Dinosaurs

   O.K., now we get into the fun stuff.  How this is going to work is I will have a sort of "cladogram" (it's not a real cladogram, wherein the characters pertaining to each taxon are run through computer models to test taxon relationships, but more a sort of composite of well-regarded trees), with various clades, some of which I'll expand on on different pages. Any dinosaurs falling out at a given clade will be profiled below the cladogram (you'll be able to tell the dinosaurs from the classification level names because the dinosaur names will be in italics). Further navigation can be done with the table at the bottom of the page.
    I'd like to take a moment and briefly (for now; I hope to expand later) place dinosaurs among the reptiles. Dinosaurs, including birds, are members of Archosauria, a group of reptiles also including the crocodilians and allies (often called Crurotarsi, or alternately Pseudosuchia). This group in turn is part of Diapsida, which also includes the lepidosauromorphs, which include the lizards, snakes, and mosasaurs, a group of marine reptiles from the upper Cretaceous usually allied with the monitor lizards, but sometimes considered closer to snakes. Diapsids are known by their two temporal fenestrae, among other things. Diapsids together with Anapsida [turtles] are the main members of Reptilia.
    Other famous prehistoric reptiles (and "reptiles") include the pterosaurs, ichthyosaurs, plesiosaurs and allies, "thecodonts," and things like Dimetrodon. Pterosaurs typically sort out as the closest of these groups to dinosaurs, although there's still the chance that they turn out to be something wacky, possibly not even archosaurians. Ichthyosaurs, famous for their close resemblance to dolphins, have an uncertain placement, due to the general lack of good remains from very basal members. In the past, they were sometimes classified with the plesiosaurs and their allies in Euryapsida (again due to temporal fenestrae), a group which turned out to be unnatural. The plesiosaurs and their allies, including the nothosaurs (which looked broadly like less marine plesiosaurs) and placodonts (unusual, heavily-armored forms with robust teeth for crushing shells) are classified in the Sauropterygia, which likely is a subgroup of Diapsida. "Thecodontia" is an old name for an assemblage of archosaurs that were linked by their not being anything else; the ancestors of the derived archosaurian lineages were often considered simply archosaurs, for example the "lagosuchids." Animals like Dimetrodon (which greatly predated the dinosaurs, but still finds its way into "dinosaur" toy sets; it must be in its contract) are not true reptiles, but closer to mammals, hence the old phrase "mammal-like reptiles."
    Eventually, I'd like to take the information in the preceding two paragraphs and put it on a new page in a much expanded form, for one because it's kind of unfair to just throw the dinosaurs out without giving a sense of their background, and second because the other animals (I find pterosaurs and plesiosaurs particularly interesting) are worthy of it in their own right. I hope I haven't been too confusing in this short introduction.
    Meanwhile...  

<--Dinosauromorpha
      |--Lagerpetidae
      |   |--Dromomeron
      |   `--Lagerpeton
      `--Dinosauriformes
           |--Marasuchus
           `--+--Lewisuchus
                `--+--Asilisaurus
                     `--+--Silesauridae
                          |     |--Diodorus
                          |     |--Eucoelophysis
                          |     |--Ignotosaurus
                          |     |--Lutungutali
                          |     |--Sacisaurus
                          |     `--Silesaurus
                          `-- Dinosauria
                                |--Saurischia
                                |   |  Saurischia incertae sedis:
                                |   |  Herrerasauridae
                                |   |   |--Staurikosaurus
         
                      |   |   `--+--?Chindesaurus
                                |   |        |--Herrerasaurus
                                |   |        `--Sanjuansaurus
         
                      |   |-->Theropoda
                                |   `-->Sauropodomorpha
                                `-->Ornithischia (aka Predentata)

Poor Remains That May Come From Dinosaurs/Dinosauromorphs, But For Which The Evidence Is Equivocal At This Time: You may remember the spurt of "Triassic tooth ornithischians" in the 1990s and early 2000s. The flagship genus was Revueltosaurus, which ungratefully turned out to be a pseudosuchian after the skull was found (and a rather odd one to boot, related to the armored, herbivorous aetosaurs).. Pseudosuchians, despite the name ("false croc"), actually include crocs, although the name was originally intended for a variety of Triassic archosaurs that were similar to but not crocs. Since then, Crosbysaurus, Lucianosaurus, Protecovasaurus, and Tecovasaurus have been shown to be probably valid, but also only classifiable to Archosauriformes i.s. (so pretty far from dinosaurs), and probably not ornithischian dinosaurs (they lack a cingulum on the teeth, a sort of ridge or swelling at the base of the crown), while Pekinosaurus and Galtonia are regarded as Revueltosaurus sp., and the newly-minted Krzyzanowskisaurus hunti, a former species of Revueltosaurus with an imitation cingulum, now regarded as possibly pertaining to Revueltosaurus (again). Azendohsaurus, first thought to be a "fabrosaurid", then a prosauropod, is also not dinosaurian.

