Details on SVP 2001 Friday talks

Sorry about how late this is. College has kept me busy, plus MSN refused to let me post to the list from the fifteenth until yesterday.

Friday had some of the best talks, but non-dinosaurian posters.

Heckert and Lucas, 2001. What are the oldest dinosaurs? JVP 21(3) 60A.

I missed most of this talk (slept in...), but basically it states the oldest dinosaurs are Otischalkian (Middle Carnian). Even the new Malagasy basal sauropodomorphs are said to be this age, apparently co-existing with Carnian index fossils like Stagonolepis and Hyperodapedon.

Pisani, Yates and Langer, 2001. The first supertree for the Dinosauria. JVP 21(3) 89A.

Oh, how I hate supertrees. A supertree is a cladogram made by combining other cladograms together to form a "consensus cladogram" of what arrangements are favored by most of them. So if three cladograms support tyrannosauroids as arctometatarsalians and one supports them as maniraptorans, they will come out as arctometatarsalians. This ignores the fact that different phylogenetic analyses almost always use many of the same characters, so I'm sure certain characters were present in at least 20 of the 127 cladograms combined in this study. Thus, the historically oldest found characters are favored over new characters by unintentional weighting. Basically, supertrees are an average of the ideas people have had in the past decade for phylogenetic relationships, nothing more. On a more positive note, Adam Yates did a great job in his presentation considering he had to prepare it the night before due to unforeseen circumstances.

Langer, 2001. Early dinosaur phylogeny: Are any of the hypotheses better supported? JVP 21(3) 71A.

Langer performed a phylogenetic analysis of nine taxa and 119 characters with the following topology-

|-+-Pisanosaurus
| `-other Ornithischia
`-+-+-Staurikosaurus
| `-Herrerasaurus
`-+-Eoraptor
    `-+-+-Saturnalia
      | `-other Sauropodomorpha
      `-+-Guaibasaurus
        `-other Theropoda

14 more steps are needed to place herrerasaurids outside of Dinosauria (Saurischia having a 97% bootstrap). Saurischia is supported by- humerofemoral ratio >60%; manus >40% of humeroradial length; metacarpal IV very narrow; curved manual unguals; manual unguals with deep, asymmetrical flexor pits. Eoraptor was sister to eusaurischians based on- thin posterior premaxillary process; maxilla with concave anterior margin; lateral maxillary ridge; nasal contacts antorbital fenestra; long, subvertical ventral lacrimal process. Sauropodomorpha (bootstrap 80%) was supported by such characters as- wide distal humerus; short caudal premaxillary process; posterior cervicals longer than dorsals. Finally, Saturnalia was more basal than other sauropodomorphs based on- straight rostral dentary; no pubic apron; proximally placed fourth trochantor; fibula articulates distally with astragalus; metatarsal IV not proximally flared. These character lists are not complete- I didn't have nearly enough time to copy them all.

Yates, 2001. A new look at Thecodontosaurus and the origin of sauropod dinosaurs. JVP 21(3) 116A.

A new species of Thecodontosaurus from the Triassic of Wales is described. It is assigned to Thecodontosaurus based on the presence of overhanging planar cervical postzygopophyses. It lacks autapomorphies of T. antiquus, like a short dorsoventrally deep preacetabular process. It also has at least one unique character- possibly pneumatic fossae on the neurocentral suture of cervicals 6-8. A phylogenetic analysis of 19 taxa and 164 characters resulted in the following topology-

|-Saturnalia
`-+-+-Thecodontosaurus antiquus
| `-Thecodontosaurus sp. nov.
`-+-"Efraasia"
    `-+-Plateosaurus
      `-+-+-Lufengosaurus
        | `-Massospondylus
        `-+-Melanorosaurus
          `-+-Blikanosaurus
            `-Sauropoda

Galton, 2001. Valid species of prosauropod dinosaurs from the Upper Triassic of Germany. JVP 21(3) 52A.

Galton thinks Sellosaurus is more than one species- Efraasia diagnostica and Sellosaurus gracilis. Plateosaurus engelhardti (the holotype) is diagnosed by- sacral rib 1 originates from complete length of sacral centrum 1; sacral rib 2 originates from posterior 75% of sacral rib 2. Plateosaurus longiceps (= P. trossingensis) is valid, but P. erlenbergiensis is generically indeterminate. Most specimens (from Halberstadt, Trossingen, Stuttgart-Degerloch, France, Switzerland and Greenland) are of P. longiceps, but Bavarian ones are P. engelhardti. A cladogram was shown-

|-Thecodontosaurus
`-+-Saturnalia
`-+-+-+-Anchisaurus
    | | `-Ammosaurus
    | `-+-Riojasaurus
    |   `-+-Camelotia
    |     `-Melanorosaurus
    `-+-Jingshanosaurus
      `-+-Massospondylus
        `-+-+-Yunnanosaurus
          | `-Euskelosaurus
          `-+-Sellosaurus
            `-+-Coloradisaurus
              `-+-Plateosaurus
                `-+-"Gyposaurus" sinensis
                  `-Lufengosaurus

Hwang, Norell, Gao and Qiang, 2001. New information on Jehol theropods. JVP 21(3) 64A.

