Zanno and Makovicky just published a paper (from Zanno's thesis) presenting a quantitative and statistical analysis of the acquisition and distribution of traits associated with herbivory in coelurosaurs. Basically they found that most maniraptoriforms except dromaeosaurids and (at least) derived troodontids weren't hypercarnivores. No big surprise there, but it's an interesting concept to analyze.
On a basic level, I would have liked more evidence the traits used are actually associated with omnivory/herbivory. For instance the bald eagle has several of the characters used-
- decurved anterior dentary, creating anterior gap between jaws.
- ventrally concave dentary.
- dentary exhibits tooth loss.
- premaxilla edentulous.
- mandibular symphysis fused.
- ischium over 66% of pubic length.
- opisthopubic pelvis.
- more than ten cervical vertebrae.
I think it's important to do a statistical study of dentary curvature/concavity, ischial length, cervical number, etc. in living birds to see if a correlation exists before assuming a correlation to study the diets of extinct taxa. An elongate ischium is found in most non-maniraptorans except coelophysids, so its inclusion is especially confusing.
Yet even if we assume the traits correlate with herbivory, there are issues with the data used. In figure 2 Yanornis is shown as having extrinsic evidence of herbivory while Confuciusornis is left with an ambiguous entry. Yet both taxa are known from specimens preserving fish remains, as the supplementary information table S1 correctly indicates. By their rules in table S1, Confuciusornis should be marked as having character 8 (evidence of carnivory: present only) since it has character 7 (vertebrate gut content: present only), which would then make it marked as lacking character 9 (extrinsic evidence of herbivory). Similarly, Yanornis should be marked as having character 8, which would force 9 to be polymorphic since it also preserves direct evidence of herbivory.
There's also more of our friend the incompletely coded matrix. Looking at Confuciusornis and Yanornis for instance since we're already dealing with them, neither is coded as lacking a U-shaped symphysis. Yanornis isn't coded for its unserrated premaxillary teeth, densely packed teeth or short ischium. Strangely, neither characters 1 nor 3 are coded for any taxon in the matrix.
Also, Confuciusornis is miscoded as having a decurved anterodorsal dentary margin, lacking a ventrally displaced mandibular glenoid and having an ischium over 66% of pubic length. It's also coded as lacking an inset dentary tooth row, conical anterior dentary and+or premaxillary teeth, elongate premaxillary teeth, unserrated premaxillary teeth, lanceolate cheek teeth, recurved teeth, ziphodonty, heterodont dentition, procumbant premaxillary teeth or having replacement waves between teeth, but all of these should be inapplicable since it lacks teeth. Yanornis is miscoded as lacking tooth recurvature.
This is out of 31 characters, mind you. So that's 21 wrong codings out of 62. Note too there are unecessary characters such as "dentary exhibits tooth loss", when the list already contains "rostral dentary exhibits tooth loss" and "caudal dentary exhibits tooth loss." Also "rostral teeth (premaxillary or dentary) conical to subconical" when it contains "premaxillary teeth conical or subconical (e.g., “incisiform”)" and "rostralmost dentary teeth conical: absent (0), present (1)."
So while I don't doubt the general observation that maniraptoriforms were more herbivorous than most other theropods, I'm skeptical of the character distributions and statistics.
Reference- Zanno and Makovicky, 2010. Herbivorous ecomorphology and specialization patterns in theropod dinosaur evolution. PNAS Early Edition. 6 pp. doi 10.1073/pnas.1011924108
Monday, December 20, 2010
Thursday, December 16, 2010
Adventures in Not Coding- Marasuchus by Smith et al.
I've complained about the recent trend to not code taxa for characters in phylogenetic analyses here before. Today I thought I'd show you an example.
The paper is Smith et al.'s (2007) influential basal theropod analysis in the Cryolophosaurus monograph. Holtz said on the DML that it was "truly good stuff, and I strongly suspect that they have better captured the actual phylogeny of basal theropods than most previous studies." The paper includes Makovicky and Currie as coauthors- two people who know their stuff and have access to specimens. There's no excuse to make obvious mistakes.
The taxon is Marasuchus, the outgroup of the analysis. This basal dinosauriform includes the more complete specimens once referred to Lagosuchus and has been described by Bonaparte (1975) and Sereno and Arcucci (1994) in addition to the briefer original descriptions by Romer (e.g. 1972). This is a classic OTU for dinosaur analyses, used in papers by Rauhut, Ezcurra, Novas and others. So there's plenty of information on the taxon available in easily accessed journals like JVP.
What follows are Smith et al.'s codings compared to my codings, divided by anatomical section. Note somebody with access to the specimens themselves would be able to code even more than I could.
Cranial
Smith et al.- ?????????? ?????????? ?????????? ?????????? ?????????? ?????????? ?????????? ?????????? ?????????? ???0???00? 00??-???00 ?0???????? ?????????? ?????????? ?
Me- ?0???????? ?????????? ?0?????00- ?0??10???? ?????????? ?????????? ?????????? ?????????? 0????????0 0??????00? 0000-?1?01 ?0???????? ?????????? ?????????? ?
Cranially, Marasuchus is known from a maxilla and braincase. Note the first section of coded characters in my row pertains to the maxilla, which went completely uncoded by Smith et al.. The second section pertains to the braincase, and here I was also able to code more. Altogether Smith et al. coded 9 characters, while I coded 22.
Axial
Smith et al.- ?00?????- ??0?0??0?0 0?00????0? ?????????0 0???-??0?? ?0??????0? ?????
Me- 0110?0--- 0-0?10000- 01000??010 -?00010?00 100?1010?0 0p00000000 00???