Taxon or Taxa: Time/Place: Comments:
?Avipes dillstedtianus (N.D.) Huene, 1932 MTr of Germany Although often considered to be a small dinosaur because the metatarsals it was named from appear to come from a digitigrade animal, it could equally well be a pterosaur, saltoposuchid crocodilian, or other digitigrade (walking on the toes) archosaurian. If it was a dinosaur, it was one of the earliest. A "lagosuchid"-like animal is probably the closest it was to Dinosauria.
Dravidosaurus blanfordi Yadagiri and Ayyasami, 1979 Coniacian (LK) of India Dravidosaurus spent the 1980s as the latest-known stegosaurid, but in the 1990s, restudy suggested that all was not well. In fact, reported skull and plate material was not seen, but material indicative of plesiosaurians, also known from the same locality. Dravidosaurus was chalked up as a plesiosaur. The relevant chapter of the second edition of The Dinosauria includes it as a stegosaurian, but, in a case of lengthy publication, was written before the reidentification as a plesiosaur despite being published several years later. Obviously, the solution to its identity requires more study of the material, and it would also help to have more material!
Oddly, mention has been made of possible later Indian stegosaurid material (see the dinosaur distribution chapter in the original Dinosauria, if you don't believe me).
"Iguanodon" exogyrarum (N.D.) Fritsch, 1878 (Ponerosteus) Cenomanian (LK) of the Czech Republic Also known as Ponerosteus (Olshevsky, 2000), this taxon is about as dubious as it gets. It is based on what may be a tibial endocast (a cast of the interior of the tibia), and is probably only considered dinosaurian because of size; it could conceivably have come from something else with a hollow long bone, like a bird or pterosaur. The translation of Ponerosteus says it all: "bad, worthless, or useless bone".
Lukousaurus yini Yang, 1948 (?N.D.) Hettangian-Sinemurian (EJ) of China This beast, based on a partial skull with distinctive preorbital horns, is likely some sort of basal pseudosuchian. Traditionally, it was thought to be a dinosaur; its antorbital fenestra shows some resemblance to Ceratosaurus' and the abelisaurids'.
Razanandrongobe sakalavae Maganuco, Dal Sasso, and Pasini, 2006 Bathonian (MJ) of Madagascar This archosaur, either a large crocodylomorph or a theropod, is known from a maxilla fragment with teeth. At this time, not enough is known to settle on one option.
Rhadinosaurus alcinus (N.D.) Seeley, 1881 early Campanian (LK) of Austria Although considered at times a nodosaurid and a possible synonym of the ever-popular Struthiosaurus, it is not known for certain if this taxon is even dinosaurian (crocodilian has been one alternative). It is based in part on ankylosaur-like fibulae misidentified as femurs.
?Spondylosoma absconditum (N.D.) Huene, 1942 Ladinian (MTr) of Brazil I thought I was done with this thing, but it keeps popping back up. It's based on postcranial material, including cervicals, dorsals, sacrals, ribs, and a humerus, that show a mix of dinosaurian and non-dinosaurian (rauisuchians, closer to crocs) characters. It could be a silesaur, but is best considered an indeterminate archosaur.
?"Stegosaurus" madagascariensis (N.D.) Piveteau, 1926 middle Maastrichtian (LK) of Madagascar Not Stegosaurus, as originally described, the teeth this species is based on could belong to an herbivorous crocodyliform or, less likely in my opinion, an ankylosaur.
?"Tanystropheus" posthumus (N.D.) Huene, 1908 (Tanystrosuchus) mid Norian (LTr) of Germany Also known as Tanystrosuchus, this is just an obscure indeterminate archosaur based on a caudal, perhaps from a theropod or shuvosaurine rauisuchian.
Teyuwasu barbarenai (N.D.) Kischlat, 1999 early Norian (LTr) of Brazil Based on a right femur and tibia originally referred to a non-dinosaur, this taxon bears some resemblance to Marasuchus and Herrerasaurus. It is probably some kind of dinosauriform.
?"Thecodontosaurus" subcylindrodon (N.D.)  Huene, 1907-08 Norian-Rhaetian (LTr) of Germany This may or may not be dinosaurian. It is based on a tooth.

