One more trip to the well... In the spirit of Addendum II, here is my own compilation of undescribed dinosaurs. I am deliberately avoiding repeating entries from the 1982 list (sorry, "Thotobolosaurus" [2020/04/19: now Kholumolumo], Archbishop, Cleveland-Lloyd ankylosaur, and Monoclonius recurvicornis). In the spirit of that list, I full expect some of these to be named next week and some to be still hanging around, say, thirty-three years from now, like some from 1982 are still waiting in 2015. This is not an exhaustive list, but more of a "greatest hits". It is biased to reports with some history behind them, and also biased to reports that I think will eventually be substantiated, so there's none of the "[random place] [random dinosaur represented by a single bone]". Let me know if they ever get around to "Ngexisaurus".
"Shake N Bake" theropod: this is a coelophysoid from the Lower Jurassic Kayenta Formation of Arizona, represented by fifteen or more individuals. It goes back a few decades, having first appeared as putative juveniles of Syntarsus kayentakatae (which itself is now is in need of a genus to call home). The Theropod Database has a good summary of the history, specimens, and bibliography.
The "Saints and Sinners" theropod: another coelophysoid, known from another group of individuals, this animal was found in the Lower Jurassic Nugget Sandstone of northeastern Utah. The Nugget Sandstone is one of these giant erg (dune sea) formations with historically little in the way of body fossils, making a gaggle of dinosaurs particularly noteworthy. It was first reported in 2010, as a large and a small species, but now only one is thought to be represented. Most notice has come by way of SVP abstracts, but this form does make an appearance in one longer work (Chure et al. 2014). "Saints and Sinners", by the way, is a reference to the name of the quarry.
The "saltriosaur": "Saltriosaurus" is a basal tetanuran from Lower Jurassic rocks of Italy, known primarily from parts of the anterior torso and arms. It was first publicized in 2000, and has since made cameo appearances in discussions of Italian dinosaurs. It has both an entry in the Theropod Database and on Wikipedia.
[Update, 2018/12/19: This is now Saltriovenator zanellai.]
"Das Monster von Minden": this is a German tetanuran from Upper Jurassic rocks, known from skull bones and spare parts (a couple of verts, an ilium, etc.). It is most famous for being large, although in actual fact it was probably more Allosaurus-ish in size. Like "Saltriosaurus", it too has a Wikipedia entry, which just goes to show that all that really counts in this world is to be large, toothy, and mysterious.
[Update, 2016/8/31: We have a name now, Wiehenvenator albati, plus freely available description (here). And no, it's still not super-gigantic.]
Dinosaur National Monument Allosaurus: Gee, it feels strange to be circumspect when everyone and their grandmother is aware of the proposed name of the yet-to-be-formally-described Allosaurus species discovered at Dinosaur National Monument. What do I care? I spent years spelling "Ceratopsidae" "Ceratopidae" just because it should have been spelled that, didn't I? Well, anyway, it's a fine specimen. The Theropod Database again has the best summary, albeit buried within Allosaurus fragilis because it is considered a synonym there.
[Update, 2020/1/24: Allosaurus jimmadseni has made its official debut.]
The many unnamed species of Daspletosaurus: well, okay, you're basically dealing with two, the one from the Dinosaur Park Formation and the one from the Two Medicine Formation. Currie (2003) discusses both. Daspletosaurus the genus is apparently widespread in time and space, but D. torosus the type species is rather more limited. Incidentally, what was once considered a possible species from New Mexico was later named Bistahieversor sealeyi.
[Update, 2017/3/30: The Two Medicine species is now named Daspletosaurus horneri.]
"Saltillomimus": this is an ornithomimid from Upper Cretaceous rocks of Mexico. It is known from several individuals, with the first remains found in 1998. Postcranial bones are known, primarily from the hind limb. You might have chosen "Grusimimus" for this spot, and you wouldn't have been wrong, either. Ornithomimosaurians aren't bad at taxonomic hide-and-seek.