Axially, Smith et al.'s laziness really shows. Marasuchus preserves an almost complete vertebral column, yet Smith et al. only coded a few of the characters. What's confusing too is that it's not the obvious characters which were coded. Things like axis, cervical and dorsal pleurocoels absent, and amphicoelous cervical centra should be second nature to code for anyone even vaguely familiar with the taxon, but then there are characters like "cervical prespinal fossa narrow" which WERE coded. Now having a wide prespinal fossa is an abelisaurid character, so nobody describes the state in something like Marasuchus, and Marasuchus' vertebrae have only been illustrated laterally as far as I know (not anteriorly, as you'd need to see the prespinal fossa). It's not that I doubt Marasuchus would have a narrow fossa if examined, but since almost every non-coelurosaur with preserved cervicals is coded for this obscure character, and the matrix certainly doesn't show signs of rigorous coding in general, I'm suspicious. Another issue is that some of the uncoded characters are important to code in Marasuchus, like the absence of hyposphenes or the presence of only two sacrals. Again these are things anyone with even a passing interest in dinosaur origins would be aware of, as they are classic characters excluding it from Saurischia and Dinosauria respectively. Without coding Marasuchus, the state "2 sacrals" is useless, as all other taxa have more (even the miscoded Saturnalia). In the axial area, 17 characters were coded by Smith et al., but 54 could be coded by me.
The two integumentary characters cannot be coded, of course.
Pectoral
Smith et al.- ??? ?????????
Me- ??? 10010?000
In the pectoral girdle, Marasuchus preserves a scapulocoracoid. Smith et al. didn't bother coding it at all. Even obvious characters like the broad scapular blade, which was explicitly noted by Sereno and Arcucci to be an autapomorphy of the taxon. So 0 coded by them, and 8 by me.
Forelimb
Smith et al.- ? ????????0? ?????????? ?????????? ?
Me- 0 00p?000?0? ?????????? ?????????? ?
In the forelimb, Marasuchus preserves a humerus, radius and ulna. Smith et al. bothered to code one character- radius over half humeral length. At least it's an obvious character this time. That's 1 coded by them, and 8 by me.
Pelvic
Smith et al.- ????????? 0??0??1p00 00-00??0?? ?00?00???? ?
Me- 0000010?1 00020p0100 ---00p?000 --00?0?00? 0
Marasuchus preserves an essentially complete pelvis. This situation is rather like the axial skeleton. Again, obvious characters are left uncoded- propubic pelvis, short preacetabular process, no post-obturator notch. And again, some are important. If Marasuchus isn't coded as lacking a brevis fossa, why even have the character? Everything else in the matrix has one (except Confuciusornis, which is nonsensically coded as inapplicable), so without coding Marasuchus the character's useless. Of pelvic characters, Smith et al. code 16 and I code 35.
Hindlimb
Smith et al.- ??0000000 0000001?0? 0?0????000 00000000?0 0000???0?0 00r????
Me- 001000000 000000100- 0000010000 0101000000 0000001100 001?0??
Finally, a decently coded area. There are certainly some absences, like the obvious anteromedially oriented femoral head and absent fibular crest of the tibia, and none of the fibular characters are coded. But overall it looks like someone actually tried in this area. Smith et al. code 38 and I code 53.
In all, Smith et al. coded 81 characters while I coded 180. That leaves 91 characters uncoded. So they only coded 45% of what was possible using the literature, and an even smaller percentage of what's possible with the specimens in hand. You might not think it's important to code the outgroups, but you'd be wrong. The major conclusion of this paper was that Crylophosaurus and other dilophosaurs were closer to neotheropods than coelophysoids, but this depends on having the polarity for characters in basal Avepoda correct. I can tell you now that even though I haven't worked my way through most of the matrix yet, just adding the codings for Marasuchus, Silesaurus and some for Herrerasaurus has changed the results to give a huge polytomy in basal Avepoda between coelophysoids, Zupaysaurus, dilophosaurids and neotheropods. Who knows how that will change though, as I note that "Dilophosaurus" sinensis wasn't coded at all postcranially, for instance.
I'd honestly like to know how this happens. This isn't some obscure foreign paper by ignorant beginners, it's a landmark paper in a high tier journal by experts in the field. Yet what I've described here is unacceptable. If you're publishing a phylogenetic analysis, please code your taxa. If you're reviewing/editing a paper, please check a taxon or two in the matrix. And if you find uncoded taxa, send the paper back. Because coding only half the available data makes the resulting cladogram worthless.
Reference- Smith, Makovicky, Hammer and Currie, 2007. Osteology of Cryolophosaurus ellioti (Dinosauria: Theropoda) from the Early Jurassic of Antarctica and implications for early theropod evolution. Zoological Journal of the Linnean Society. 151, 377-421.
The paper is Smith et al.'s (2007) influential basal theropod analysis in the Cryolophosaurus monograph. Holtz said on the DML that it was "truly good stuff, and I strongly suspect that they have better captured the actual phylogeny of basal theropods than most previous studies." The paper includes Makovicky and Currie as coauthors- two people who know their stuff and have access to specimens. There's no excuse to make obvious mistakes.
The taxon is Marasuchus, the outgroup of the analysis. This basal dinosauriform includes the more complete specimens once referred to Lagosuchus and has been described by Bonaparte (1975) and Sereno and Arcucci (1994) in addition to the briefer original descriptions by Romer (e.g. 1972). This is a classic OTU for dinosaur analyses, used in papers by Rauhut, Ezcurra, Novas and others. So there's plenty of information on the taxon available in easily accessed journals like JVP.
What follows are Smith et al.'s codings compared to my codings, divided by anatomical section. Note somebody with access to the specimens themselves would be able to code even more than I could.
Cranial
Smith et al.- ?????????? ?????????? ?????????? ?????????? ?????????? ?????????? ?????????? ?????????? ?????????? ???0???00? 00??-???00 ?0???????? ?????????? ?????????? ?
Me- ?0???????? ?????????? ?0?????00- ?0??10???? ?????????? ?????????? ?????????? ?????????? 0????????0 0??????00? 0000-?1?01 ?0???????? ?????????? ?????????? ?
