus Tetanurae has different meanings depending on what year a paper was published)
--- Suchomimia
---- Tayntonsauridae (after a incomplete articulated megalosaur was found in Megalosaurus' type beds, it was named to 'solve' the confusion surrounding Megalosaurus' association. All Megalosaurus remains were then referred to Tayntonsaurus)
---- Suchomimidae (Yes, ignoring Spinosauridae, Baryonychidae, Irritatoridae and Cristatusaurus)
--- Tetanurae
----Sinraptoroidea (after Allosaurus fragilis was shown to be a nomen dubium, people incorrectly said a family level name couldn't be based on it)
----- Sinraptoridae (no comment needed)
----- Neoallosauridae (people declared Allosaurus, Labrosaurus, Creosaurus and Epanterias to be undiagnostic in a footnote of the paper describing Big Al as Neoallosaurus in 2035)
----- Carcharodontosauria
------ Neovenatoridae
------ Acrocanthosauridae
------ Shaochilongidae
------ Tyrannotitanidae
------ Carcharodontosauridae (ignoring the stable stem-based definition of Carcharodontosauridae, people kept redefining it to be less and less inclusive)
---- Tyrannosauroidea (despite including the following two families, both named prior to Tyrannosauridae...)
----- Coeluridae
----- Compsognathidae
----- Tyrannosauridae
---- Avesternes (someone named it in 2019 and people started to ignore Maniraptoriformes)
----- Ornithomimosauria (based on a neotype for Ornithomimus edmontonicus, even though O. velox was the type species and brevitertius has priority over edmontonicus)
----- Eunothronychia (Therizinosauria was defeated the same way it gained usage, once graffami was given its own genus)
----- Citipatia (Oviraptor was too fragmentary, so the clade was renamed once Citipati's holotype was fully described in 2023. IGM 100/42 remains undescribed and called the Zamyn Kondt oviraptorid as of 2100)
----- Bimedicamentodontidae (Troodon is a long forgotten name, and no the family hasn't been subdivided yet despite there being 73 described diagnostic genera)
----- Dromaeosauridae (miraculously unaffected, but Barsbold's estate owns Adasaurus, which no one is allowed to circulate holograms of)
----- Shuvuuiformes (because of... well, you get the drift by now)
----- Birdia (we finally got sick of the semantic arguments)
Only you can prevent this terrifying prediction from becoming reality. Support priority, follow the ICZN until another code is viable (the Phylocode remains unofficial as of 2100, but rumors are Phylonyms is almost complete and that it will start as of 1-1-21xx), and remember a named taxon is valid until shown otherwise by a detailed redescription and comparison.
Saturday, October 15, 2011
Saturday, September 17, 2011
Planet Dinosaur Review
Since I reviewed Dinosaur Revolution, I might as well tackle the other big dino documentary that came out this month. As with Dinosaur Revolution, this review only covers the first episode, which in this case was about Cenomanian North Africa.
Planet Dinosaur's special effects range from decent to sad. While I could go on about the little details like Ouranosaurus chewing like a mammal, having depressions where its laterotemporal fenestrae are, Microraptor lacking primaries attached to its second finger and having wings which are too short, etc., the simple truth is that the dinosaurs are less accurate and less believable as real objects. The maniraptorans (Troodon, Microraptor, Epidexipteryx) are especially poor. That's not to say it's all bad. The Rugops (possibly an Aucasaurus from the Auca Mahuevo episode) and Sarcosuchus look pretty good, the Spinosaurus is decent except for its short tail, and the Ouranosaurus dying had nice motions and rapid breathing. Seeing this show really made me realize how good the models and animation were in Dinosaur Revolution though. It's such a shame the talent/money spent on the latter couldn't have been used for a program like Planet Dinosaur.
As far as behavior goes, it was refreshing to see dinosaurs acting like dinosaurs. There are a few stupid things, like Spinosaurus eating part of a fish, then leaving to catch more ("with prey plentiful, Spinosaurus can afford to be wasteful"). Or Rugops' subsequent portrayal as an obligate scavenger. Or Spinosaurus slashing the fish with its hands, only to eat tiny bits at a time. But at least nothing they do is human-like. The behavior is largely defended by reference to actual studies (see below), and the show does a good job of making a story based on these. The larger narrative of Spinosaurus being the largest and last spinosaurid and dying from climate change was flawed because Late Cretaceous African dinosaurs are poorly known, and Hone et al. (2010) and Candeiro et al. (2004) described Santonian spinosaurids. But Candeiro et al.'s conclusion was doubted in their 2006 paper and Hone et al.'s study is quite new. Bearing in mind I don't know how accurate the paleoclimatology was, the larger story felt more plausible than Dinosaur Revolution's apparently tacked-on story of how dinosaur parenting helped their success.
My favorite part of Planet Dinosaur is that it manages to explicitly incorporate numerous journal articles. These are shown in informational panels with the year of publication, age, country, and figures from the original articles or photos of specimens referenced by them. They even managed to rotate one of Stromer's Spinosaurus vertebra drawings in 3D, haha. We have Stromer (1915), Dal Sasso et al. (2005), Amiot et al. (2010), Dal Sasso et al. (2009), Sereno et al. (1996), Tanke and Currie (2000), Sereno et al. (2008), Kellner (2004), Charig and Milner (1986), and a biomechanical strength analysis of Carcharodontosaurus' jaws. I don't know how much I agree with some of the conclusions (like amphibious spinosaurids), but at least they're actually from the scientific literature and not just random made-up possibilities.