"Fake Oviraptor" or Citipati sp., ol' 100/42: this is the oviraptorid used to stand in for Oviraptor during the late '80s and '90s. You may remember its classical good looks in such books as "Predatory Dinosaurs of the World". One slight problem is a touch of "Nurosaurus syndrome": it spends too much time in traveling exhibition. Jaime Headden at The Bite Stuff recently featured a detailed article on this specimen, so familiar yet so out of reach.
Morrison Formation troodontid: also known informally as "Lori" and the somewhat less euphonious WDC DML 001, the Morrison troodontid is represented by a fairly complete skeleton. Somewhat of more notable import is that it is a troodontid dinosaur from the Upper Jurassic. (This would have been more significant a few years ago, before we had things like Anchiornis, but still, Morrison troodont!) "Lori" made a splash at the 2005 SVP and then went into seclusion. Here's hoping for a speedy reappearance!
[Update, 2019/07/10: "Lori" has been described as Hesperornithoides miessleri.]
The Nova Scotia prosauropod: from the depths of the Lower Jurassic McCoy Brook Formation comes a... fairly mild-mannered basal sauropodomorph. Such beasts have been reported from the formation since 1986, but that early find appears to be a Protosuchus instead, per Fedak (2007). Instead, I refer to a massospondylid sauropodomorph found in 1997 and described in the same dissertation. It somehow has a Wikipedia entry.
"Gyposaurus" sinensis: long considered a juvenile Lufengosaurus, this basal sauropodomorph from the Lower Jurassic Lufeng Formation of China is in need of re-evaluation. It sometimes travels under the name "Gripposaurus".
French Bothriospondylus madagascariensis: this is the lengthy alias given to a partial skeleton from Upper Jurassic rocks of eastern France. It's been known since 1934, and for some substantial part of that time the genus and species have been questioned. Aside from the issues true B. madagascariensis has, there's also the unfortunate business of the species being tied to Bothriospondylus in the first place, given that Bothriospondylus is an elaborate practical joke Richard Owen came up with as another way to torment his enemies (see also: most species of Cetiosaurus). A brief recent description can be found in Mannion (2010). (Anyway, a French B. madagascariensis is just a contradiction in terms, when you get right down to it.)
[Update, 2017/05/02: it has been renamed Vouivria damparisensis.]
"Neosodon": True Neosodon is one of many obscure tooth taxa, albeit with a slight bit of interest because it may be a turiasaur. "Neosodon" is used here as shorthand for an unnamed large French camarasaurid (Le Loeuff et al. 1996), which, come to think of it, also sounds like a turiasaur.
Some kind of resolution to the many, many species of Mamenchisaurus and Omeisaurus, and a few friends and neighbors: the Sauropoda of the Middle and Late Jurassic of China is a Gordian knot made up of writhing sauropod necks and tails. Someday, someone is going to pull a Tschopp et al. on them, and many surprises will be had. Until such time, I leave the following list for consideration (omitting a few wildcat taxa like Tienshanosaurus and Protognathosaurus):
Omeisaurus junghsiensis Yang 1939
Mamenchisaurus constructus Yang 1953
Omeisaurus changshouensis Yang 1958
Mamenchisaurus hochuanensis Yang and Zhao 1972
Omeisaurus fuxiensis Dong et al. 1983 (not the same as Zigongosaurus fuxiensis Hou et al.1976)
Omeisaurus tianfuensis He et al. 1984
Omeisaurus luoquanensis Li 1988
"Omeisaurus zigongensis" Tanimoto 1988
Mamenchisaurus sinocanadorum Russell and Zheng 1993
"Omeisaurus gongjianensis" Zhang and Wei 1995
Mamenchisaurus anyuensis He et al. 1996
Mamenchisaurus youngi Pi et al. 1996
"Mamenchisaurus guangyuanensis" Zhang et al. 1998
Mamenchisaurus jingyanensis Zhang et al. 1998
"Mamenchisaurus yaochinensis" He et al. 1996 vide Dong 1999
Omeisaurus maoianus Tang et al. 2001
Mamenchisaurus yunnanensis Fang et al. 2004
Omeisaurus jiaoi Jiang et al. 2011
"Nurosaurus": this large Lower Cretaceous sauropod from China is an exhibition special: it's never accessible for description, and the amount of plaster employed to make it presentable is unknown. The name, which varies in spelling, appeared in print by 1991. It has sometimes been described as "in press", so I suppose it is possible that a formal description lurks in an obscure regional Chinese source, or even that it was described under a different name. In the meantime, additional information can be found at Paleofile and Wikipedia.