Cranially, Marasuchus is known from a maxilla and braincase. Note the first section of coded characters in my row pertains to the maxilla, which went completely uncoded by Smith et al.. The second section pertains to the braincase, and here I was also able to code more. Altogether Smith et al. coded 9 characters, while I coded 22.
Axial
Smith et al.- ?00?????- ??0?0??0?0 0?00????0? ?????????0 0???-??0?? ?0??????0? ?????
Me- 0110?0--- 0-0?10000- 01000??010 -?00010?00 100?1010?0 0p00000000 00???
Axially, Smith et al.'s laziness really shows. Marasuchus preserves an almost complete vertebral column, yet Smith et al. only coded a few of the characters. What's confusing too is that it's not the obvious characters which were coded. Things like axis, cervical and dorsal pleurocoels absent, and amphicoelous cervical centra should be second nature to code for anyone even vaguely familiar with the taxon, but then there are characters like "cervical prespinal fossa narrow" which WERE coded. Now having a wide prespinal fossa is an abelisaurid character, so nobody describes the state in something like Marasuchus, and Marasuchus' vertebrae have only been illustrated laterally as far as I know (not anteriorly, as you'd need to see the prespinal fossa). It's not that I doubt Marasuchus would have a narrow fossa if examined, but since almost every non-coelurosaur with preserved cervicals is coded for this obscure character, and the matrix certainly doesn't show signs of rigorous coding in general, I'm suspicious. Another issue is that some of the uncoded characters are important to code in Marasuchus, like the absence of hyposphenes or the presence of only two sacrals. Again these are things anyone with even a passing interest in dinosaur origins would be aware of, as they are classic characters excluding it from Saurischia and Dinosauria respectively. Without coding Marasuchus, the state "2 sacrals" is useless, as all other taxa have more (even the miscoded Saturnalia). In the axial area, 17 characters were coded by Smith et al., but 54 could be coded by me.
The two integumentary characters cannot be coded, of course.
Pectoral
Smith et al.- ??? ?????????
Me- ??? 10010?000
In the pectoral girdle, Marasuchus preserves a scapulocoracoid. Smith et al. didn't bother coding it at all. Even obvious characters like the broad scapular blade, which was explicitly noted by Sereno and Arcucci to be an autapomorphy of the taxon. So 0 coded by them, and 8 by me.
Forelimb
Smith et al.- ? ????????0? ?????????? ?????????? ?
Me- 0 00p?000?0? ?????????? ?????????? ?
In the forelimb, Marasuchus preserves a humerus, radius and ulna. Smith et al. bothered to code one character- radius over half humeral length. At least it's an obvious character this time. That's 1 coded by them, and 8 by me.
Pelvic
Smith et al.- ????????? 0??0??1p00 00-00??0?? ?00?00???? ?
Me- 0000010?1 00020p0100 ---00p?000 --00?0?00? 0
Marasuchus preserves an essentially complete pelvis. This situation is rather like the axial skeleton. Again, obvious characters are left uncoded- propubic pelvis, short preacetabular process, no post-obturator notch. And again, some are important. If Marasuchus isn't coded as lacking a brevis fossa, why even have the character? Everything else in the matrix has one (except Confuciusornis, which is nonsensically coded as inapplicable), so without coding Marasuchus the character's useless. Of pelvic characters, Smith et al. code 16 and I code 35.
Hindlimb
Smith et al.- ??0000000 0000001?0? 0?0????000 00000000?0 0000???0?0 00r????
Me- 001000000 000000100- 0000010000 0101000000 0000001100 001?0??
Finally, a decently coded area. There are certainly some absences, like the obvious anteromedially oriented femoral head and absent fibular crest of the tibia, and none of the fibular characters are coded. But overall it looks like someone actually tried in this area. Smith et al. code 38 and I code 53.
In all, Smith et al. coded 81 characters while I coded 180. That leaves 91 characters uncoded. So they only coded 45% of what was possible using the literature, and an even smaller percentage of what's possible with the specimens in hand. You might not think it's important to code the outgroups, but you'd be wrong. The major conclusion of this paper was that Crylophosaurus and other dilophosaurs were closer to neotheropods than coelophysoids, but this depends on having the polarity for characters in basal Avepoda correct. I can tell you now that even though I haven't worked my way through most of the matrix yet, just adding the codings for Marasuchus, Silesaurus and some for Herrerasaurus has changed the results to give a huge polytomy in basal Avepoda between coelophysoids, Zupaysaurus, dilophosaurids and neotheropods. Who knows how that will change though, as I note that "Dilophosaurus" sinensis wasn't coded at all postcranially, for instance.
I'd honestly like to know how this happens. This isn't some obscure foreign paper by ignorant beginners, it's a landmark paper in a high tier journal by experts in the field. Yet what I've described here is unacceptable. If you're publishing a phylogenetic analysis, please code your taxa. If you're reviewing/editing a paper, please check a taxon or two in the matrix. And if you find uncoded taxa, send the paper back. Because coding only half the available data makes the resulting cladogram worthless.
Reference- Smith, Makovicky, Hammer and Currie, 2007. Osteology of Cryolophosaurus ellioti (Dinosauria: Theropoda) from the Early Jurassic of Antarctica and implications for early theropod evolution. Zoological Journal of the Linnean Society. 151, 377-421.
Tuesday, December 14, 2010
The Myth of Martinavis
After 28 years, the monograph on Lecho enantiornithines has finally been published (Walker and Dyke, 2009). This follows the shorter paper by Walker et al. (2007), which assigned many Lecho remains to their new genus Martinavis. Now in addition to M. cruzyensis from France and M. vincei from Argentina, we also have M. saltariensis, M. minor and M. whetstonei living alongside M. vincei, plus an unnamed specimen from the US. At first glance, this seems to be an amazing diversity for an enantiornithine genus, but some further digging indicates trouble for Martinavis.