There are ocassional errors, like overlaying a tyrannosaurid dentary on Sinraptor's skull, or using Stromer's reconstruction as the basis of the Spinosaurus skeletal, resulting in one of the worst reconstructions I've seen. It's good they knew to tilt it horizontal and give it the right skull, but the anatomy! Sacral neural spines lateral to the ilium, the femur articulating with the postacetabular process, two sets of pubes... I could insult it all day.
And yet other details of their informational panels are accurate, such as Irritator and Siamosaurus being inconspicuously listed as additional spinosaurids on the map. Overall, it's quite good. I actually learned what Onchopristis was, and that there's a partial Spinosaurus maxilla with an Onchopristis tooth embedded in it (not just MSNM V4047 with its embedded vertebra). There's also apparently a Spinosaurus neural spine found in 2008 in Morocco that had been broken in life, which I had never heard of. Any time a dinosaur show manages to teach ME something, I'm impressed.
So I quite liked Planet Dinosaur. It's almost the exact opposite of Dinosaur Revolution- generally inaccurate restorations behaving fairly realistically, packed full of references to specific discoveries in the literature, telling us what we know and why. I'll be watching the following episodes, and contra my earlier statement I'll probably tune in to the other Dinosaur Revolutions too. I'll just have to treat the latter like the Transformers 2 of dinosaur programs- pretty to watch, but turn off your brain. On the other hand, I'll be interested to see if Planet Dinosaur presents any more discoveries I hadn't heard of.
Planet Dinosaur's special effects range from decent to sad. While I could go on about the little details like Ouranosaurus chewing like a mammal, having depressions where its laterotemporal fenestrae are, Microraptor lacking primaries attached to its second finger and having wings which are too short, etc., the simple truth is that the dinosaurs are less accurate and less believable as real objects. The maniraptorans (Troodon, Microraptor, Epidexipteryx) are especially poor. That's not to say it's all bad. The Rugops (possibly an Aucasaurus from the Auca Mahuevo episode) and Sarcosuchus look pretty good, the Spinosaurus is decent except for its short tail, and the Ouranosaurus dying had nice motions and rapid breathing. Seeing this show really made me realize how good the models and animation were in Dinosaur Revolution though. It's such a shame the talent/money spent on the latter couldn't have been used for a program like Planet Dinosaur.
As far as behavior goes, it was refreshing to see dinosaurs acting like dinosaurs. There are a few stupid things, like Spinosaurus eating part of a fish, then leaving to catch more ("with prey plentiful, Spinosaurus can afford to be wasteful"). Or Rugops' subsequent portrayal as an obligate scavenger. Or Spinosaurus slashing the fish with its hands, only to eat tiny bits at a time. But at least nothing they do is human-like. The behavior is largely defended by reference to actual studies (see below), and the show does a good job of making a story based on these. The larger narrative of Spinosaurus being the largest and last spinosaurid and dying from climate change was flawed because Late Cretaceous African dinosaurs are poorly known, and Hone et al. (2010) and Candeiro et al. (2004) described Santonian spinosaurids. But Candeiro et al.'s conclusion was doubted in their 2006 paper and Hone et al.'s study is quite new. Bearing in mind I don't know how accurate the paleoclimatology was, the larger story felt more plausible than Dinosaur Revolution's apparently tacked-on story of how dinosaur parenting helped their success.
My favorite part of Planet Dinosaur is that it manages to explicitly incorporate numerous journal articles. These are shown in informational panels with the year of publication, age, country, and figures from the original articles or photos of specimens referenced by them. They even managed to rotate one of Stromer's Spinosaurus vertebra drawings in 3D, haha. We have Stromer (1915), Dal Sasso et al. (2005), Amiot et al. (2010), Dal Sasso et al. (2009), Sereno et al. (1996), Tanke and Currie (2000), Sereno et al. (2008), Kellner (2004), Charig and Milner (1986), and a biomechanical strength analysis of Carcharodontosaurus' jaws. I don't know how much I agree with some of the conclusions (like amphibious spinosaurids), but at least they're actually from the scientific literature and not just random made-up possibilities.
There are ocassional errors, like overlaying a tyrannosaurid dentary on Sinraptor's skull, or using Stromer's reconstruction as the basis of the Spinosaurus skeletal, resulting in one of the worst reconstructions I've seen. It's good they knew to tilt it horizontal and give it the right skull, but the anatomy! Sacral neural spines lateral to the ilium, the femur articulating with the postacetabular process, two sets of pubes... I could insult it all day.
 |
| Please put this travesty out of its misery |
So I quite liked Planet Dinosaur. It's almost the exact opposite of Dinosaur Revolution- generally inaccurate restorations behaving fairly realistically, packed full of references to specific discoveries in the literature, telling us what we know and why. I'll be watching the following episodes, and contra my earlier statement I'll probably tune in to the other Dinosaur Revolutions too. I'll just have to treat the latter like the Transformers 2 of dinosaur programs- pretty to watch, but turn off your brain. On the other hand, I'll be interested to see if Planet Dinosaur presents any more discoveries I hadn't heard of.
Tuesday, September 13, 2011
Dinosaur Revolution review
Well, that was painful. I decided to join the trend and review the show that's been so hyped- Dinosaur Revolution. Little did I know my yearly allowance of eyerolls would be used up. I only watched the frirst episode "Evolution's Winners" and frankly have no desire to sample more.