Dinosauromorpha i.s.: This level is just outside of Dinosauria, and is primitive in several ways. For example, the animals here still have armor plating down the midline of their backs (Ceratosaurus either retains this or converges [has a similar character evolved from different processes]), sacra with less than three vertebrae contributing, and very underdeveloped pelvic bones compared to true dinosaurs (the pubis of Marasuchus is very short, and the ilium is still small).    

Taxon or Taxa: Time/Place: Comments:
Lagosuchus talampayensis (N.D.) Romer, 1971 Ladinian (MTr) of Argentina This animal was probably very much like Marasuchus (understandably, since this is basically Marasuchus without valid characteristics preserved in its type remains). Lagosuchus was dumped because its type material was considered too poor to provide any anatomical characters that could be called uniquely its own. Good material that was assigned to it earlier that did provide such characters was renamed Marasuchus.
Saltopus elginensis Huene, 1910 Norian (LTr) of Scotland This small animal was frequently illustrated in the past, giving the idea that we know more about it than we do. The type material, including back, tail, shoulder, pelvic, and limb material, is poorly preserved. Saltopus appears to be more derived than lagerpetids and "lagosuchids," and may be related to the silesaurids.

Lagerpetidae:  

Taxon or Taxa: Time/Place: Comments:
Dromomeron: Irmis, Nesbitt, Padian, Smith, Turner, Woody, and Downs, 2007 D. romeri (type) Irmis, Nesbitt, Padian, Smith, Turner, Woody, and Downs, 2007 middle or late Norian (LTr) of New Mexico Based on a femur, Dromomeron appears to be closest to Lagerpeton. What makes it even more interesting is that it was found in a quarry that also included the bones of an unnamed animal like Silesaurus, Chindesaurus, and an unnamed coelophysoid, which shows that early dinosaurs hadn't managed to kick out their cousins immediately, and that early offshoots from the dinosaur line had diversified and prospered from their roots farther back in the Triassic. In addition, the faunal changeover, including loss of these early groups, may have taken place at different points in time in different locations. Further searching has turned up more of D. romeri, including a partial articulated skeleton, and a second species, D. gregorii.
D. gregorii is known from Texas and Arizona, from femora and tibiae. It's somewhat older than D. romeri. D. gregorii is probably older than 220 million years, and D. romeri is closer to 210 million years; blame it on the long Norian for making them appear to be closer.
D. gregorii Nesbitt, Irmis, Parker, Smith, Turner, and Rowe, 2009 early Norian (LTr) of Texas and Arizona
Lagerpeton chanarensis Romer, 1971 Ladinian (MTr) of Argentina This is an unusual little animal. It's a rather obscure creature similar to Marasuchus, but not as well known. Its feet are unusual in that the fourth toe and metatarsal are longer than the other toes and metatarsals, unique among dinosauromorphs.

Dinosauriformes: I'm just throwing this term in for the sake of completeness and accuracy, but it doesn't really add much to what we're doing here, given how few animals are known at the base of the dinosaur lineage.

Taxon or Taxa: Time/Place: Comments:
Marasuchus lillioensis Sereno and Arcucci, 1994 (originally Lagosuchus lillioensis Romer, 1971) Ladinian (MTr) of Argentina This was a small (half-meter scale, or if you absolutely refuse to deal in such units, less than a foot and a half in length, most of which is tail), agile, possibly leaping dinosauriform. It was probably a small-game hunter.
Lewisuchus admixtus Romer, 1972 Ladinian (MTr) of Argentina Based on a partial skeleton consisting of a partial skull and jaws, and some of the front half of the postcranial skeleton, big-headed Lewisuchus may be another basal dinosauromorph (and possibly the same as Pseudolagosuchus, although unfortunately the known material does not overlap, as is par for the course). Some of the material, including jaw and foot and ankle remains, actually belongs to a croc-line archosaur.
Asilisaurus kongwe Nesbitt, Sidor, Irmis, Angielcyzk, R. Smith, and Tsuji, 2010 Anisian (MTr) of Tanzania Pushing back the record for dinosauriforms into the early part of the Middle Triassic, Asilisaurus is a silesaurid known from a bonebed including the remains of at least twelve individuals. Almost all of the skeleton is represented, with parts of the skull, forearms, and hands being the primary sections absent. If you think about it, it's not surprising to have early MTr dinosauriforms, given our growing crop of such animals, but proposing existence and having the remains are two different things, and as you can guess, it's hard to beat the latter.