Walker et al.'s diagnosis for Martinavis is sprawling, but most of the characters are just enantiornithine synapomorphies- proximal margin of humerus concave in its central portion, rising both ventrally and dorsally on either side; bicipital crest prominent; ventral surface of bicipital crest bearing a small fossa for muscle attachment; proximally L-shaped humeral head; well-marked depression underneath the proximal head of the humerus; weakly developed distal condyles; flat distal end that is not deflected dorsally.
The pneumotricipital fossa is no wider in vincei, saltariensis or minor than Elbretornis, Enantiornis, Gurilynia, Halimornis or Otogornis, and is narrow in cruzyensis and whetstonei. It is wide in the American specimen KU-NM-37 though.
The lack of a perforated ventral tubercle is plesiomorphic and also present in such taxa as Halimornis and Eoalulavis.
Most enantiornithine deltopectoral crests could be described as "flat and broad", while the stated lack of ventral curvature in the crest is difficult to understand since it projects dorsally in enantiornithines.
The lack of a marked distal angle between the deltopectoral crest and shaft distally is primitive and also seen in such taxa as Eoalulavis, Eocathayornis, Hebeiornis, Otogornis, Pengornis and Cathayornis, but is absent in saltariensis and not determinable in KU-NM-37.
The bicipital crest in cruzyensis and vincei is no smaller than in Gurilynia, while KU-NM-37, minor, saltariensis and whetstonei have large crests.
The bicipital crest is indeed more anteriorly angled in vincei and KU-NM-37 than Elbretornis, Enantiornis, Halimornis or Gurilynia, but is less angled than Elsornis. Supposed Martinavis species minor, saltariensis and whetstonei have less angled crests. The condition in cruzyensis is not illustrated, though stated to be less than vincei at least.
"Ventral margin of bicipital crest small" is a confusing statement, and the ventrally placed bicipital fossa is also present in Elbretornis, Gurilynia and Halimornis while those of M. cruzyensis, saltariensis and minor are anteroventrally placed.
The ventral condyle is as poorly developed in Elbretornis, Elsornis, Eocathayornis, Kizylkumavis and Cathayornis. Note neither this nor the next three characters can be evaluated in minor, whetstonei or KU-NM-37.
Alexornis, Elbretornis, Elsornis, Kizylkumavis and Otogornis lack both scapulotricipital and humerotricipital grooves as well.
The ventral epicondyle is as large and distally projected in Kizylkumavis and probably Alexornis.
A transversely oriented dorsal condyle is present in almost all enantiornithines, even Elbretornis (contra Walker and Dyke)
Walker et al. also included a differential diagnosis, though it repeats some characters of the general diagnosis (anteriorly angled bicipital crest; deltopectoral crest smoothly angled; transversely oriented dorsal condyle) and has another which contradicts the general diagnosis (small entepicondyle). Of the remaining characters, the shaft is actually less gracile than Enantiornis (and most other enantiornithines), not more. A laterally positioned ectepicondyle is present in all enantiornithines. Walker and Dyke do not add further characters to the diagnosis.
In conclusion, species referred to Martinavis do not share any apomorphies not found in numerous other enantiornithines. Worse, the type species lacks two of the supposed diagnostic characters, saltariensis lacks four, both minor and whetstoni lack at least three, and the American specimen lacks at least one. Walker et al. should have really made M. vincei the type species, since it seems most representative. Walker and Dyke refer numerous additional postcranial elements to Martinavis sp. based on size, but since there's no evidence that genus was present in Argentina, it seems best to keep these as Enantiornithes indet.. The small size of some means they probably belonged to minor or whetstonei, while the larger may have belonged to vincei or saltariensis.
Martinavis - The Cathayornis of the Late Cretaceous. ;)
References- Walker, Buffetaut and Dyke, 2007. Large euenantiornithine birds from the Cretaceous of southern France, North America and Argentina. Geological Magazine. 144(6), 977-986.
Walker and Dyke, 2009. Euenantiornithine birds from the Late Cretaceous of El Brete (Argentina). Irish Journal of Earth Sciences. 27, 15-62.
Walker et al.'s diagnosis for Martinavis is sprawling, but most of the characters are just enantiornithine synapomorphies- proximal margin of humerus concave in its central portion, rising both ventrally and dorsally on either side; bicipital crest prominent; ventral surface of bicipital crest bearing a small fossa for muscle attachment; proximally L-shaped humeral head; well-marked depression underneath the proximal head of the humerus; weakly developed distal condyles; flat distal end that is not deflected dorsally.
The pneumotricipital fossa is no wider in vincei, saltariensis or minor than Elbretornis, Enantiornis, Gurilynia, Halimornis or Otogornis, and is narrow in cruzyensis and whetstonei. It is wide in the American specimen KU-NM-37 though.
The lack of a perforated ventral tubercle is plesiomorphic and also present in such taxa as Halimornis and Eoalulavis.
Most enantiornithine deltopectoral crests could be described as "flat and broad", while the stated lack of ventral curvature in the crest is difficult to understand since it projects dorsally in enantiornithines.
The lack of a marked distal angle between the deltopectoral crest and shaft distally is primitive and also seen in such taxa as Eoalulavis, Eocathayornis, Hebeiornis, Otogornis, Pengornis and Cathayornis, but is absent in saltariensis and not determinable in KU-NM-37.
The bicipital crest in cruzyensis and vincei is no smaller than in Gurilynia, while KU-NM-37, minor, saltariensis and whetstonei have large crests.
The bicipital crest is indeed more anteriorly angled in vincei and KU-NM-37 than Elbretornis, Enantiornis, Halimornis or Gurilynia, but is less angled than Elsornis. Supposed Martinavis species minor, saltariensis and whetstonei have less angled crests. The condition in cruzyensis is not illustrated, though stated to be less than vincei at least.