First the good. The models were usually excellent, with non-pronated hands and all that good stuff. I especially enjoyed the dilophosaurian snouts on the Cryolophosaurus, and the Mongolian mammals which weren't just shrews or mice. I also liked the homage to Dryptosaurus and Ceratosaurus artwork in the Cryolophosaurus section (though I don't think they could really stand on their tails, given how most theropod chevrons look). The Gigantoraptor's feathering was more problematic, as it seemed more like a naked theropod covered in feathers than an actual feathered creature like a bird, where body outlines are hidden and feathers interact and fold. Its wings were always held out in front, which for a display is fine, but even the female who wanders up is posed this way. The animation itself was a mixed bag. Most moved smoothly, but the Saurosuchus looked unnatural for instance. Similarly, the rendering was good for most, but the therapsids in the opening seen looked plasticy. What's that you say? My "good" paragraph's actually mostly full of criticisms? Guess that prepares the way for the rest of the review...
What made Dinosaur Revolution most difficult to watch is the rampant anthropomorphism. Basically none of the subjects actually behaves like a reptile, or a bird, or even a non-ape mammal for that matter. They're chock full of human mannerisms. You can always tell what they're supposed to be feeling, as if brains that size could even house such emotion. But it's not just behavior. My jaw dropped at the blatant 'sexy eyelash' marks on the female Eoraptors. Why not just go the whole hog and give them real eyelashes they can flutter alluringly? Then the male's heart (shaped like a heart of course) could project from its chest like a piston. Would have been almost as realistic as the expectant smile he shows as she approaches in the actual program. Even ignoring the behavior, the plotlines have so many "entertaining" improbable portions, like the Eoraptor unwittingly throwing a therapsid into Saurosuchus' mouth, that any illusion you're watching reality is destroyed. And what was up with that swarm of hostile flies chasing the Antarctic fauna and killing the lizard... for blood! Is this a 1950s horror movie or something?
Which would have all been excusable if the show at least taught us something. Then it'd be a Dinosaur Train for adults, which wouldn't be my idea of a good program to watch, but would at least educate the part of the public that finds documentaries boring. But no, I don't think there was any actual paleontological data contained in that hour, besides most of the portrayed anatomy and a few basic facts like "birds are dinosaurs" and "Cryolophosaurus is from Antarctica". I say "most" because while the models were largely accurate, they sometimes contained some fictional aspect. The rhamphorhynchoid tail fin on the female Eoraptors, for instance. Or the highly elaborate wattles and soft horns on the male Gigantoraptor. And when it comes to behavior, we have bower-building Eoraptors, color flushing Cryolophosaurus which killed the young of rival males, a stomping and twirling Gigantoraptor mating dance, Glacialisaurus which lived in harems (which we so know from the partial hindlimb...), etc. It's not that these soft parts or behaviors are impossible, but Joe Public's only going to remember Gigantoraptor as "that goofy rainbow-colored thing that dances" or Eoraptor as "those raptors that cutely chirp and build mounds to select mates, and then care for their baby who adorably falls down, awwww". So you're emphasizing the fictional aspects of these animals, while not going into any of the actual known interesting facts about them.
But maybe the show could have retained some use if all of this human-like/fictional appearance and behavior was there to illustrate some greater true scientific fact, that even network execs think viewers could remember. Alas, no. The implication of the Eoraptor portion was that dinosaur success was due to more complex parental care, but my impression has been that evidence for such care is limited to maniraptorans, supposed evidence for care in hadrosaurs (and thus Ornithischia) has been refuted, and that baby sauropods were too small to associate with adults and aren't apparent in herd trackways. And even the mosasaur cares for its babies enough to get revenge on sharks for eating them (vengeance is such a widespread trait in squamates...). As does the Cretaceous mammal, more realistically. If you want to make the point dinosaurs were probably often brightly colored with display structures as the Gigantoraptor portion tries to, a far superior method would be to show say ten different possibilities for a few species in quick succession. Changing colors and adding wattles wouldn't be that resource intensitive and would get the idea across to laymen without making it seem like we know they had definite soft features and patterns (I'm guessing the Yixian pigments were unknown when this was made). The Cryolophosaurus portion taught us about the factual behavior... of lions. The mosasaur segment taught us... er... "a mother's protective instinct is a force of nature than can change the world." And the Glacialisaurus one taught us "a little bad luck goes a long way." That's certainly scientific. Maybe the next episode will teach us "the disadvantaged underdog can succeed with perseverance and faith in himself." Sigh
To sum up, watch if you like largely accurate-looking dinosaurs acting like humans in zany situations and learning valuable life lessons. If you want a show that clearly indicates which parts are based on paleontology, shows dinosaurs as they may have been, and teaches you something about them, keep dreaming.
First the good. The models were usually excellent, with non-pronated hands and all that good stuff. I especially enjoyed the dilophosaurian snouts on the Cryolophosaurus, and the Mongolian mammals which weren't just shrews or mice. I also liked the homage to Dryptosaurus and Ceratosaurus artwork in the Cryolophosaurus section (though I don't think they could really stand on their tails, given how most theropod chevrons look). The Gigantoraptor's feathering was more problematic, as it seemed more like a naked theropod covered in feathers than an actual feathered creature like a bird, where body outlines are hidden and feathers interact and fold. Its wings were always held out in front, which for a display is fine, but even the female who wanders up is posed this way. The animation itself was a mixed bag. Most moved smoothly, but the Saurosuchus looked unnatural for instance. Similarly, the rendering was good for most, but the therapsids in the opening seen looked plasticy. What's that you say? My "good" paragraph's actually mostly full of criticisms? Guess that prepares the way for the rest of the review...
