The theropods are somewhat bland on the surface, because they
all followed a body plan devoted to bipedal hunting on the ground, but they had a healthy variety of styles and variations on
their main theme. It is fairly well settled that birds are closely related to
theropods, although the placement and groups closest are not clear. I used
a theory that claims flight was achieved by animals just before the first true dromaeosaurids, making a number of classic (historically
considered non-avian and not having ancestors that could fly) theropods secondarily
flightless, meaning they had ancestors that could fly, but they themselves had lost that
ability. This is between two other theories, known colloquially as BADD (Birds Are Dinosaur
Descendants, with the emphasis here that no classic theropod was secondarily flightless)
and BCF (Birds Came First, with the premise that all classic theropods were secondarily
flightless). Since I've gotten my copy of The Dinosauria II, I've
finally come around to vanilla BADD.
The theropods were all bipedal, as far as is known, and the majority of the classic theropods were predators, with some exceptions: the oviraptorosaurians, troodontids, and ornithomimosauroids may have been herbivorous or omnivorous. They all likely could move reasonably fast; the large theropods had their speed helped by their long legs. By taking large strides quickly, they could move fast without running if they chose. It is likely that at least all theropods that were members of Coelurosauria either were covered with a downy "protofeather" coating or had lost that characteristic.
Some important anatomical characters linking all theropods ancestrally include an extra hole in the skull's maxilla, a reduction or loss of both the fourth and fifth digit of the hand, hollow long bones, reduction of the fifth digit of the foot to almost nothing, and presacrals bearing holes (pleurocoels) to hollow centra.
In the past, a group called the teratosaurids was considered to be the earliest "carnosaurs," and sometimes was aligned with the prosauropods. This group was eventually discovered to be based on "thecodont" remains, sometimes mixed with prosauropods remains for good measure, but not before working its way into the popular literature. A fair number of older (pre~1985) books on dinosaurs include (very hypothetical) restorations of "teratosaurids".
Although it was recently thought that a sauropod, Eobrontosaurus, had "belly ribs," it appears that only theropods and prosauropods had these, which would have protected the belly area. In addition, many theropods have been restored with their palms facing down or back, which would have been impossible due to lack of the proper forearm rotation for most (if not all) of them. Instead, theropod hands would have faced each other.
An interesting possibility suggests that the adults of small theropods may have had to compete with the juveniles of large theropods, particularly if the parents had left the young to fend for themselves at an early age. This in effect would have made these juveniles almost a separate species. Theropods may have also done communal nesting, as suggested by remains found in Portugal.
An unusual small tooth from the Late Campanian of Mexico has a peculiar groove that could indicate the existence of a small, venomous theropod.
|Taxon or Taxa:||Time/Place:||Comments:|
|Daemonosaurus chauliodus Sues, Nesbitt, Berman, and Henrici, 2011||late Rhaetian (LTr) of New Mexico||Daemonosaurus is the second genus of theropod from the Ghost Ranch site. It is known from a skull, cervicals, and ribs, and is notable for its short high skull featuring large anterior teeth, particularly in the premaxillae.|
|Tawa hallae Nesbitt, N. Smith, Irmis, Turner, Downs, and Norell, 2009||mid Norian (LTr) of New Mexico||Tawa is a basal theropod with an interesting combination of features that show up in several different groups of basal dinosaurs and their relatives. Just eyeballing it, and not even going into the anatomical details, it combines a coelophysoid-like skull, a herrerasaurid-like ilium, unusually long femora and short tibiae, long humeri... Given how wacky many Triassic animals have turned out to be (table for four ready for Revueltosaurus, Shuvosaurus, Eucoelophysis, and Protoavis, and that's just from North America off the top of my head), it's quite useful that Tawa is based on an associated skeleton, and is known from another associated skeleton as well.|
Theropoda i.s.: Don't weep for most of these folks. Aside from a couple of animals that appear to belong around this level, these creatures earned their status, being based on little material, often poor in quality. More than a few tooth taxa appear in this following table, providing mute testimony to the fact that dinosaurs named from isolated teeth more often than not quickly enter into a usually richly-deserved obscurity. Occasionally, one will rise from the depths like Troodon on the basis of uniqueness, but this is rare (in the old days of dinosaur paleo, a dubious tooth name like Trachodon could became host to a taxonomical monstrosity of names and material, very little of which could ever be shown to pertain to the host taxon).