National Geographic titanosaur: on page 130 in the December 1997 edition of National Geographic (Shreeve 1997), there is a photo of a titanosaurid skull. Accompanying text indicates the presence of pelvic bones and presacral vertebrae as well. It came from Rincón de los Sauces in Chubut. There is a name floating about, but I will refrain from including it.
[Update, 2016/04/27: the name that had been floating around, Sarmientosaurus, has been published. One thing bothers me, though: I thought there was supposed to be more of it than the head and some of the neck. Maybe there were two titanosaurs; close reading of the old article suggests as much. The final species name chosen, musacchioi, differs from the old informal species name of "splendens".]
Kayenta Formation heterodontosaurid: this little guy was found in 1981 and has existed on the fringes of ornithischian papers ever since. It is described in a fair amount of detail in Sereno (2012), which also figures the lower jaw. Apparently it is represented by "complete upper and lower dentitions, many other portions of the skull, vertebrae from all portions of the axial column, and portions of fore and hind girdles and limbs" from a subadult individual (Sereno 2012).
Suncor ankylosaur: the Suncor ankylosaur is a glorious articulated partial ankylosaur specimen discovered at a Suncor oil sands mine in Alberta, in March 2011. (I'm sorry, but articulated ankylosaurs with their armor in place are for my money the most spectacular dinosaur specimens.) This was prophesied, sort of, in a pop dinosaur book of the 1980s: "Even greater discoveries may come from farther north. Early Cretaceous leaves lie here, pickled (not fossilized) by Alberta's oily tar sands. One day, scientists may also find the whole, pickled body of a dinosaur more than 100 million years old." (Lambert 1983:223; the section is rephrased in Lambert 1990). Anyway, here's how it looked in January 2014, and another photo from March 2015 (the "granite" is poetic license, as explained in the replies).
[Update, 2017/08/03: the Suncor ankylosaur has been published as the nodosaur Borealopelta markmitchelli.]
"Gongbusaurus" wucaiwanensis: from the sublime to the more mundane, we arrive at this small ornithischian from the Upper Jurassic of China. It was first described in 1989 as a second species of Gongbusaurus. The type species of Gongbusaurus, G. shiyii, is only known from teeth, whereas "G." wucaiwanensis is known from two fragmentary skeletons. The "fragmentary" part is probably what's holding it back. You may encounter it as "Eugongbusaurus".
Proctor Lake hypsilophodont: the Proctor Lake hypsilophodont was discovered in 1985 and made its debut in 1989 (Winkler and Murry 1989). It is represented by the remains of numerous individuals of various ages from the Upper Cretaceous Twin Mountains Formation. Given the presence of numerous juveniles, there are interesting paleobiological aspects at play as well. [Update, 2019/03/12: the Proctor Lake hypsilophodont is now Convolosaurus marri.]
High-spined Cedar Mountain iguanodont, a.k.a. the Dalton Wells iguanodont: the backstory here is straightforward. It's an iguanodont from the Dalton Wells Quarry featuring high spines, and it's undescribed. There is a slight twist, in that Iguanodon ottingeri is also an iguanodont from the Dalton Wells Quarry, and there doesn't seem to be anything drastic keeping the high-spined iguanodont from synonymy. Maybe our high-spined friend is Iguanodon ottingeri. At any rate, Cedar Mountain Formation taxa have proliferated like rabbits since the mid '90s, and we've actually built up quite a stockpile of unnamed genera and species, particularly sauropods. Accept this high-spined iguanodont as symbolic.