What made Dinosaur Revolution most difficult to watch is the rampant anthropomorphism. Basically none of the subjects actually behaves like a reptile, or a bird, or even a non-ape mammal for that matter. They're chock full of human mannerisms. You can always tell what they're supposed to be feeling, as if brains that size could even house such emotion. But it's not just behavior. My jaw dropped at the blatant 'sexy eyelash' marks on the female Eoraptors. Why not just go the whole hog and give them real eyelashes they can flutter alluringly? Then the male's heart (shaped like a heart of course) could project from its chest like a piston. Would have been almost as realistic as the expectant smile he shows as she approaches in the actual program. Even ignoring the behavior, the plotlines have so many "entertaining" improbable portions, like the Eoraptor unwittingly throwing a therapsid into Saurosuchus' mouth, that any illusion you're watching reality is destroyed. And what was up with that swarm of hostile flies chasing the Antarctic fauna and killing the lizard... for blood! Is this a 1950s horror movie or something?
Which would have all been excusable if the show at least taught us something. Then it'd be a Dinosaur Train for adults, which wouldn't be my idea of a good program to watch, but would at least educate the part of the public that finds documentaries boring. But no, I don't think there was any actual paleontological data contained in that hour, besides most of the portrayed anatomy and a few basic facts like "birds are dinosaurs" and "Cryolophosaurus is from Antarctica". I say "most" because while the models were largely accurate, they sometimes contained some fictional aspect. The rhamphorhynchoid tail fin on the female Eoraptors, for instance. Or the highly elaborate wattles and soft horns on the male Gigantoraptor. And when it comes to behavior, we have bower-building Eoraptors, color flushing Cryolophosaurus which killed the young of rival males, a stomping and twirling Gigantoraptor mating dance, Glacialisaurus which lived in harems (which we so know from the partial hindlimb...), etc. It's not that these soft parts or behaviors are impossible, but Joe Public's only going to remember Gigantoraptor as "that goofy rainbow-colored thing that dances" or Eoraptor as "those raptors that cutely chirp and build mounds to select mates, and then care for their baby who adorably falls down, awwww". So you're emphasizing the fictional aspects of these animals, while not going into any of the actual known interesting facts about them.
But maybe the show could have retained some use if all of this human-like/fictional appearance and behavior was there to illustrate some greater true scientific fact, that even network execs think viewers could remember. Alas, no. The implication of the Eoraptor portion was that dinosaur success was due to more complex parental care, but my impression has been that evidence for such care is limited to maniraptorans, supposed evidence for care in hadrosaurs (and thus Ornithischia) has been refuted, and that baby sauropods were too small to associate with adults and aren't apparent in herd trackways. And even the mosasaur cares for its babies enough to get revenge on sharks for eating them (vengeance is such a widespread trait in squamates...). As does the Cretaceous mammal, more realistically. If you want to make the point dinosaurs were probably often brightly colored with display structures as the Gigantoraptor portion tries to, a far superior method would be to show say ten different possibilities for a few species in quick succession. Changing colors and adding wattles wouldn't be that resource intensitive and would get the idea across to laymen without making it seem like we know they had definite soft features and patterns (I'm guessing the Yixian pigments were unknown when this was made). The Cryolophosaurus portion taught us about the factual behavior... of lions. The mosasaur segment taught us... er... "a mother's protective instinct is a force of nature than can change the world." And the Glacialisaurus one taught us "a little bad luck goes a long way." That's certainly scientific. Maybe the next episode will teach us "the disadvantaged underdog can succeed with perseverance and faith in himself." Sigh
To sum up, watch if you like largely accurate-looking dinosaurs acting like humans in zany situations and learning valuable life lessons. If you want a show that clearly indicates which parts are based on paleontology, shows dinosaurs as they may have been, and teaches you something about them, keep dreaming.
Friday, September 9, 2011
Tehuelchesaurus and how to describe the affinities of a taxon
I've often complained about the tendency for authors to view their most parsimonious cladogram as "the right" tree, such as here and here. I note that it's usually more helpful to describe how parsimonious different hypotheses are, since while new analyses usually change the topology somewhat, they rarely support relationships that were strongly rejected before. Carballido et al. (2011) recently redescribed the sauropod Tehuelchesaurus, and in addition to a detailed osteology and several other important discussions, their paper contains a phylogenetic analysis that did things just the way they should. The analysis (249 characters, 45 taxa) is based on Wilson's (2002) analysis with added data, including numerous newly added macronarians. Some characters were ordered, taxa which cause polytomies were deleted a posteriori, and Tehuelchesaurus emerged as a basal camarasauromorph sister to Galveosaurus, not a relative of Omeisaurus as originally thought by Rich et al. (1999). But instead of simply letting the matter rest there, Carballido et al. included the section "Testing Alternative Positions for Tehuelchesaurus." Music to my ears. They tested not only the Omeisaurus alternative (9 steps longer), but also positions slightly more (1 step longer) and less (2 steps longer) than Galveosaurus, and noted the character support for all of these. In addition, the authors wrote the following which basically covers any plausible position-
"Other positions within basal camarasauromorphs (in any position within the Janenschia/Tastavinsaurus clade, as sister taxon to Europasaurus, more basal than Europasaurus, and as sister taxon to Camarasaurus) and as a macronarian outside Camarasauromorpha, but more derived than Haplocanthosaurus, require three additional steps. Placing Tehuelchesaurus as sister taxon of Haplocanthosaurus results in a suboptimal tree four steps longer than the MPTs, and as the most basal macronarian needs even five additional steps. Even more steps are required to place this taxon in the Titanosauriformes (seven additional steps as a basal somphospondyl and eight additional steps as a basal brachiosaurid).