"Ventral margin of bicipital crest small" is a confusing statement, and the ventrally placed bicipital fossa is also present in Elbretornis, Gurilynia and Halimornis while those of M. cruzyensis, saltariensis and minor are anteroventrally placed.
The ventral condyle is as poorly developed in Elbretornis, Elsornis, Eocathayornis, Kizylkumavis and Cathayornis. Note neither this nor the next three characters can be evaluated in minor, whetstonei or KU-NM-37.
Alexornis, Elbretornis, Elsornis, Kizylkumavis and Otogornis lack both scapulotricipital and humerotricipital grooves as well.
The ventral epicondyle is as large and distally projected in Kizylkumavis and probably Alexornis.
A transversely oriented dorsal condyle is present in almost all enantiornithines, even Elbretornis (contra Walker and Dyke)
Walker et al. also included a differential diagnosis, though it repeats some characters of the general diagnosis (anteriorly angled bicipital crest; deltopectoral crest smoothly angled; transversely oriented dorsal condyle) and has another which contradicts the general diagnosis (small entepicondyle). Of the remaining characters, the shaft is actually less gracile than Enantiornis (and most other enantiornithines), not more. A laterally positioned ectepicondyle is present in all enantiornithines. Walker and Dyke do not add further characters to the diagnosis.
In conclusion, species referred to Martinavis do not share any apomorphies not found in numerous other enantiornithines. Worse, the type species lacks two of the supposed diagnostic characters, saltariensis lacks four, both minor and whetstoni lack at least three, and the American specimen lacks at least one. Walker et al. should have really made M. vincei the type species, since it seems most representative. Walker and Dyke refer numerous additional postcranial elements to Martinavis sp. based on size, but since there's no evidence that genus was present in Argentina, it seems best to keep these as Enantiornithes indet.. The small size of some means they probably belonged to minor or whetstonei, while the larger may have belonged to vincei or saltariensis.
Martinavis - The Cathayornis of the Late Cretaceous. ;)
References- Walker, Buffetaut and Dyke, 2007. Large euenantiornithine birds from the Cretaceous of southern France, North America and Argentina. Geological Magazine. 144(6), 977-986.
Walker and Dyke, 2009. Euenantiornithine birds from the Late Cretaceous of El Brete (Argentina). Irish Journal of Earth Sciences. 27, 15-62.
Friday, December 3, 2010
New Theropod Database Update!
This has been a long time coming. The huge news this time is a brand new section- Ex-Theropod Taxa, which will cover all taxa ever thought to be theropods. I'm excited about writing this section because I'm not familiar with most of the taxa until I research them, so I'm learning quite a bit. Far too often, ex-dinosaurs get ignored by both dinosaur experts and whatever group they end up belonging to, leading to only a superficial knowledge of what they are. Ex-theropods which I've previously covered on my blog include Priscavolucris, the Kota bird, Bathygnathus, "Yezosaurus", Rachitrema, Actiosaurus, Patricosaurus, Megalancosaurus, Longisquama, Gwyneddosaurus, Ankistrodon, "Likhoelesaurus", Tanystrosuchus and Arctosaurus. Ex-theropods which have significant entries that haven't made it to the blog includde Coelurosauravus, Spinosuchus, Pneumatoarthrus, Tanystropheus, Teratosaurus? bengalensis, Avalonianus, "Cinizasaurus", "Cryptoraptor", Sinosaurus? "shawanensis", Trialestes, Sinocoelurus, Teyuwasu, Eucoelophysis, Apatodon, "Troodon" isfarensis, Gresslyosaurus, Eucnemesaurus and Gryponyx. I also moved herrerasaurids and other controversial basal saurischians to the ex-theropod page, since it more accurately reflects their position. Among these, Sanjuansaurus was added, and Eoraptor and Herrerasaurus both got huge makeovers.
Okay, but what about theropods themselves? Tawa was finally added, as was Kayentavenator, and the Coelophysis entry was updated. "Coelurosaurus", "Carnosaurus", Concavenator, Zuolong, Machairasaurus, Balaur, Bauxitornis, "Confuciusornis" jianchengensis, Intiornis, Palintropus, Anatalavis, Neogaeornis, Polarornis and Cimolopteryx were added. Rahiolisaurus was updated, and Cathayornis was separated from Sinornis after O'Connor and Dyke (2010).
Finally, I added the evaluations of Perez-Moreno et al.'s (1994) analysis of Pelecanimimus' position, Chiappe and Calvo's (1994) major analysis of bird phylogeny and the massive effort that is Holtz's (1994) famed theropod analysis.
What's in store for the future? Adding Ezcurra's (2010) and Nesbitt et al.'s (2010) data to the saurischian supermatrix which will let me add the character evidence for conflicting hypotheses to the entries of herrerasaurids, Eoraptor, Chindesaurus, Guaibasaurus, etc., evaluating some more modern analyses like Smith et al. (2007) or the TWG matrix, adding more archosaurian ex-theropods, making the cladogram reflect the data better when competing topologies are poorly distinguished by parsimony, and fleshing out entries to include more commentary and characters (both for diagnoses and for alternative placements for taxa).
Okay, but what about theropods themselves? Tawa was finally added, as was Kayentavenator, and the Coelophysis entry was updated. "Coelurosaurus", "Carnosaurus", Concavenator, Zuolong, Machairasaurus, Balaur, Bauxitornis, "Confuciusornis" jianchengensis, Intiornis, Palintropus, Anatalavis, Neogaeornis, Polarornis and Cimolopteryx were added. Rahiolisaurus was updated, and Cathayornis was separated from Sinornis after O'Connor and Dyke (2010).
Finally, I added the evaluations of Perez-Moreno et al.'s (1994) analysis of Pelecanimimus' position, Chiappe and Calvo's (1994) major analysis of bird phylogeny and the massive effort that is Holtz's (1994) famed theropod analysis.