Dinosauriformes i.s.:

Taxon or Taxa: Time/Place: Comments:
Nyasasaurus parringtoni Nesbitt, Barrett, Werning, Sidor, and Charig, 2012 late Ladinian (MTr) of Tanzania Nyasaurus may be the oldest known dinosaur, or perhaps one of the closest relatives to the group. It is based on three presacrals, three sacrals, and a humerus with dinosaurian features. 
Nyasasaurus
may hold the record (in the dinosaur/dinosaur relative category) for the longest time between someone coming up with a name and that name being formally employed. It first showed up in Charig's 1956 dissertation, and from time to time would pop up in books, sometimes as "Nyasaurus". (I don't think there are any others of such great vintage out there; I know of one from the 1970s, but outside of Zhao's crop from the 1980s and the Japanese names of 1990, which were kind of unintentionally conceived anyway, everything else outstanding is late 1990s and younger).
Pseudolagosuchus major Arcucci, 1987 (?Lewisuchus) Ladinian (MTr) of Argentina Pseudolagosuchus historically is something of a dinosauromorph enigma. It is not yet well known, and has been considered as a "lagosuchid" (hence the name), "staurikosaurid", very early theropod, and silesaurid. It is known from a handful of specimens, mostly of vert and hindlimb material.
"Thecodontosaurus" alophos (?N.D.) Haughton, 1932 (?Nyasasaurus) late Ladinian (MTr) of Tanzania "Thecodontosaurus" alophos is represented by five vertebrae from an animal very similar to or synonymous with Nyasasaurus. The cervical vertebrae have some similarities to those of theropods.

Silesauridae: Silesaurids appear to persist into the late Norian, having been found in mid-late Norian rocks of Poland that have also yielded herresaurids and neotheropods.