Any position outside Macronaria also results in considerably suboptimal tree lengths. Five additional steps are needed to make Tehuelchesaurus the most basal diplodocoid, but any position within higher diplodocoids results in trees that are at least ten steps longer than the MPTs. Likewise, placing Tehuelchesaurus outside Neosauropoda requires six additional steps, and any placement among basal, nonneosauropodan taxa results in trees at least nine steps longer than the MPTs. Thus, the possibility of a Jurassic Patagonian clade of sauropods, including Patagosaurus and Tehuelchesaurus, can also be rejected, as it requires 12 additional steps."
The paper succeeds in giving you a much clearer idea of Tehuelchesaurus' relationships than any one cladogram could. Anybody describing a new taxon should follow their example.
Carballido, Rauhut, Pol and Salgado, 2011. Osteology and phylogenetic relationships of Tehuelchesaurus benitezii (Dinosauria, Sauropoda) from the Upper Jurassic of Patagonia. Zoological Journal of the Linnean Society. DOI: 10.1111/j.1096-3642.2011.00723.x
"Other positions within basal camarasauromorphs (in any position within the Janenschia/Tastavinsaurus clade, as sister taxon to Europasaurus, more basal than Europasaurus, and as sister taxon to Camarasaurus) and as a macronarian outside Camarasauromorpha, but more derived than Haplocanthosaurus, require three additional steps. Placing Tehuelchesaurus as sister taxon of Haplocanthosaurus results in a suboptimal tree four steps longer than the MPTs, and as the most basal macronarian needs even five additional steps. Even more steps are required to place this taxon in the Titanosauriformes (seven additional steps as a basal somphospondyl and eight additional steps as a basal brachiosaurid).
Any position outside Macronaria also results in considerably suboptimal tree lengths. Five additional steps are needed to make Tehuelchesaurus the most basal diplodocoid, but any position within higher diplodocoids results in trees that are at least ten steps longer than the MPTs. Likewise, placing Tehuelchesaurus outside Neosauropoda requires six additional steps, and any placement among basal, nonneosauropodan taxa results in trees at least nine steps longer than the MPTs. Thus, the possibility of a Jurassic Patagonian clade of sauropods, including Patagosaurus and Tehuelchesaurus, can also be rejected, as it requires 12 additional steps."
The paper succeeds in giving you a much clearer idea of Tehuelchesaurus' relationships than any one cladogram could. Anybody describing a new taxon should follow their example.
Carballido, Rauhut, Pol and Salgado, 2011. Osteology and phylogenetic relationships of Tehuelchesaurus benitezii (Dinosauria, Sauropoda) from the Upper Jurassic of Patagonia. Zoological Journal of the Linnean Society. DOI: 10.1111/j.1096-3642.2011.00723.x
Wednesday, August 17, 2011
Do we have dromaeosaurid evolution backwards?
The basic evolution of Maniraptora has seemed pretty well established in the past decade, thanks to TWG papers describing Sinovenator, Mei, Mahakala, Xiaotingia and such. The basal paravian was a little bird-like taxon, like Microraptor on the dromaeosaurid end or Jinfengopteryx on the troodontid end, with genera like Rahonavis and Anchiornis breaking the boundaries even more. Going further towards the base of Maniraptora, the cranial similarities between scansoriopterygids and basal oviraptorosaurs have suggested a short-snouted herbivorous ancestor, while Shuvuuia and Pelecanimimus have similar skulls that suggest the first maniraptoriform was not a macropredator. Large, more obviously carnivorous taxa like eudromaeosaurs are seen as reversals to a more traditional theropod lifestyle. It's a nice story and may be right, but what if it's wrong?
Dromaeosaurid morphology forms a continuum from the extreme of Achillobator with its deep snout, mesially serrated teeth, low DSDI, rather short coracoid, posteriorly facing glenoid, relatively short arms, deep brevis fossa, large anterior pubic boot and proximally placed obturator process, though Deinonychus, Velociraptor, Bambiraptor, Sinornithosaurus, Microraptor, Buitreraptor/Unenlagia and ending at Rahonavis. Even if the unenlagiines are avialans though, dromaeosaurids need a lot of reversals no matter which direction evolution went. Note that stratigraphy doesn't strongly support either option. We have Utahraptor from the Barremian which is very similar to Achillobator, and dromaeosaurid-like teeth with mesial serrations resembling both dromaeosaurines and velociraptorines in the Late Jurassic. Then again, there's the microraptorian-like Graciliraptor and Shanag which also lived early, and the possible microraptorian "Paleopteryx" from the Morrison.