The "sabinosaurio": also known as PASAC-1 or the Sabinas hadrosaurid, this is a saurolophine hadrosaur represented by a skeleton recovered in 2001 from the vicinity of Sabinas in Coahuila, Mexico. Much of the skeleton is present, with the unfortunate exception of a significant part of the face, which helps to explain why it is going along without a formal name. It has received extended attention in Kirkland et al. (2006) and Prieto-Márquez (2014). It has often been compared to Kritosaurus, although this is tentative with the absence of those facial bones (the skull on the mounted skeleton is based on a different specimen). At around 11 m long it's also quite a healthy-sized specimen.
"Microcephale": Last but not least, although certainly the smallest, is a tiny pachycephalosaur known from cranial material from the Dinosaur Park Formation of Alberta. First mentioned to a wide audience in Sereno (1997), it was apparently supposed to be described in Sereno's contribution to "The Age of Dinosaurs in Russia and Mongolia" (2000) at one point, but although that book has much useful and interesting information, it does not contain anything that could be construed as a description of "Microcephale". Nor did it make an appearance in the 2005 Dinosaur Park volume, which otherwise included everything known to mortal man about the DPF. After its non-description, the tiny pachycephalosaur faded away, to be unexpectedly revived in 2009 with the appearance of another tiny pachycephalosaur in a documentary, this one described as "cat-sized" with a top-hat-like dome. This one was apparently called "Mycocephale", which would mean "mushroom [or fungus] head", presumably a reference to the shape of the dome. This sounds suspiciously like "Microcephale", down to the fact that all you have to do to interchange the names when speaking is to swallow the "r".
Chure, D. J., G. F. Engelmann, B. B. Britt, and T. R. Good. 2014. It's not your parents' erg deposit anymore: fossil management implications of a paleontological study of the Nugget Sandstone in northeastern Utah. Dakoterra 6:148–162.
Currie, P. J. 2003. Cranial anatomy of tyrannosaurids from the Late Cretaceous of Alberta. Acta Palaeontologica Polonica 48(2):191–226.
Fedak, T. J. 2007. Description and evolutionary significance of the sauropodomorph dinosaurs from the early Jurassic (Hettangian) McCoy Brook Formation. Dissertation. Dalhousie University, Halifax, Nova Scotia.
Kirkland, J. I., R. Hernández-Rivera, T. Gates, G. S. Paul, S. Nesbitt, C. I. Serrano-Brañas, and J. P. Garcia-de la Garza. 2006. Large hadrosaurine dinosaurs from the latest Campanian of Coahuila, Mexico. New Mexico Museum of Natural History and Science Bulletin 35:299–315.
Lambert, D. 1983. A field guide to dinosaurs. Avon Books, New York, New York.
Lambert, D. 1990. The dinosaur data book. Avon Books, New York, New York.
Le Loeuff, J., E. Buffetaut, and C. Merser. 1996. [Discovery of a Tithonian sauropod dinosaur in Charente (western France)]. Géologie de la France 2:79–81. [French with English abstract]
Mannion, P. D. 2010. A revision of the sauropod dinosaur genus 'Bothriospondylus' with a redescription of the type material of the middle Jurassic form 'B. madagascariensis'. Palaeontology 53(2):277–296.
Prieto-Márquez, A. 2014. Skeletal morphology of Kritosaurus navajovius (Dinosauria: Hadrosauridae) from the Late Cretaceous of the North American south-west, with an evaluation of the phylogenetic systematics and biogeography of Kritosaurini. Journal of Systematic Palaeontology 12(2):133–175.
Sereno, P. C. 1997. The origin and evolution of dinosaurs. Annual Review of Earth and Planetary Science 25:435–489.
Sereno, P. C. 2012. Taxonomy, morphology, masticatory function and phylogeny of heterodontosaurid dinosaurs. ZooKeys 226: 1–225.
Shreeve, J. 1997. Uncovering Patagonia's lost world. National Geographic 192(6):120–137.
Winkler, D. A., and P. A. Murry. 1989. Paleoecology and hypsilophodontid behavior at the Proctor Lake dinosaur locality (Early Cretaceous), Texas. Pages 55–61 in J. O. Farlow, editor. Paleobiology of the dinosaurs. Geological Society of America, Boulder, Colorado. Special Paper 238.