Taxon or Taxa: Time/Place: Comments:
Diodorus scytobrachion Kammerer, Nesbitt, and Shubin, 2011 ?Carnian-Norian (LTr) of Morocco Diodorus is based on a partial lower jaw, with a few referred elements (teeth, two humeri, an MT, and a femur). It appears to be fairly derived among silesaurids. Among its contemporaries is the former basal dinosaur Azendohsaurus.
Eucoelophysis baldwini Sullivan and Lucas, 1999 early Norian (LTr) of New Mexico The old entry for this animal ran like this: "Eucoelophysis is based on partial remains including 2 dorsal verts, two caudals, a partial shoulder girdle, most of a pelvis, and hindlimb material. It is also tied up in the Coelophysis saga; in the late 1980s and early 90s, a challenge was mounted on the validity of Coelophysis because some paleontologists claimed this specimen showed no characters that were distinctive, while others claimed it did. Rioarribasaurus colberti was substituted for a while for the hundreds of Ghost Ranch specimens, but then Coelophysis was officially redefined to have as its new type a Ghost Ranch skeleton, leaving the original type homeless. Part of the original type of Coelurus longicollis (not the current lectotype), one of the three species Cope named which were later generally considered to be within the limits of variation of C. (later Coelophysis) bauri, was assigned to this species, and the other fragmentary original types were considered possibly referable. Additional material, including skull and postcranial material, may be known. It is slightly older than Coelophysis."
The historical stuff still holds; there was a time in the recent past when the taxonomy of Coelophysis was a divisive issue (now it's moved on to "Syntarsus"), and this was one solution. However, the animal in question has ungratefully turned out to be something much more like Silesaurus, as a dinosauriform. Thus, we have the irony that comes of including classification details in an animal's name: "true Coelophysis" is actually not particularly closely related to the Coelophysis we're used to (apparently the "false Coelophysis"). The other moral of the story is to watch out when dealing with Triassic reptiles.
Ignotosaurus fragilis Martínez, Apaldetti, Alcober, Colombi, Sereno, Fernandez, Santi Malnis, Correa, and Abelin, 2013 middle Carnian (LTr) of Argentina Ignotosaurus is a silesaurid known from an ilium (this is a common theme with this group, but it beats being known from teeth).
Lutungutali sitwensis Peecock, Sidor, Nesbitt, Smith, Steyer, and Angielczyk, 2013 Anisian (MTr) of Zambia The first unique dinosauriform from Zambia, Lutungutali is based on a partial pelvis and four caudals. It is noted for the tall blade of the ilium, which inspired the genus name (from the Bemba language). It is more derived than other known Middle Triassic silesaurids.
Sacisaurus agudoensis Ferigolo and Langer, 2006 Norian (LTr) of Brazil At first mooted as a possible basal ornithischian, due to an apparent incipient predentary composed of two unfused beak elements, one on each side of the lower jaw, recent discoveries like Silesaurus indicate that it's really a dinosauriform. Remains from several individuals are known.
Silesaurus opolensis Dzik, 2003  early Norian (LTr) of Poland Silesaurus is one of the most interesting and unusual dinosaur-type animals to have come out in the last few years. I say "dinosaur-type" because it is very basal, if at all a dinosaur. The short ilium and closed acetabulum are basal features, and the neural spines remind me of various "thecodonts," while the long forelimbs are like the "lagosuchids," but the pubes are very elongated compared to non-dinosaurian archosaurians, and the lower jaw has a small beaked prominence, possibly related to a predentary. Silesaurus may be a very basal ornithischian, or some dinosauromorph that happened to have a beak, or could even represent a basal prosauropod-ornithischian relative, reviving Phytodinosauria. It is described as more derived than Pseudolagosuchus, but more basal than Dinosauria. Several individuals are known, with enough material to get a very clear idea of the skeleton (except the hand). Recent reports put it as the sister group to Saurischia+Ornithischia, although it could still be an ornithischian.
I wonder if this animal is responsible for earlier reports of Thecodontosaurus from Poland.

Silesauridae i.s.:

Taxon or Taxa: Time/Place: Comments:
Technosaurus smalli Chatterjee, 1984 Norian (LTr) of Texas Based on a poorly-associated partial skeleton that was first assigned to basal Ornithischia with part of a jaw later sent to Sauropodomorpha, the true identity of this animal is now known. Restricted to the premaxilla and dentary, it seems to be related to Silesaurus; a posterior mandible chunk belongs to Shuvosaurus, which is most certainly not a dinosaur.

Dinosauria i.s.: The taxa listed here are mostly very dubious, to the point where they cannot be assigned to a higher level. Sometimes this is due to poor material, and sometimes this is due to the fact the material does not belong to one kind of dinosaur, but to at least two different types, creating what is called a chimera (or chimaera, if your taste runs to additional "a"s).. Some of the chimerical animals listed, like Sanpasaurus, could become better classified if the remains were to be officially limited to one or the other animals present in the remains, but others may be doomed to an eternity in the paleontological wastebasket.