There's also a possible transitional form between basal coelurosaurs and dromaeosaurids- Ornitholestes. Like dromaeosaurids, Ornitholestes has a third premaxillary tooth much smaller than the first two, short cervical vertebrae with tall neural spines, prominent anterior cervical epipophyses, a crest-like ventral tuberosity on the humerus, an enlarged second pedal ungual and a transversely expanded metatarsal IV. It's also similar to paravians in the elongate distal caudals and bifurcated chevrons. Deriving dromaeosaurids from something of Ornitholestes-grade would explain why they are almost unique among derived maniraptorans in having prefrontals, which unlike the dental characters of eudromaeosaurs, are not plausibly due to macropredatory habits. In this scenario, microraptorians would be convergent with birds in their aerial characters.
Is there any other evidence for this idea? Don't troodontids show the same pattern as dromaeosaurids, going from Jinfengopteryx/Anchiornis to Mei/Sinovenator to Sinornithoides/Byronosaurus to Troodon? Maybe not. Jinfengopteryx and Anchiornis can switch to Avialae easily, and the same may be true for Mei and Sinovenator. They're often avialans in the in progress Lori matrix, even with Xu et al.'s troodontid characters. Lori itself emerged sister to Sinornithoides in Hartman et al.'s SVP poster and is Jurassic in age, with serrated teeth. Maybe that's the basal grade for troodontids, and birds are related but evolved serrationless teeth, long arms, dorsal ischial processes and such on their own branch.
The Jurassic Haplocheirus also supports this idea, since it shows serrated teeth and a general morphology so primitive that Cau's Sumrukia matrix found it to clade with compsognathids. Note therizinosaurs also have mesial and distal serrations, and that Falcarius has made the clade more basal in most matrices, unlike earlier ideas they were related to oviraptorosaurs. Maybe coelurosaurs were of the compsognathid-coelurid grade all through their evolution, with ornithomimosaurs, alvarezsaurids, therizinosaurs, dromaeosaurids and troodontids+birds each developing their birdlike and/or herbivorous characters separately. This idea is kind of anti-Paulian or anti-BCF in nature and has plenty of precedent in the literature. Ostrom long suggested Ornitholestes as a dromaeosaurid ancestor, and Makovicky (1995) found the two to be sister taxa to the exclusion of birds based on vertebral characters.
Of course the real test is with cladistic analyses, so how does the idea fare? The in progress Lori matrix finds a fairly traditional tree with Ornitholestes sister to Maniraptoriformes, microraptorians and Unenlagia basal among dromaeosaurids, and is somewhat unusual in finding troodontids sister to birds. Constraining Ornitholestes to be a dromaeosaurid and the dromaeosaurid topology 'backwards' from the consensus (Achillobator,Dromaeosaurus(Deinonychus,Velociraptor(Microraptor,Sinornithosaurus))) results in trees 11 steps longer. Not too bad when you consider enforcing Longrich and Currie's (2009) plausible-seeming traditional dromaeosaurid topology is 7 steps longer than the minimum.
Dromaeosaurid morphology forms a continuum from the extreme of Achillobator with its deep snout, mesially serrated teeth, low DSDI, rather short coracoid, posteriorly facing glenoid, relatively short arms, deep brevis fossa, large anterior pubic boot and proximally placed obturator process, though Deinonychus, Velociraptor, Bambiraptor, Sinornithosaurus, Microraptor, Buitreraptor/Unenlagia and ending at Rahonavis. Even if the unenlagiines are avialans though, dromaeosaurids need a lot of reversals no matter which direction evolution went. Note that stratigraphy doesn't strongly support either option. We have Utahraptor from the Barremian which is very similar to Achillobator, and dromaeosaurid-like teeth with mesial serrations resembling both dromaeosaurines and velociraptorines in the Late Jurassic. Then again, there's the microraptorian-like Graciliraptor and Shanag which also lived early, and the possible microraptorian "Paleopteryx" from the Morrison.
There's also a possible transitional form between basal coelurosaurs and dromaeosaurids- Ornitholestes. Like dromaeosaurids, Ornitholestes has a third premaxillary tooth much smaller than the first two, short cervical vertebrae with tall neural spines, prominent anterior cervical epipophyses, a crest-like ventral tuberosity on the humerus, an enlarged second pedal ungual and a transversely expanded metatarsal IV. It's also similar to paravians in the elongate distal caudals and bifurcated chevrons. Deriving dromaeosaurids from something of Ornitholestes-grade would explain why they are almost unique among derived maniraptorans in having prefrontals, which unlike the dental characters of eudromaeosaurs, are not plausibly due to macropredatory habits. In this scenario, microraptorians would be convergent with birds in their aerial characters.
Is there any other evidence for this idea? Don't troodontids show the same pattern as dromaeosaurids, going from Jinfengopteryx/Anchiornis to Mei/Sinovenator to Sinornithoides/Byronosaurus to Troodon? Maybe not. Jinfengopteryx and Anchiornis can switch to Avialae easily, and the same may be true for Mei and Sinovenator. They're often avialans in the in progress Lori matrix, even with Xu et al.'s troodontid characters. Lori itself emerged sister to Sinornithoides in Hartman et al.'s SVP poster and is Jurassic in age, with serrated teeth. Maybe that's the basal grade for troodontids, and birds are related but evolved serrationless teeth, long arms, dorsal ischial processes and such on their own branch.