|Taxon or Taxa:||Time/Place:||Comments:|
|"Allosaurus" sibiricus (N.D.) Riabinin, 1914||Berriasian-Hauterivian (EK) of Buryatia, Russia||This obscure species is based on a chunk of metatarsal, perhaps from a megaraptoran.|
|Chienkosaurus ceratosauroides (N.D.) Yang, 1942||?LJ of China||Based on four teeth, three of which turned out to be crocodilian, and the other of which is usually thrown in with Szechuanosaurus campi, Chienkosaurus is probably not assignable to it, simply because the tooth is pretty much the same as those from Yangchuanosaurus and Sinraptor, too. It was originally thought to be close to Ceratosaurus, hence the species name.|
|"Creosaurus" potens (N.D.) Lull, 1911||late Aptian-early Albian (EK) of Maryland||"Creosaurus" potens is based on an unusual caudal vert.|
|Dandakosaurus indicus (N.D.) Yadagiri, 1990||Pliensbachian-Toarcian (EJ) of Andhra Pradesh, India||So far, this is a very mysterious animal. Little has yet been reported. It may be a ceratosaurian or basal tetanuran.|
|"Elaphrosaurus" iguidiensis (N.D.) Lapparent, 1960||late Aptian-Albian? (EK) of Algeria (Adrar and Ouargla), Libya (Gharyan) (uncertain geologic formation), and Niger (Agadez)||This species cannot be assigned with certainty to Elaphrosaurus. I wouldn't be surprised if some of the material assigned here belongs to abelisauroids, spinosaurids, or carcharodontosaurids.|
|Embasaurus minax (N.D.) Riabinin, 1931||Berriasian-Hauterivian (EK) of Aktobe, Kazakhstan||Both a geographic curiosity and poorly known, the vertebrae this form is based on could belong to a basal tetanuran or a tyrannosauroid.|
|Fosterovenator churei Dalman, 2014||Kimmeridgian (LJ) of Wyoming||This is some kind of small theropod, based on a tibia described as ceratosaurian but more likely tetanuran, with a referred "fibula" that is potentially another tetanuran tibia.|
|"Futabasaurus" (N.N.) Lambert, 1990||Coniacian (LK) of Japan||Some kind of large theropod known only from a partial tibia, "Futabasaurus" is not to be confused with Futabasaurus, a properly described elasmosaurid plesiosaur. The nicknamed theropod "Futabasaurus" predates the plesiosaur name, but was never officially published and would need a different name (and given the scanty material, don't expect any action, at least for the foreseeable future).|
|Inosaurus tedreftensis (N.D.) Lapparent, 1960||Berriasian-Barremian (EK) of Agadez, Niger, additional material assigned from Albian-early Cenomanian (EK-LK) of Niger (Agadez) and Egypt (Giza)||There's no proof that the seemingly arbitrarily-assigned remains named Inosaurus actually belong together, and minimal justification for the assignment. It is based on twenty-five small but heavily built vertebrae and part of a tibia, recovered from three different localities. Most are from Berriasian-Barremian-age rocks in Niger, with some from Albian-early Cenomanian-age rocks in Niger, and some from early Cenomanian-age rocks in Egypt. Most of the description is based on the older bones from Niger.|
|"Kagasaurus" (N.N.) Hisa, 1989||Hauterivian (EK) of Japan||"Kagasaurus", based on a tooth, may be coelurosaurian.|
|"Katsuyamasaurus" (N.N.) Lambert, 1990||Barremian (EK) of Japan||The name is interesting. This animal, based on an ulna and a (iguanodontian) caudal, may be a Sinraptor-Allosaurus type theropod, possibly the same as Fukuiraptor.|
|"Liassaurus huenei" (N.N.) Welles, Powell, and Pickering vide Pickering, 1995 (?Sarcosaurus)||Sinemurian (EJ) of England||This theropod is based on a collection of hindlimb and pelvic elements. These bones are from the same time and place as Sarcosaurus, and very similar to boot, so may belong to it.|
|"Massospondylus" rawesi (N.D.) Lydekker, 1890||late Maastrichtian (LK) of Maharashtra, India||This is a tooth taxon that may represent an abelisaurid.|
|"Megalosaurus":||"M." chubutensis (N.D.) Corro, 1974||LK of Argentina||This is an indeterminate tooth species that can't be assigned to the European MJ Megalosaurus, or any other theropod for that matter. It may have been a large abelisaurid.|
|"M." cloacinus (N.D.) Quenstedt, 1858||Rhaetian-early Hettangian (LTr-EJ) of Germany||Early tooth species.|
|"M." dunkeri (N.D.) Dames, 1884||Berriasian (EK) of Germany||Much more famous as its alter-ego Altispinax, "M." dunkeri is a tooth species from Germany that cannot be shown to have any connection to the three tall vertebrae assigned to it by Huene that formed the basis of the name Altispinax and now are known as Becklespinax. It used to be illustrated as having a sort of hump near the shoulders. It may be related to Prodeinodon and/or a maniraptoran or tyrannosauroid.|
|"M." hungaricus (N.D.) Nopcsa, 1901||early-mid Maastrichtian (LK) of Romania||This is just another tooth species, possibly a dromaeosaurid or tyrannosauroid.|
|"M." inexpectatus (N.D.) Corro, 1966||Albian-Cenomanian (EK-LK) of Argentina||The teeth this species is based on could belong to a carcharodontosaurid.|