Two new specimens of Microraptor were shown- CAGS 20-8-001 and CAGS 20-7-004. They are similar in size, having trunk lengths of 90 mm and 100 mm respectively. The former is rather poorly preserved, but does have complete manus and partial skull, while the latter is complete except for the skull and cervicals. Lots of new morphological information was revealed. Posterior dorsals have stalked parapophyses. Pleurocoels are absent from all dorsals and the dorsal neural spines are 1.1 times centrum length. Uncinate processes have expanded distal ends and span 3 ribs. Five sacrals are present, whose neural spines are fused into a lamina and transverse processes fused to the ilia. The scapulocoracoid was "L-shaped", though I don't know if this indicates an acute or obtuse angle. Like many maniraptoriformes these days, the glenoid faces laterally. The sternum has lateral processes and costal facets for four sternal ribs. The furcula has an interclavicular angle of 92 degrees in one specimen, but 81 degrees in the other. Additionally, one furcula has a rounded ventral edge like Sinornithosaurus, while the other is more angular like Velociraptor. No other differences between the specimens were noted and both share Microraptor autapomorphies (accessory trochantor; middle caudal centra three times longer than anterior dorsal centra). There is a large internal tuberosity on the humerus and a well developed olecranon on the ulna. Oddly, all metacarpals are subequal in length, with digit I having an especially large ungual. The pubic peduncle's distal edge is posteroventrally oriented.

The specimen that was to be named "Huaxiasaurus" (NGMC 98-5-003) from the Lower Yixian Formation at Sihuten, Liaoning Province. The specimen looks fairly complete, but its various pieces were placed together inaccurately by those who found it. Thus, it's hard to interpret correctly, with the tibiae placed incorrectly in pieces and the tail with an unknown amount of missing vertebrae. As reconstructed, it's 1.79 meters long. The abstract says it has a metatarsofemoral ratio of 30% and a radiohumeral ratio of 50%. The manus has long phalanges with large claws and the tibia is 150% longer than the femur. They didn't describe it at all in the talk, so perhaps these ratios are based on the inaccurately reconstructed element lengths, and the specimen was only realized to be so poorly reconstructed after the abstract was submitted. I don't know.

A phylogenetic analysis with 205 characters and 48 taxa was shown, using genera or species as OTU's. Because of this, it was impossible to copy down completely, but the higher relationships were-

Note how low alvarezsaurids are, very Sereno-esque. Enigmosaurs are monophyletic, despite what Clark et al. (2001) said about Norell, Clark and Makovicky in press. Troodontids are not only deinonychosaurs, but are paraphyletic to dromaeosaurids in at least some trees. Only a reduced Troodontidae of Saurornithoides+Troodon was found consistantly. The new troodontid taxon was named in the slide, but unlike Psittacosaurus sibiricus, not in the abstract. Thus, I cannot reveal its name in good conscience. I will say however, that those of you annoyed with Sinosaurus, Sinosauropteryx, Sinornithosaurus, Sinornithoides, Sinornis, Sinocoelurus and Sinraptor will not be pleased.

Gatesy, 2001. In search of the flight stroke: The evolution of theropod forelimb motion. JVP 21(3) 53A.

Foster, Holtz and Chure, 2001. Contrasting patterns of diversity and community structure in the theropod faunas of the Late Jurassic and Late Cretaceous of Western North America. JVP 21(3) 51A.

The main point of this talk was that the Morrison Formation has a wide size range of theropods, with several taxa in the largest size range (500+ kg), while the Hell Creek has fewer theropod taxa, only one of which is over 500 kg. Oddly, Ceratosaurus was said to be much smaller than Allosaurus, presumedly based on the subadult holotype.

"What about Albertosaurus?!" :-)

Britt, Chure, Stadtman, Madsen, Scheetz and Burge, 2001. New osteological data and the affinities of Utahraptor from the Cedar Mountain Fm. (Early Cretaceous) of Utah. JVP 21(3) 36A.

New elements from the Dalton Wells Quarry and Yellow Cat Quarry are described- 190 elements of over seven individuals. The lacrimal of the original description is actually a postorbital from Gastonia. Also, the manual unguals of the original description are actually pedal unguals. More premaxillae have been found, as has a nasal. The quadratojugal is not even slightly T-shaped. Cervicals are very short with strongly angled centra and pleurocoels. Anterior dorsals have two pairs of pleurocoels, like Achillobator, and large hypapophyses. The presacrals are camellate, but the posterior dorsal centra lack pleurocoels. Sacrals are known and proximal caudal centra are quadrangular in section. A coracoid has been found, which is shorter than Deinonychus' with a longer posteroventral process like Achillobator. There is an ilial fragment, including the pubic peduncle and a small part of the preacetabular process. The pubic peduncle faces ventrally and the preacetabular process has a ventrally expanded component. There is a broad m. cuppedicus shelf. The ischium has a proximally positioned triangular obturator process and a very small proximodorsal process. Femora have elevated heads and separate anterior trochantors. The ascending process is low but broad, being a bit taller than the astragalus is transversely wide. The metatarsus is not arctometatarsalian. A juvenile femur is 310 mm, but an adult is 565 mm long. There are also caudal vertebrae more than twice the length of caudals belonging to the 565 mm femur specimen. For comparison, Achillobator has a femur 505 mm long. The specimen with the largest preserved femur was probably about 5.5 meters long, but the caudal could have come from a ten meter long specimen. The new data available suggests Utahraptor is closest to Achillobator.