What's in store for the future? Adding Ezcurra's (2010) and Nesbitt et al.'s (2010) data to the saurischian supermatrix which will let me add the character evidence for conflicting hypotheses to the entries of herrerasaurids, Eoraptor, Chindesaurus, Guaibasaurus, etc., evaluating some more modern analyses like Smith et al. (2007) or the TWG matrix, adding more archosaurian ex-theropods, making the cladogram reflect the data better when competing topologies are poorly distinguished by parsimony, and fleshing out entries to include more commentary and characters (both for diagnoses and for alternative placements for taxa).
Thursday, December 2, 2010
Zuolong, a new basal coelurosaur from the Shishugou Formation
No, this isn't the 'important post' alluded to last time, but I had to take advantage of the opportunity to post on a new theropod so soon after it was announced (and before Andrea got to it!). Today we see the publication of Zuolong, or "animal dragon", er... actually it's named after General Zuo Zongtang. Avid theropod fans will know this as the basal coelurosaur skull shown and announced by Clark et al. at SVP 2002. The description is nicely detailed and illustrated, and I look forward to seeing where it ends up in Cau's megamatrix. The phylogenetic analysis is mostly in the supplementary data, so I can't evaluate it, though given Choiniere's past published analyses I'm crossing my fingers that taxa are completely coded this time around. On the positive side, the authors do discuss in detail the alternative placements for basal coelurosaurs which cause the illustrated polytomy, and used a reduced consensus method to prune taxa from the tree a posteriori. Nqwebasaurus was excluded since a redescription is in preparation for the Journal of African Earth Sciences, though I note the Limusaurus analysis found it to be a basal ornithomimosaur. Tugulusaurus was sometimes not a coelurosaur, a result my supermatrix has also found. Bagaraatan was either a tyrannosauroid or an ornithomimosaur. Aniksosaurus was a basal compsognathid. Proceratosaurus could be either a tyrannosauroid, compsognathid or ornithomimosaur, highlighting the caution I've been urging in assigning these small taxa to Tyrannosauroidea. Of course I have no idea what the quality of the matrix is, so I don't know how important those results are. On the negative side, Choiniere is again redefining taxa with "a modified version of the definition of Coelurosauria from Holtz et al. (2004) as all theropods more closely related to birds than to Sinraptor dongi." There's no reason to change the standard Allosaurus external specifier that everyone's used up to this point, not to mention the error everyone else makes in using birds to define Coelurosauria contra Recommendation 11A. In any case, I'm glad to see this description published, and look forward to the upcoming osteologies of Guanlong and Haplocheirus.
Zuolong Choiniere, Clark, Forster and Xu, 2010
Z. salleei Choiniere, Clark, Forster and Xu, 2010
Early Oxfordian, Late Jurassic
Shishugou Formation, Xinjiang, China
Holotype- (IVPP V15912) (~3.1 m; ~35 kg; subadult) incomplete skull, premaxillary tooth, angular, two lateral teeth, partial axial neural arch, incomplete third cervical vertebra, incomplete fourth cervical vertebra, incomplete fifth cervical vertebra, incomplete eighth cervical vertebra, incomplete ninth cervical vertebra, partial tenth cervical neural arch, two dorsal centra, two fragmentary dorsal centra, incomplete sacrum, first caudal neural arch, second caudal neural arch, third caudal centrum, incomplete fourth caudal vertebra, three incomplete mid caudal vertebrae, two mid caudal centra, mid caudal neural arch, incomplete scapula, incomplete humerus, radius (137 mm), incomplete ulna, distal phalanx I-1, incomplete manual ungual I, partial ilium, incomplete pubes, femora (one distal; 336 mm), partial tibia, proximal fibula, partial phalanx I-1, pedal ungual I, metatarsal II (191.9 mm), phalanx II-1, metatarsal III (224.3 mm), partial metatarsal IV (~201.7 mm)
Diagnosis- (after Choiniere et al., 2010) large, slit-like quadrate foramen inclined medially at approximately 45 degrees with associated deep fossa on the quadrate; sacral centrum 5 with an obliquely oriented posterior articular surface that is angled anterodorsally; fovea capitis very large, occupying almost the entire posterodorsal surface of the femoral head; distal condyle of metatarsal III large relative to that of other metatarsals and bearing an anteromedially projecting flange on its anteromedial margin.
Comments- This specimen was discovered in 2001 and announced in an abstract by Clark et al. (2002) as a basal coelurosaur. It was later described in more detail in an abstract by Choiniere et al. (2008), who used a version of the TWG matrix and found it to be one of the most basal coelurosaurs, sister to Tugulusaurus. Choiniere et al. (2010) named and described the taxon in depth, finding it either as a non-tyrannoraptoran coelurosaur in a trichotomy with Tugulusaurus or as a non-maniraptoriform tyrannoraptoran more derived than tyrannosauroids.
References- Clark, Xu, Forster, Wang and Andres, 2002. New small dinosaurs from the Upper Jurassic Shishugou Formation at Wucaiwan, Xinjiang, China. Journal of Vertebrate Paleontology. 22(3), 44A.
Choiniere, Clark, Xu and Forster, 2008. A new basal coelurosaur from the upper Shishugou Formation (Xinjiang, People's Republic of China). Journal of Vertebrate Paleontology. 28(3), 63A.