The Jurassic Haplocheirus also supports this idea, since it shows serrated teeth and a general morphology so primitive that Cau's Sumrukia matrix found it to clade with compsognathids. Note therizinosaurs also have mesial and distal serrations, and that Falcarius has made the clade more basal in most matrices, unlike earlier ideas they were related to oviraptorosaurs. Maybe coelurosaurs were of the compsognathid-coelurid grade all through their evolution, with ornithomimosaurs, alvarezsaurids, therizinosaurs, dromaeosaurids and troodontids+birds each developing their birdlike and/or herbivorous characters separately. This idea is kind of anti-Paulian or anti-BCF in nature and has plenty of precedent in the literature. Ostrom long suggested Ornitholestes as a dromaeosaurid ancestor, and Makovicky (1995) found the two to be sister taxa to the exclusion of birds based on vertebral characters.
Of course the real test is with cladistic analyses, so how does the idea fare? The in progress Lori matrix finds a fairly traditional tree with Ornitholestes sister to Maniraptoriformes, microraptorians and Unenlagia basal among dromaeosaurids, and is somewhat unusual in finding troodontids sister to birds. Constraining Ornitholestes to be a dromaeosaurid and the dromaeosaurid topology 'backwards' from the consensus (Achillobator,Dromaeosaurus(Deinonychus,Velociraptor(Microraptor,Sinornithosaurus))) results in trees 11 steps longer. Not too bad when you consider enforcing Longrich and Currie's (2009) plausible-seeming traditional dromaeosaurid topology is 7 steps longer than the minimum.
Tuesday, August 9, 2011
And the best paper written about a theropod is...
I'm sure I can come across as a grumpy old carmudgeon thanks to my frequent criticisms of papers, even good ones like Benson et al. (2011). Critiquing is fun and I think more important than praise when it comes to scientific papers, but for a change, here's a paper I was floored by.
I was lucky enough to be sent a copy of Dal Sasso and Maganuco's new Scipionyx monograph, and boy does it deliver! Scipionyx is one of those Science/Nature taxa that's initially described in two pages with a couple figures, then goes for years until a decent description comes out (See how I work criticism into even an article designed to praise, heh. Btw, of that list, Enantiornis has since been redescribed, and papers on Guanlong, Buitreraptor and Haplocheirus are in the works. Woo!) Luckily, the illustrations in Dal Sasso and Signore's 1998 paper were superb and covered all the material, so waiting wasn't as painful as it is for some other taxa. Even so, if every 'tabloid taxon' were given this good of a treatment once they were redescribed, I'd have no complaint waiting a decade for them. The monograph is simply unparalleled in every aspect. Quality diagnosis of autapomorphies. Huge illustrations and color photos, extensive explanatory diagrams, x-rays, ultraviolet, different angles. Measurements of everything. Eleven pages discussing the ontogenetic indicators. A phylogenetic analysis using a good base (Senter's TWG modification), codes taxa completely, has explicit coding changes based on new papers and most relevent taxa included (exceptions are Proceratosaurus and Bagaraatan). Then there's the long description of all the soft parts most taxa don't leave us. And the taphonomy. And the physiology, discussing Ruben's terrible ideas. And the quality reconstructions. And the discussion of diet, given its multiple prey remains. The tome ends with several life restorations, of which my favorite is Riboli's. See, that's why I don't write more glowing reviews- saying "x is good, y is good, etc." just gets repetitive and uninteresting. Sort of like how ancient theologians said much more about the tortures of Hell than the joys of Heaven. ;)
As for negatives, Scipionyx and Orkoraptor are grouped together based on the supposed caudal pleurocoels of the former. Yet those are so small they look more like nutrient foramina to me, which have caused similar confusion in Acrocanthosaurus and some therizinosauroids. But Dal Sasso and Maganuco correctly discuss how the Senter matrix does not include relevent taxa and characters from Benson et al.'s study, and that the latter does not include enough coelurosaur information. Also, I would disagree with a couple coding choices for ontogenetically variable characters in Scipionyx, which are discussed in Appendix 5. But hey, what other papers even mention why they code ontogenetically variable characters in young specimens? So really, even the few problems were elaborated on to the point that I can't count them against the authors. The work is simply a masterpiece.
Anyone who wants to write a description of a theropod, look at what Dal Sasso and Maganuco created, and copy its format and scope to the best of your ability.
Dal Sasso and Maganuco, 2011. Scipionyx samniticus (Theropoda: Compsognathidae) from the Lower Cretaceous of Italy: Osteology, ontogenetic assessment, phylogeny, soft tissue anatomy, taphonomy, and palaeobiology. Memorie della Società Italiana di Scienze Naturali e del Museo Civico di Storia Naturale di Milano. 281 pp.