Kellner, 2001. New information on the theropod dinosaurs from the Santana Formation (Aptian-Albian), Araripe Basin, Northeastern Brazil. JVP 21(3) 67A.

A bit more was revealed about Santanaraptor, which is getting a full description soon. The caudal vertebrae have anterior spurs like several more basal tetanurines. The femur has no anterior extensor groove distally and the ascending process is very high with a strong groove at its base. Kellner continues to diagnose it in part on the "large obturator notch", but this is merely a derived coelurosaur character. He now places it in the Tyrannoraptora based on Sereno's 2000 analysis which defined the clade based in part on the absent ischial foot, but this is also found in the more basal coelurosaur Ornitholestes.

A spinosaurid specimen from the Santana Formation (MN 4802-V) presumedly comes from Irritator and consists of a sacrum, caudal vertebrae, incomplete forelimbs, a pelvis and incomplete hindlimbs. There is a large first manual ungual, the ilium is 553 mm long and there is an ischial obturator notch.

Varricchio, 2001. "Beautiful wounding tooth": Ontogeny and osteology in the theropod Troodon formosus. JVP 21(3) 110A.

Lots of new Troodon material from the Two Medicine Formation. There are two pairs of cervical pleurocoels (like "utahraptorines" and enigmosaurs). The scapula has an anteriorly projecting acromion and laterally facing glenoid (the latter seemingly not present in Sinornithoides). There are both gracile and robust humeri, but the former seem to be immature animals that will grow to be larger than others. Distally, the humeral condyles face anteriorly in Troodon, but not Sinornithoides. The postacetabular process in juveniles is tapered and the pubis may be retroverted, though the proximal articulation is hidden. Adults have approximately vertical pubes with a larger anterior foot and straight shaft. The ischium has an obturator process placed at midlength and no proximodorsal process. An "obturator tuberosity" is reported to be present on the ischium, but I don't know what it could be. The fibula does not contact the calcaneum. Embryonic specimens show distal limb elements decrease in length compared to the femur with growth, but humerofemoral ratios stay constant. An adult (MOR 748) had the following dimensions- femur 320 mm, tibia 362 mm, metatarsus 227 mm.

Norell, Makovicky, Currie and Ji, 2001. Three cases of soft-tissue preservation in theropod dinosaurs: Changing our perception of theropod appearence. JVP 21(3) 83A-84A.

The distribution of different types of integument on cf. Sinornithosaurus is explained in detail- single filaments are on the head and tail, sprays of multiple filaments from a single base are on the body and thigh while true feathers are on the arms. Another Sinornithosaurus specimen (BI 3-13) is also described. It is almost complete, preserved in side view. There are long feathers with rachis on the forelimbs and hindlimbs, as well as a 250 millimeter long tail frond.

Holtz, 2001. Pedigree of the tyrant kings: New information on the origin and evolution of the Tyrannosauridae. JVP 21(3) 62A-63A.

Holtz had a phylogeny of theropods with 85 taxa and 642 characters with the following topology-

Notice the paraphyletic Ceratosauria sensu lato, basal position of "Szechuanosaurus" zigongensis like Rauhut 2000, odd Siamotyrannus+Fukuiraptor clade, Dryptosaurus in the Tyrannosauroidea and Coelurus being more derived than other "basal coelurosaurs". Also, Avimimus is an oviraptorosaur, Protarchaeopteryx a paravian and there is no evidence for secondary flightlessness. What an interesting cladogram, I wish I could have copied the rest of the taxa.

Longrich, 2001. Secondarily flightless maniraptoran theropods? JVP 21(3) 74A.

Argued that several characters- remiges; retrices on a proximally flexible yet distally stiff tail; V-shaped tail in Caudipteryx; overlapping feathers with curved rachis; foldable forelimbs; anterior center of gravity; enlaged posteroventral pectoralis origin; thoracic bracing. His phylogeny based on 30 taxa and over 250 characters is-

No monophyletic Carnosauria, but perhaps this is because it centered on coelurosaur characters. Tyrannosauroids yet again very low, and alvarezsaurids are also low like the AMNH phylogeny. I like Bagaraatan as a basal maniraptoran and Protarchaeopteryx as an enigmosaur, while Avimimus seems to be finding a consensus as an oviraptorosaur in recent phylogenies. The paravian section looks implausible to me, mainly due to troodontids being deinonychosaurs. Secondary flightlessness of paravians is supported.

Mickey Mortimer