Taxon or Taxa: Time/Place: Comments:
"Agathaumas milo" (N.N.) Cope, 1874 late Maastrichtian (LK) of Colorado Usually tossed into Edmontosaurus without discussion, "Agathaumas milo" was kind of a taxonomic stillborn. Cope never properly described it, and assigned it to Hadrosaurus occidentalis (his reassignment of Thespesius) soon after coming up with the name. It is based on a sacral centrum and part of a tibia.
Apatodon mirus (N.D.) Marsh, 1877 ?Kimmeridgian (LJ) of Rocky Mountain region, USA Apatodon is a name Marsh came up with for something he thought was a Mesozoic pig jaw, but which was quickly shown to be an eroded dinosaur vertebra (the neural spine looked like a tooth). Sometimes it gets mixed up with Allosaurus for no particular reason.
"Astrodon" pusillus (N.D.) Lapparent and Zbyszewski, 1957 Kimmeridgian (LJ) of Portugal First thought to be a sauropod, then a juvenile stegosaurid perhaps pertaining to Dacentrurus armatus, this species is based on unpromising remains including a few vert centra, a partial femur, metapodials, and some miscellaneous bones.
Caseosaurus crosbyensis Hunt, Lucas, Heckert, and Lockley, 1998 (?Chindesaurus) early Norian (LTr) of Texas Casesaurus is based on an ilium once referred to Chindesaurus and may well be synonymous with it.
"Omosaurus": "O." vetustus (N.D.) Huene, 1910 Bathonian-Callovian (MJ) of England Both of these species are based on partial femora that have long been tossed off as belonging to juvenile stegosaurids, but which could just as well have belonged to a sauropod.
"O." phillipsi (N.D.) Seeley, 1893 early-middle Oxfordian (LJ) of England
"Poekilopleuron" schmidti (N.D.) Kiprijanov, 1883 Cenomanian (LK) of western Russia The remains named "Poekilopleuron" schmidti are usually tossed off as bones of an indeterminate large theropod, but may not even be dinosaurian. One element resembles a titanosauriform metacarpal, and other pieces may have come from marine reptiles.
Sanpasaurus yaoi (N.D.) Yang, 1946 EJ of China This animal's type remains may come from a sauropod and iguanodontian that had their remains mingled after death. The major parts are 20 isolated verts, scapulae, forelimbs, and parts of the hindlimbs, which arrived to their museum in a jumbled state. It was described as an iguanodontid, but some researchers have suggested that parts of it, especially the forelimbs, may be from a juvenile sauropod.
?Symphyrophus musculosus (N.D.) Cope, 1878 Kimmeridgian (LJ) of Colorado A loser in the Marsh-Cope wars, this taxon has been considered to be a synonym of Camptosaurus, but may not be dinosaurian.
Thecospondylus horneri (N.D.) Seeley, 1882 Barremian (EK) of England Although originally called a small theropod, the internal cast of the sacrum (hip verts) that makes up the holotype is far too big for this. Based on size and contemporaries, it's doubtless dinosaurian.
Tichosteus (N.D.): Cope, 1877 T. lucasanus (N.D.) (type) Cope, 1877 Kimmeridgian (LJ) of Colorado Forgotten casualties of the Marsh-Cope wars, these two species, based on vertebrae, may be theropod, ornithopod, or neither. While it is usually my policy to separate dubious species from the genus to which they were originally assigned, in this case there doesn't seem to be much of a point. Cope described them as sauropod; if anyone considers them nowadays, they are usually dashed off as possible ornithopod bones, although T. aequifacies could represent bones of the common Morrison turtle Glyptops.
?T. aequifacies (N.D.) Cope, 1877

Saurischia and Ornithischia:  Besides some basal forms, dinosaurs are traditionally divided into two groups based on hip anatomy: the saurischians, which had pelves with the pubis jutting away from the ischium; and the ornithischians, which had pelvises with the pubis paralleling the ischium (like in birds). The saurischians include the theropods and sauropodomorphs, while the ornithischians, also known as predentatans (Predentata is a much better name for Ornithischia, because it describes the predentary at the front of the jaw that "ornithischians" and only "ornithischians" have among dinosaurs, while dinosaurs beside "ornithischians", including dromaeosaurids, therizinosaurians, and, rather anticlimactically, birds, possess an analogue of the "bird-hip" for which Ornithischia is named) include a wide variety of beaked herbivores. Occasionally, someone has suggested that the sauropodomorphs and the ornithischians go together (Phytodinosauria), but this appealing idea has little evidence for it.

Saurischia i.s.: Herrerasauridae: The herrerasaurids have bounced around that space between basal Theropoda and just outside of Dinosauria for years now. The most stable thing we can say is that they appear to be basal saurischians. One of the unusual aspects of this group is the very birdlike elements combined with such primitive features as a four-fingered hand. Another odd character is the backshifting of the pubis, similar to, but not to the same extent, as that seen in ornithischians, dromaeosaurids, therizinosaurians, and birds.
    The earliest known dinosaur remains may belong to a herrerasaurid; a pubic boot from the Anisian-age (MTr) portion of the Moenkopi Formation in Arizona may have come from such a beast. Based on what we know about basal dinosaurs, they probably first radiated in the Middle Triassic, so this wouldn't be entirely surprising.