|"M." insignis (N.D.) Eudes-Deslongchamps and Lennier, 1870||early Kimmeridgian (LJ) of France||This species is based on teeth and postcrania (possibly sauropodan), and additional remains are referred to it (particularly from Portugal, but these may belong to a teleosaurian crocodylomorph), but on what basis I don't know.|
|"M." lonzeensis (N.D.) Dollo, 1903||Santonian (LK) of Belgium||This isolated pedal ungual is not referable to Megalosaurus. It may be coelurosaurian.|
|"M." pannoniensis (N.D.) Seeley, 1881||early Campanian (LK) of Austria||This is just another doubtful tooth species, probably tetanuran (maybe a dromaeosaurid or tyrannosauroid).|
|"M." pombali (N.D.) Lapparent and Zbyszewski, 1957||Oxfordian-Kimmeridgian (LJ) of Portugal||Another tooth taxon, with some referred vertebrae.|
|"M." terquemi (N.D.) Huene, 1926||Hettangian (EJ) of France||This is (surprise) another doubtful tooth species. This one may not be dinosaurian.|
|"M." woodwardi (N.D.) Lydekker, 1909||Sinemurian (EJ) of England||We (finally!) reach the last of this batch of dubious Megalosaurus species, ending with another species based on teeth. To given you an idea of how important and notable this species is, the type specimen was given a second name in 1926 by von Huene, unaware that it already had a name. The name he chose, M. lydekkeri, gives us the unusual situation of a species name honoring the man who had already named the material years before! To cap the situation, von Huene (1932) himself came to name a theropod Megalosaurus woodwardi, which fittingly enough was based on the same material as "Sarcosaurus" andrewsi, named earlier in the same paper.|
|"Merosaurus newmani" (N.N.) Welles, Powell, and Pickering vide Pickering, 1995||late Sinemurian (EJ) of England||"Merosaurus" is based on leg material that was once part of the type material of Scelidosaurus. It may be a basal tetanuran, but it hasn't plotted as one when analyzed phylogenetically. At this point, it should be considered an early theropod of uncertain affinities. It may represent a tetanuran.|
|"Mifunesaurus" (N.N.) Hisa, 1989||mid Cenomanian (LK) of Japan||This is another undescribed theropod, "based" on a tooth but with a handful of other bones "referred" to it.|
|"Morosaurus" marchei (N.D.) Sauvage, 1897-98||Aptian-Cenomanian (EK-LK) of Portugal||This is a dubious theropod based on a distal caudal.|
|"Ngexisaurus dapukaensis" (N.N.) Zhao, 1983||MJ of China||Very little, beyond the interesting name, is known of this dinosaur, which may be a coelurosaurian or, according to the faunal list in The Dinosauria II, a ceratosaurian.|
|?"Ornithocheirus" hilsensis (N.D.) Koken, 1885||EK of Germany||Based on a toe bone, this was originally described as a species of the pterosaur Ornithocheirus, but it's more likely to have been a theropod. Unfortunately, the bone is now lost.|
|Orthogoniosaurus matleyi (N.D.) Das Gupta, 1931||mid-late Maastrichtian (LK) of Madhya Pradesh, India||This theropod is based on an odd tooth.|
|Ostafrikasaurus crassiserratus Buffetaut, 2012||mid-late Tithonian (LJ) of Mtwara, Tanzania||Known from a single tooth, Ostafrikasaurus was described as the earliest known spinosaurid. However, the tooth could instead represent a premaxillary tooth of a ceratosaurid.|
|Phaedrolosaurus ilikensis (N.D.) Dong, 1973||?Valanginian-Albian (EK) of China||Little is known about this theropod, which some have speculated is close to the ancestry of Dromaeosauridae. It is based on a somewhat dromaeosaurid-like but rather uninformative tooth. Referred non-dromaeosaurid but maniraptoran hindlimb material has been shown to be diagnostic and has been renamed Xinjiangovenator.|
|Prodeinodon mongoliensis (N.D.) Osborn, 1924||Barremian-early Aptian (EK) of Mongolia||This tooth taxon is based on some choppers with a resemblance to those named Aublysodon, suggesting possibly a young tyrannosaurid. It may, though, be a carnosaurian or maniraptoran.|
|"Prodeinodon" kwangshiensis (N.D.) Hou, Yeh, and Zhao, 1975||Barremian-early Aptian (EK) of China||This is a tooth taxon that may be close to the similarly poorly-known Wakinosaurus.|
|Protoavis texensis Chatterjee, 1991||early Norian (LTr) of Texas||Protoavis is a...thing, perhaps even a
"fiendish thingie", in the words of George Harrison, and
well-known for its charming habit of presenting a different face to
everyone who looks at it. This dinosaur represents a great controversy. Some
have called it an early bird, while others have considered it a chimerical
muddle. Its remains have been accused of coming from a combination of coelophysoids,
herrerasaurids, early coelurosaurs, and pterosaurs and various other
nondinosaurians. However, it is now beginning
to look as though much of the material goes together (although some was
misidentified originally). My best guess is
that this animal will turn out to be closest to the coelophysoids.