Choiniere, Clark, Forster and Xu, 2010. A basal coelurosaur (Dinosauria: Theropoda) from the Late Jurassic (Oxfordian) of the Shishugou Formation in Wucaiwan, People's Republic of China. Journal of Vertebrate Paleontology. 30(6), 1773-1796.
 |
| Much of the holotype of Zuolong salleei (IVPP V15912). Note the sacrum plus proximal caudals were shifted in front of the pelvis for viewing purposes, and some elements like the scapula and several partial vertebrae are not shown. Scale = 1 m. (after Choiniere et al., 2010) |
Zuolong Choiniere, Clark, Forster and Xu, 2010
Z. salleei Choiniere, Clark, Forster and Xu, 2010
Early Oxfordian, Late Jurassic
Shishugou Formation, Xinjiang, China
Holotype- (IVPP V15912) (~3.1 m; ~35 kg; subadult) incomplete skull, premaxillary tooth, angular, two lateral teeth, partial axial neural arch, incomplete third cervical vertebra, incomplete fourth cervical vertebra, incomplete fifth cervical vertebra, incomplete eighth cervical vertebra, incomplete ninth cervical vertebra, partial tenth cervical neural arch, two dorsal centra, two fragmentary dorsal centra, incomplete sacrum, first caudal neural arch, second caudal neural arch, third caudal centrum, incomplete fourth caudal vertebra, three incomplete mid caudal vertebrae, two mid caudal centra, mid caudal neural arch, incomplete scapula, incomplete humerus, radius (137 mm), incomplete ulna, distal phalanx I-1, incomplete manual ungual I, partial ilium, incomplete pubes, femora (one distal; 336 mm), partial tibia, proximal fibula, partial phalanx I-1, pedal ungual I, metatarsal II (191.9 mm), phalanx II-1, metatarsal III (224.3 mm), partial metatarsal IV (~201.7 mm)
Diagnosis- (after Choiniere et al., 2010) large, slit-like quadrate foramen inclined medially at approximately 45 degrees with associated deep fossa on the quadrate; sacral centrum 5 with an obliquely oriented posterior articular surface that is angled anterodorsally; fovea capitis very large, occupying almost the entire posterodorsal surface of the femoral head; distal condyle of metatarsal III large relative to that of other metatarsals and bearing an anteromedially projecting flange on its anteromedial margin.
 |
| Skull elements of Zuolong salleei, scaled from figures in Choiniere et al. (2010). Note the squamosal's scale bar in figure 4 is assumed to be 1 cm instead of 3 cm as listed. The mass above the orbit is the frontal and parietal in dorsal view. |
Comments- This specimen was discovered in 2001 and announced in an abstract by Clark et al. (2002) as a basal coelurosaur. It was later described in more detail in an abstract by Choiniere et al. (2008), who used a version of the TWG matrix and found it to be one of the most basal coelurosaurs, sister to Tugulusaurus. Choiniere et al. (2010) named and described the taxon in depth, finding it either as a non-tyrannoraptoran coelurosaur in a trichotomy with Tugulusaurus or as a non-maniraptoriform tyrannoraptoran more derived than tyrannosauroids.
References- Clark, Xu, Forster, Wang and Andres, 2002. New small dinosaurs from the Upper Jurassic Shishugou Formation at Wucaiwan, Xinjiang, China. Journal of Vertebrate Paleontology. 22(3), 44A.
Choiniere, Clark, Xu and Forster, 2008. A new basal coelurosaur from the upper Shishugou Formation (Xinjiang, People's Republic of China). Journal of Vertebrate Paleontology. 28(3), 63A.
Choiniere, Clark, Forster and Xu, 2010. A basal coelurosaur (Dinosauria: Theropoda) from the Late Jurassic (Oxfordian) of the Shishugou Formation in Wucaiwan, People's Republic of China. Journal of Vertebrate Paleontology. 30(6), 1773-1796.
Wednesday, December 1, 2010
"Likhoelesaurus" the mysterious African nomen nudum
Quick update before an important post...
"Likhoelesaurus" Ellenberger, 1970
"L. ingens" Ellenberger, 1970
= "Likhoelesaurus ferox" Ellenberger, 1972
Norian, Late Triassic
Lower Elliot Formation, Lesotho
Material- five teeth (70 mm)
Comments- Ellenberger and Ginsberg (1966) mentioned carnivorous dinosaur teeth from the Lower Elliot Formation, which were later called "Likhoelesaurus ingens" by Ellenberger (1970) and referred to Ornithosuchidae. These were not described properly though, making the name a nomen nudum. Ellenberger (1972) referred to "Likhoelesaurus ferox" as a "giant carnosaur" from zone A/5 of his lower red beds, illustrating five associated recurved teeth in a plate. This was another nomen nudum, with no explanation of the different species name (it may involve Basutodon ferox, but even if "Likhoelesaurus" were officially named, Basutodon would have priority). Kitching and Raath (1984) suggested it may be a junior synonym of Basutodon ferox. It was listed as a teratosaurid theropod by Chure and McIntosh (1989) and a melanorosaurid by Olshevsky (1991). Glut (1997) listed it as ?Theropoda incertae sedis, listed "?bones" among the remains and stated the teeth were 70 mm long. Knoll (2004) discusses the material under Rauisuchia, but notes it could be theropod as well.
With no published description, and only one undetailed photograph, the phylogenetic position of "Likhoelesaurus" remains uncertain. While their recurved morphology excludes referral to Melanorosauridae or any other sauropodomorph clade, differences between the teeth of carnivorous dinosaurs, crutotarsans (including ornithosuchids and teratosaurs) and other carnivorous archosauriforms have yet to be studied. Indeed, they are only assumed to be archosauriform here due to past identifications, since the presence of serrations has not been confirmed. Synonymy with Basutodon is possible, but no shared derived characters have been suggested, Basutodon itself is probably undiagnostic and multiple archosauriform taxa are known from other Late Triassic localities.
References- Ellenberger and Ginsberg, 1966. Le gisement de Dinosauriens triasiques de Maphutseng (Basutoland) et l'origine des Sauropodes [The Triassic dinosaur locality of Maphutseng (Basutoland) and the origin of sauropods]. Comptes Rendus de l'Académie des Sciences à Paris, Série D. 262, 444-447.
