Theropoda: Avetheropoda

Carnosauria was originally used as a general term for all of the big theropods, including the elusive and quite possibly non-existent, Megalosaurus, the Snark of dinosaurs. In the 1920's Huene suggested that, despite its position as the biggest and baddest theropod, Tyrannosaurus looked a lot more as if it belonged with the "small" theropods, the Coelurosauria. However, this was the Jurassic of paleontology, and most dinosaur paleontologists were lumbering, slow-moving, low-metabolism forms. With the advent of cladistic adaptations in the 1980's, dinosaur paleontologists became faster, hungrier and more predatory. The more derived forms began dismembering virtually defenseless nineteenth century taxa with lightning-fast computers, developing, in the process, enlarged manual phalanges from entering data. Others began hunting in packs, with alpha professors leading viscious gangs of slavering, pencil-wielding graduate students through the Mesozoic halls of their museums in search of prey.

Just in this manner was Carnosauria decimated. At first, only the oldest and weakest members, like Megalosaurus, were picked off. But the blood lust of the new paleontology knew no bounds. In just a few short years, all that was left of Carnosauria were Allosaurus and a few meager, nondescript bones at the bottom of the largest and rustiest drawers of the most obscure museums.

Recently, however, intensive conservation efforts by Tom Holtz and others have resulted in a remarkable worldwide resurgence. With the discovery of Giganotosaurus and related forms, Carnosauria is once again the home of the world's largest terrestrial predators. Cryolophosaurus and other, as yet undescribed, species from Gondwanaland could lead to a renaissance of the Carnosauria. Even so, the threat of extinction remains very real. Paul Sereno, backed by the awesome commercial might of the National Geographic Society, has sworn to exterminate the Carnosauria and crush its quivering remains into Allosauroidea, leaving nothing but coelurosaurs and a random miscellany of basal "neotetanurines" (i.e. avetheropods).

Citizens! This is the taxon that made Victorian Englishmen gasp in horror at the Crystal Gardens in 1854. This is the clade that made movie critics shudder at "Carnosaur." This is the group that even made paleontologists scream at the publication in a kids' book of "Elvisaurus." Save the Carnosaurs!

Sinraptoridae

Something about carnosaurs seems to draw the best from people. Some of the most extraordinary monographs in paleontology were inspired by the giant Jurassic killers, and Currie & Zhao (1993) is one of them. It is well-written, copiously illustrated, reflects careful comparison with related forms, and contains some useful reflections on the functional significance of some of the more important morphological findings. It is everything a monograph should be.

It is important to be clear on the many strong points of this article, because I am going to take issue with its one weak point. Many readers will of the article will not have the several hours it takes to work through the entire piece. In fact, perhaps the majority will only read the family and species diagnosis at the beginning, and one or two anatomical points of special interest to them.

The problem is that there appear to be some significant errors or ambiguities in the family diagnosis. These are contained in a long list of characters which unite sinraptorids with allosaurids as follows:

(a) "upper qudratojugal prong of jugal shorter than jugal prong." Sinraptor has three prongs on the quadratojugal process of the jugal. the external (i.e. lateral) prongs are roughly the same size. It is the medial prong that is long. Dorsoventrally, this is neither the upper or lower prong, but falls between the lateral prongs. The medial prong is likely homologous to the lower prong of two in, e.g., Allosaurus, but the description as given is either confusing or erroneous.

(b) "braincase box has opened up posteriorly between tubera, which are no longer pedunculate." The actual conformation of the occiput is shown in Currie & Zhao's Figure 7A, which is reproduced at right. The braincase box, as I understand the term (which is not used elsewhere in the text), does not open up posteriorly, and there is nothing between the basal tubera which are, in fact, at least slightly pedunculate. Perhaps the authors are referring to some other tubera. Perhaps "posterior" was not the correct indication. Perhaps I have misunderstood the text. However, at a minimum, the diagnosis is unclear.

(c) "oval muscular attachment on basioccipital." Nothing at all is said about this in the text.

(d) "posteroventral limit of the exoccipital-opisthotic contacts the basisphenoid but is separated from the basal tubera by a notch." This may be correct, but it is not clear from the actual description, which reads: "Sinraptor is unusual in that the exoccipitals extend significantly more ventrally than the basal tubera. In most theropods, including ... allosaurids ... the ventral limit of the exoccipital-opisthotic along the basioccipital and basisphenoid suture is either at the same level or is dorsal to the level of the basal tubera. A notch separates the basal tuber from the more anteroventral extension of the exoccipital-basisphenoid suture as in allosaurids." (Id. at 2049, citations omitted). So, the notch is common to sinraptorids and allosaurids. However, the entire morphology of the occiput here is quite distinct. The similarity exists but is not likely to be an indication of common ancestry.

(e) "Tenth presacral vertebra in process of incorporation into dorsal, rather than cervical region." What could "in process of incorporation" mean? What the text actually indicates is that the 10th presacral vertebra is a cervical vertebra, although it bears some similarities with the tenth presacral in Allosaurus, which is a dorsal vertebra. (Id. at 2057 & 2065).