New restorations show a long forelimb, but the shoulder, hindlimb, and pelvis seem poorly known. Although many bones are known, the skeleton is still fragmentary and open to interpretation. Apparently, part of the hindlimb is coelophysoid, but parts of the rest of it are not, and I'll hold off putting it in one place until a type is decided upon.
|"Saurocephalus" monasterii (N.D. or N.N.) Münster, 1846||Oxfordian (LJ) of Germany||Originally described under the fish genus Saurocephalus and sometimes seen as Megalosaurus monasterii, this is an obscure tooth taxon.|
|Siamosaurus suteethorni (N.D.) Buffetaut and Ingavat, 1986||LJ or EK of Thailand||This is a possible spinosaurid based on teeth, although even its dinosaurian status is questionable.|
|Sinocoelurus fragilis (N.D.) Yang, 1942||Tithonian (LJ) of China||This tooth species has unserrated teeth reminiscent of spinosaurids, so it may be a small or juvenile early member. It also may not be; for example, the teeth could be from a crocodylomorph. Let it be known that I am probably the one who started the poorly-founded spinosaurid rumor.|
|Szechuanosaurus campi (N.D.) Yang, 1942||Oxfordian (LJ) of China||Szechuanosaurus is a name you may run across that isn't very useful. It was originally based on some shed teeth. Later, a headless partial skeleton was found and referred to this taxon ("S." zigongensis). This decision was based on some other teeth which were referred to the second species. Unfortunately, there is no conclusive way to link the teeth and skeleton, theropod teeth being what they are.|
|Teinurosaurus sauvagei (N.D.) Nopcsa, 1928 (species after Huene, 1932 [originally Caudocoelus])||Kimmeridgian (LJ) of France||The caudal vert this species is based on has gone through a taxonomic mess. Nopcsa, by typographical error, almost named it Saurornithoides, which wouldn't have mattered as much if that name wasn't already in use. Understandably, he quickly printed a clarification, which von Huene missed on his way to naming it Caudocoelus in 1932. It's dubious by any name.|
|"Tomodon" horrificus (N.D.) Leidy, 1865 (?Dryptosaurus)||?Maastrichtian (LK) of New Jersey||This animal, better known as Diplotomodon (Tomodon, it turned out, was preoccupied), is possibly the same as Dryptosaurus.|
|"Tripriodon" caperatus (N.D.) Marsh, 1889||late Maastrichtian (LK) of Colorado||This is another dubious tooth taxon, usually stuck with Paronychodon.|
|"Tyrannosaurus lanpingensis" (N.N.) Yeh, 1975||Berriasian-Hauterivian (EK) of China||This is an indeterminate tooth species, far too old to be Tyrannosaurus.|
|Wakinosaurus satoi (N.D.) Okazaki, 1992||Berriasian-?Hauterivian (EK) of Japan||Described as a "megalosaurid," Wakinosaurus satoi is based on teeth.|
|Walgettosuchus woodwardi (N.D.) Huene, 1932||Albian (EK) of New South Wales, Australia||This species is based on a poorly preserved caudal vertebra that could belong to any one of several types of theropods|
|"Zanclodon" cambrensis (?N.D.) Newton, 1899||Rhaetian (LTr) of Wales||Based on a partial jaw, this animal was for a long time assigned to Megalosaurus. However, it appears to be closer to the coelophysoids than to the tetanurans. It could be indeterminate.|
Neotheropoda: This is getting into the more derived theropods, and starts off with a split between the coelophysoids and the other theropods, followed closely by the splitting-off of Ceratosauria.
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