Taxon or Taxa: Time/Place: Comments:
Staurikosaurus pricei Colbert, 1970 earliest Norian (LTr) of Brazil Staurikosaurus is roughly contemporary with the Ischigualasto dinosaur fauna (including Eoraptor, Herrerasaurus, and Pisanosaurus), and seems to be intermediate in some ways between Eoraptor and Herrerasaurus, both in size and anatomy. It is not as well known as those two dinosaurs, and may turn out to be closer to the sauropodomorphs. 
?Chindesaurus bryansmalli Long and Murry, 1985 early Norian (LTr) of Arizona Early press releases called this a prosauropod and the earliest dinosaur, neither of which it turned out to be. This predator is possibly intermediate between Staurikosaurus and Herrerasaurus, and is usually grouped with the herrerasaurids, but is not actually known from particularly good material, and so will continue to lead a nomadic systematic existence at the base of Saurischia (or elsewhere; it may turn out to be closer to crocs).
Herrerasaurus ischigualastensis Reig, 1963 late Carnian (LTr) of Argentina This is the best known early ?theropod, by dint of its many known remains. It is usually thought to be the same as Ischisaurus cattoi and Frenguellisaurus ischigualastensis. Currently, it is known from one nearly complete skeleton, several partial skeletons, isolated remains, and several partial to nearly complete skulls.
Sanjuansaurus gordilloi Alcober and Martinez, 2010 late Carnian (LTr) of Argentina A contemporary of Herrerasaurus, Eoraptor, and basal sauropodomorphs Panphagia and Chromogisaurus, Sanjuansaurus is known from a partial skeleton (bit of maxilla, complete vertebral column from the axis to the rostral tail, scapulae, an ulna and radius, partial pelvis, femurs, tibiae, a few other odd bones). Unlike other herrerasaurids, the pubis points cranially.

Saurischia i.s.: Herrerasauridae i.s.:

Taxon or Taxa: Time/Place: Comments:
Frenguellisaurus ischigualastensis Novas, 1986 (?Herrerasaurus) late Carnian (LTr) of Argentina Frenguellisaurus is based on a partial skull, a cervical, and a few caudals. Its remains represent a large Ischigualasto herrerasaurid.
Ischisaurus cattoi Reig, 1963 (?Herrerasaurus) late Carnian (LTr) of Argentina Ischisaurus is known from two partial skeletons representing the majority of a skeleton and bits of the skull, from smallish herrerasaurids.

Saurischia i.s.:

Taxon or Taxa: Time/Place: Comments:
Agnosphitys cromhallensis Fraser, Padian, Walkden, and Davis, 2002 ?Norian-Rhaetian (LTr) of England A possible basal dinosaur, described as more derived than Eoraptor and Herrerasaurus (but interestingly, in the description all are considered basal to true dinosaurs), it is based on an ilium (with partially-perforated acetabulum and two sacrals), with maxilla, astragalus, humerus, and teeth referred to it. It has been misspelled as Agnostiphys and Agnosphytis in the past. The remains could be chimeric, with the maxilla being theropodan. 
Alwalkeria maleriensis Chatterjee and Creisler, 1994 (originally Walkeria maleriensis Chatterjee, 1987) early Norian (LTr) of India The material is intriguing (skull, vertebrae, and some hindlimb fragments), but poorly preserved and chimeric. It may be near Herrerasauridae, in part.
Eodromaeus murphi Martinez, Sereno, Alcober, Colombi, Renne, Montañez, and Currie, 2011 late Carnian (LTr) of Argentina Eodromaeus is a basal saurischian broadly similar to its contemporary Eoraptor, with some herrerasaurid-like characteristics and some Tawa-like characteristics. It was described as a basal theropod, but I've opted for a conservative assignment, as these basal forms tend to switch placements with each new publication. It is known from a nearly complete skeleton, with some other referred specimens. 
Guaibasaurus candelariai Bonaparte, Ferigolo, and Ribeiro, 1999 earliest Norian (LTr) of Brazil This dinosaur has jumped around the basal stems of the great dinosaurian lineages. It has been considered to be somewhere around Staurikosaurus and the rest of Herrerasauridae, and/or basal to the Theropoda/Sauropodomorpha split, or a basal theropod outside of the herrerasaurids, or a basal sauropodomorph in the family Guaibasauridae with several other basal forms. Remains of several individuals are known, including one partial articulated skeleton representing most of the body posterior to the neck; unfortunately, the skull remains unknown. The acetabulum shows little opening, but the fifth toe is reduced, with no phalanges.

 

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