I was lucky enough to be sent a copy of Dal Sasso and Maganuco's new Scipionyx monograph, and boy does it deliver! Scipionyx is one of those Science/Nature taxa that's initially described in two pages with a couple figures, then goes for years until a decent description comes out (See how I work criticism into even an article designed to praise, heh. Btw, of that list, Enantiornis has since been redescribed, and papers on Guanlong, Buitreraptor and Haplocheirus are in the works. Woo!) Luckily, the illustrations in Dal Sasso and Signore's 1998 paper were superb and covered all the material, so waiting wasn't as painful as it is for some other taxa. Even so, if every 'tabloid taxon' were given this good of a treatment once they were redescribed, I'd have no complaint waiting a decade for them. The monograph is simply unparalleled in every aspect. Quality diagnosis of autapomorphies. Huge illustrations and color photos, extensive explanatory diagrams, x-rays, ultraviolet, different angles. Measurements of everything. Eleven pages discussing the ontogenetic indicators. A phylogenetic analysis using a good base (Senter's TWG modification), codes taxa completely, has explicit coding changes based on new papers and most relevent taxa included (exceptions are Proceratosaurus and Bagaraatan). Then there's the long description of all the soft parts most taxa don't leave us. And the taphonomy. And the physiology, discussing Ruben's terrible ideas. And the quality reconstructions. And the discussion of diet, given its multiple prey remains. The tome ends with several life restorations, of which my favorite is Riboli's. See, that's why I don't write more glowing reviews- saying "x is good, y is good, etc." just gets repetitive and uninteresting. Sort of like how ancient theologians said much more about the tortures of Hell than the joys of Heaven. ;)
As for negatives, Scipionyx and Orkoraptor are grouped together based on the supposed caudal pleurocoels of the former. Yet those are so small they look more like nutrient foramina to me, which have caused similar confusion in Acrocanthosaurus and some therizinosauroids. But Dal Sasso and Maganuco correctly discuss how the Senter matrix does not include relevent taxa and characters from Benson et al.'s study, and that the latter does not include enough coelurosaur information. Also, I would disagree with a couple coding choices for ontogenetically variable characters in Scipionyx, which are discussed in Appendix 5. But hey, what other papers even mention why they code ontogenetically variable characters in young specimens? So really, even the few problems were elaborated on to the point that I can't count them against the authors. The work is simply a masterpiece.
Anyone who wants to write a description of a theropod, look at what Dal Sasso and Maganuco created, and copy its format and scope to the best of your ability.
Dal Sasso and Maganuco, 2011. Scipionyx samniticus (Theropoda: Compsognathidae) from the Lower Cretaceous of Italy: Osteology, ontogenetic assessment, phylogeny, soft tissue anatomy, taphonomy, and palaeobiology. Memorie della Società Italiana di Scienze Naturali e del Museo Civico di Storia Naturale di Milano. 281 pp.
Saturday, August 6, 2011
Pneumatic disappointment
Benson et al. have a new paper out on theropod postcranial pneumaticity which I was extremely excited about, but the paper itself came as quite the disappointment. Not the general conclusions, which I agree with, but the data collection. The abstract reads "We review recent work on the significance of pneumaticity for understanding the biology of extinct ornithodirans, and present detailed new data on the proportion of the skeleton that was pneumatised in 131 non-avian theropods and Archaeopteryx." With supposed pneumatic ilia in Piatnitzkysaurus and others, Buitreraptor's pneumatic furcula, Shixinggia's pneumatic femur and other recent records, examining 131 theropods for postcranial pneumaticity would be quite enlightening. It's one of those features that is easily missed unless looked for, not often described, and rarely apparent in photos or illustrations. This is especially true for coelurosaurs, since most of the reported unusual pneumatic bones have been from them. All of the authors (Benson, Butler, Carrano and O'Connor) have done excellent detailed work before, so my expectations were high.
The meat of the paper is appendix S1, which contains all of the primary data. It's available here for those who are interested. The first problem is that it's all axial, so there goes my hope of getting some real info on how common appendicular pneumaticity is. More disappointing though is that only 12 of the 99 coelurosaurs are coded from seeing real specimens. The rest is all from the literature. Not that I'm one to frown on using literature, since that's where much of my data comes from too. And Benson et al. are usually good at determining which data can be coded from the literature and noting when information is from a figure, data matrix, etc.. But the information is basically what I could (and have) accumulated myself, with a few new additions thanks to personal communications with Balanoff and Brusatte, but then again I have my own sets of unpublished photos and AMNH observations with data not used by Benson et al.. I suppose I should be happy since this backs up my thesis that papers covering many taxa usually rely mostly on the literature and that my own upcoming paper explicitly describing codings in coelurosaurs is comparable in this measure to one written by four professional leaders in the field. But this time I was hoping for something more, akin to what Nesbitt et al. (2009) did for theropod furculae.
Benson, Butler, Carrano and O'Connor, 2011. Air-filled postcranial bones in theropod dinosaurs: Physiological implications and the 'reptile'-bird transition. Biological Reviews. DOI: 10.1111/j.1469-185X.2011.00190.x
The meat of the paper is appendix S1, which contains all of the primary data. It's available here for those who are interested. The first problem is that it's all axial, so there goes my hope of getting some real info on how common appendicular pneumaticity is. More disappointing though is that only 12 of the 99 coelurosaurs are coded from seeing real specimens. The rest is all from the literature. Not that I'm one to frown on using literature, since that's where much of my data comes from too. And Benson et al. are usually good at determining which data can be coded from the literature and noting when information is from a figure, data matrix, etc.. But the information is basically what I could (and have) accumulated myself, with a few new additions thanks to personal communications with Balanoff and Brusatte, but then again I have my own sets of unpublished photos and AMNH observations with data not used by Benson et al.. I suppose I should be happy since this backs up my thesis that papers covering many taxa usually rely mostly on the literature and that my own upcoming paper explicitly describing codings in coelurosaurs is comparable in this measure to one written by four professional leaders in the field. But this time I was hoping for something more, akin to what Nesbitt et al. (2009) did for theropod furculae.
Benson, Butler, Carrano and O'Connor, 2011. Air-filled postcranial bones in theropod dinosaurs: Physiological implications and the 'reptile'-bird transition. Biological Reviews. DOI: 10.1111/j.1469-185X.2011.00190.x
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