Ellenberger, 1970. Les niveaux paléontologiques de première apparition des mammifères primoridaux en Afrique du Sud et leur ichnologie. Establissement de zones stratigraphiques detaillees dans le Stormberg du Lesotho (Afrique du Sud) (Trias Supérieur à Jurassique) [The paleontological levels of the first appearance of primordial mammals in southern Africa and their ichnology. Establishment of detailed stratigraphic zones in the Stormberg of Lesotho (southern Africa) (Upper Triassic to Jurassic). in Haughton (ed.). Second Symposium on Gondwana Stratigraphy and Paleontology, International Union of Geological Sciences. Council for Scientific and Industrial Research, Pretoria. 343-370.
Ellenberger, 1972. Contribution à la classification des Pistes de Vertébrés du Trias: Les types du Stormberg d'Afrique du Sud (I). Palaeovertebrata. 104, 152 pp.
Kitching and Raath, 1984. Fossils from the Elliot and Clarens Formations (Karoo Sequence) of the Northeastern Cape, Orange Free State and Lesotho, and a suggested biozonation based on tetrapods. Palaeontologia Africana. 25, 111-125.
Chure and McIntosh, 1989. A Bibliography of the Dinosauria (Exclusive of the Aves) 1677-1986. Museum of Western Colorado Paleontology Series #1. 226 pp.
Olshevsky, 1991. A Revision of the Parainfraclass Archosauria Cope, 1869, Excluding the Advanced Crocodylia. Mesozoic Meanderings. 2, 196 pp.
Glut, 1997. Dinosaurs - The Encyclopedia. McFarland Press, Jefferson, NC. 1076 pp.
Knoll, 2004. Review of the tetrapod fauna of the "Lower Stormberg Group" of the main Karoo Basin (southern Africa): Implication for the age of the Lower Elliot Formation. Bulletin de la Societe Geologique de France. 175(1), 73-83.
"Likhoelesaurus" Ellenberger, 1970
"L. ingens" Ellenberger, 1970
= "Likhoelesaurus ferox" Ellenberger, 1972
Norian, Late Triassic
Lower Elliot Formation, Lesotho
Material- five teeth (70 mm)
Comments- Ellenberger and Ginsberg (1966) mentioned carnivorous dinosaur teeth from the Lower Elliot Formation, which were later called "Likhoelesaurus ingens" by Ellenberger (1970) and referred to Ornithosuchidae. These were not described properly though, making the name a nomen nudum. Ellenberger (1972) referred to "Likhoelesaurus ferox" as a "giant carnosaur" from zone A/5 of his lower red beds, illustrating five associated recurved teeth in a plate. This was another nomen nudum, with no explanation of the different species name (it may involve Basutodon ferox, but even if "Likhoelesaurus" were officially named, Basutodon would have priority). Kitching and Raath (1984) suggested it may be a junior synonym of Basutodon ferox. It was listed as a teratosaurid theropod by Chure and McIntosh (1989) and a melanorosaurid by Olshevsky (1991). Glut (1997) listed it as ?Theropoda incertae sedis, listed "?bones" among the remains and stated the teeth were 70 mm long. Knoll (2004) discusses the material under Rauisuchia, but notes it could be theropod as well.
 |
| Presumably the type material of "Likhoelesaurus ingens", from Ellenberger (1972). |
With no published description, and only one undetailed photograph, the phylogenetic position of "Likhoelesaurus" remains uncertain. While their recurved morphology excludes referral to Melanorosauridae or any other sauropodomorph clade, differences between the teeth of carnivorous dinosaurs, crutotarsans (including ornithosuchids and teratosaurs) and other carnivorous archosauriforms have yet to be studied. Indeed, they are only assumed to be archosauriform here due to past identifications, since the presence of serrations has not been confirmed. Synonymy with Basutodon is possible, but no shared derived characters have been suggested, Basutodon itself is probably undiagnostic and multiple archosauriform taxa are known from other Late Triassic localities.
References- Ellenberger and Ginsberg, 1966. Le gisement de Dinosauriens triasiques de Maphutseng (Basutoland) et l'origine des Sauropodes [The Triassic dinosaur locality of Maphutseng (Basutoland) and the origin of sauropods]. Comptes Rendus de l'Académie des Sciences à Paris, Série D. 262, 444-447.
Ellenberger, 1970. Les niveaux paléontologiques de première apparition des mammifères primoridaux en Afrique du Sud et leur ichnologie. Establissement de zones stratigraphiques detaillees dans le Stormberg du Lesotho (Afrique du Sud) (Trias Supérieur à Jurassique) [The paleontological levels of the first appearance of primordial mammals in southern Africa and their ichnology. Establishment of detailed stratigraphic zones in the Stormberg of Lesotho (southern Africa) (Upper Triassic to Jurassic). in Haughton (ed.). Second Symposium on Gondwana Stratigraphy and Paleontology, International Union of Geological Sciences. Council for Scientific and Industrial Research, Pretoria. 343-370.
Ellenberger, 1972. Contribution à la classification des Pistes de Vertébrés du Trias: Les types du Stormberg d'Afrique du Sud (I). Palaeovertebrata. 104, 152 pp.
Kitching and Raath, 1984. Fossils from the Elliot and Clarens Formations (Karoo Sequence) of the Northeastern Cape, Orange Free State and Lesotho, and a suggested biozonation based on tetrapods. Palaeontologia Africana. 25, 111-125.
Chure and McIntosh, 1989. A Bibliography of the Dinosauria (Exclusive of the Aves) 1677-1986. Museum of Western Colorado Paleontology Series #1. 226 pp.
Olshevsky, 1991. A Revision of the Parainfraclass Archosauria Cope, 1869, Excluding the Advanced Crocodylia. Mesozoic Meanderings. 2, 196 pp.
Glut, 1997. Dinosaurs - The Encyclopedia. McFarland Press, Jefferson, NC. 1076 pp.
Knoll, 2004. Review of the tetrapod fauna of the "Lower Stormberg Group" of the main Karoo Basin (southern Africa): Implication for the age of the Lower Elliot Formation. Bulletin de la Societe Geologique de France. 175(1), 73-83.
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