(f) "triangular neurapophysis." What is meant here is apparently "triangular neurapophysis on the axis-atlas complex." (see id. at 2055).

The really interesting and peculiar thing about sinraptorids may be the way in which the head was held. As Currie & Zhong note: "The shapes and alignment of the axial intercentrum and centrum served to bring the neck underneath the occipital condyle to support the skull in a manner that is unique amongst Jurassic theropods, with only Monolophosaurus, Y[angchuanensis] magnus and an undescribed theropod showing a tendency towards doing the same thing." (Id. at 2057, citations omitted.)

This posture is reflected in life restorations of Sinraptor and Allosaurus by Shiraishi Mineo. The head of Sinraptor is held higher. The anterior part of the back is arched to compensate (as also noted by Currie & Zhao). The difference in carriage may well be responsible for a number of differences between Allosaurus and Sinraptor, such as the anteroventral extension of the opisthotic-exoccipital, the use of the 10th presacral vertebra as a cervical, rotation of the atlas intercentrum, and apparently greater emphasis on stiffening the back with hyposphene-hypantrum articulations.

To speculate further on function, one might envision Sinraptor as a slower, but more maneuverable, version of Allosaurus. Sinraptor was more anteroposteriorly compact and laterally rigid. It might well have been able to shift its weight rapidly from side to side, as suggested by Currie & Zhao's notes on locomotion discussed in the main entry. The raised position of the head combined with rapid shifts in its center of gravity would also allow Sinraptor to attack over a wider angle compared to the antero-posterior axis of its body when the attack began. Running in this position would be awkward, but Sinraptor would have the advantage in an ambush attack. Perhaps this is also the reason for the fact that Sinraptor has an even more completely pneumatized skull than Allosaurus. Allosaurus would rely on the lightness and speed of its entire body. Sinraptor would rely more on the speed of its head. This is, perhaps, a parallel development to the changes in posture which led to the upright carriage of birds.

Avetheropoda: (= Neotetanurae = Allosauria = Allosauroidea of some authors) Birds + Allosaurus (Padian et al. (1999)) 

Range: Early Jurassic-Late Cretaceous. 

Phylogeny: Tetanurae : Torvosauroidea + *: Carnosauria + Coelurosauria.

Characters: U-shaped premaxillary symphysis; tapering posterior of coracoid; proximal half of metacarpal I closely appressed to metacarpal II; pubic boot; loss of obturator foramen; cnemial process originates on lateral surface (of tibia).

EHP Crosslinks:  DD: Avetheropoda 

Carnosauria (= Allosauroidea sensu Sereno (1999)) Allosaurus > birds (Padian et al. (1999)).

With the exclusion of Tyrannosauroidea (now considered a giant Coelurosaur lineage), only the Allosaurids and their relatives make up the Carnosauria. The name "Allosauria" was coined by Greg Paul in his superb book Predatory Dinosaurs of the World and seems to have caught on, although "Carnosauria" is still sometimes used. I prefer it for its historical connotations. See below. In any case, these were big to enormous bipedal terrestrial preditors, that for some one hundred million years or so were the dominant form of life on land.

Range:  Early Jurassic to Late Cretaceous. 

Phylogeny: Avetheropoda : Coelurosauria + *: Cryolophosaurus + ( Monolophosaurus + Allosauroidea). 

Characters: Large, long, narrow skull; $ enlarged nares; $ nasal participates in antorbital fossa; pre-orbital horns, commonly based in lacrimal; antorbital fenestra is expanded upwards; $ large cavity in lacrimal at antero-dorsal margin of orbit (possible gland of unknown function); skull commonly crested; large orbits; cheek flat, vertical, at sharp angle to skull roof [CC00]; quadrate with broad quadratojugal flange; quadrate short, with head at mid-orbit level; basioccipital excluded from basal tubera (but Sinraptor?); $ basipterygoid process very short; basi- parasphenoid formed by delicate-looking thin webs of bone; opisthocoelous vertebrae; pubic boot longer anteriorly than posteriorly; pubic boot triangular with apex posterior in ventral view; femur larger than tibia. 

Links: DinoData: Carnosauria; The Brutal Carnosaurs; carnosauria; VPTHEROPOD; Lecture 14 - Late Jurassic: Morrison, Tendaguru; MEA592D Dinosaur Osteology: Lecture 4; Carnosauria -- The Dinosauricon; Carnosauria; Carnosauria (Spanish); Carnosaurs: ZoomDinosaurs.com; What groups of dinosaurs existed?; Allosauria (Dutch); theropods; CARNOSAURIA (Spanish); CARNOSAURS; Untitled Document (Japanese); Geology poster; Carnosauria; ???????(Carnosauria) (Korean); Geology poster.   

References: Currie & Carpenter (2000) [CC00]; Currie & Zhao (1993); Sereno (1997). ATW021222.

Cryolophosaurus (informal senior synonym: Elvisaurus) 

Introduction: As the name implies, Cryolophosaurus is a crested theropod from a cold land.  This in fact is misleading, because during the early Jurassic Antarctica was part of the vast and warm (if not tropical, then certainly very temperate) landmass of Gondwana. This animal was found in association with prosauropods. It is probably too primitive to go under the Sinraptoridae proper, but could perhaps be considered a proto-sinraptorid. This advanced (for its time) animal was a contemporary of the big Dilophosaurs, but is more heavily built and provably had different feeding strategies. (MAK) 

Range: Early Jurassic of Antarctica. 

Phylogeny: Carnosauria : (Monolophosaurus + Allosauroidea) + *. 

Characters: Large (7-8) carnosaur. Skull 65 cm long; skull tall & narrow; large antorbital fenestra; nasals form ridges which merge with supraorbital crest; crest extends whole distance between orbits; crest mainly composed of lacrimal; 2 small lacrimal horns posterolateral to crest; lacrimal pneumatized; lateral temporal fenestra divided by processes of postorbital and squamosal; quadrate short; hindlimbs primitive. 

Links: DD: Cryolophosaurus; Cryolophosaurus -- The Dinosauricon; Cryolophosaurus; Dino Land Cryolophosaurus tooth; Cryolophosaurus by Keith Strasser; Cryolophosaurus (Dutch); Polar dinosaurs in Australia; Augustana Geology Department In Antarctica. 

References: Rich et al. (1997). 

Note: Recovered from Mt. Kirkpatrick, a site at a paleolatitude of 61-70° S (presently 84° S). Crest, unlike most Allosauroid crests, seems to have been structured for anteroposterior, not lateral, display. Cryolophosaurus is the oldest known Tetanuran. 010511.

Monolophosaurus:

Introduction: This animal is characterised by what seems to be a single ridge-like head crest running from its nose to the rear of the skull. This feature is not found in any other theropod, so either this is a very distinctive form or it is simply an artifact of preservation. (MAK)

Range: Middle Jurassic of China. 

Phylogeny: Carnosauria :: Allosauroidea + *. 

Characters: Dorsal surface of nasal convex and rugose; facial horns present [CC00]; dorsal surface of frontals convex [CC00]; some caudal vertebrae with hyposphenes; supraacetabular shelf continuous with lateral margin of pubic peduncle. 

References: Currie & Carpenter (2000) [CC00]; Currie & Zhao (1993). ATW060206.

Allosauroidea: Lourinhanosaurus. Allosaurus + Sinraptor. Padian et al. (1999). 

Introduction: Allosauroidea is considered a monophyletic clade divided into three similiarily mmonophyletic families: the Sinraptoridae, the Allosauridae, and the Carcharodontosauridae. Greg Paul considers the small late Jurassic Ornitholestes and the earlier and larger Proceratosaurus to be also Allosaurs. Other dinosaurologists tend to classify Ornitholestes as a basal (i.e. primitive/ancestral) coelurosaur. An animal much like Ornitholestes, and living same ten or twenty million years earlier, might have been the common ancestor of both. (adopted from MAK)

Range: Early Jurassic-Late Cretaceous. 

Phylogeny: Carnosauria :: Monolophosaurus + *: Sinraptoridae +  Allosauridae. 

Characters: Usually 7-10m long, laterally compressed. Long, narrow skull; flange-shaped lacrimal process on palatine; $ articular with pendant(?) medial process; $ participation of nasal in antorbital fossa; antorbital fenestra expanded dorsally; maxillary fenestra expanded dorsally to form hole in lacrimal (probably plesiomorphic for carnosaurs); pneumatic excavation of ascending ramus of maxilla (same character, described differently); lacrimal recess, single opening present (another aspect of the same character state); narial prominences comprised of paired ridges along lateral edges of nasals; postorbital prominences present; orbits large; lacrimal horns and crests common; quadrate articultion projects well ventral of ventral surface of maxilla; horizontal shelf on lateral surface of surangular, rostroventral to mandibule condyle, prominent and pendant; caudal dorsal neural spines oriented cranially; three fingers per hand; manus digits 2 & 3 roughly equal with 2 slightly longer; pubic boot triangular (apex caudal) in ventral view, acute angle between shaft and caudal portion of boot; $ femur usually larger than tibia; 2 distal tarsals (III & IV). 

Links: DD: Allosauroidea; theropods; carnosauria; Dann's Dinosaur Info: Allosauroid; MEA592D Dinosaur Osteology: Lecture 4; Allosauridae & Sinraptoridae.(Best on the Web); Currie & Carpenter (full text article); PhyloCode Discussion - Message 2003-07-0007- Allosaurus whitei ...; Redescription de Streptospondylus altdorfensis , le dinosaure ...; Click Here!.   

References: Currie & Zhao (1993). ATW031029.

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