August 25 , 2016

by Carnoferox

I decided to write a more detailed followup to my original blog post “Ten Obscure Dinosaurs”. Without further ado, here are ten more dinosaurs that you have probably never heard of.

10. “Capitalsaurus potens”

Distribution: Arundel Formation (District of Columbia, United States)

Scientific Classification: Dinosauria, Saurischia, Theropoda incertae sedis

Description: This indeterminate theropod was discovered in 1898 when a single caudal vertebra was found by workers installing a sewer in Washington, D.C. It was originally assigned to Creosaurus (junior synonym of Allosaurus) by Richard Lull in 1911. A decade later, Charles Gilmore reassigned it to Dryptosaurus. However, it is distinct from both of these taxa due to temporal differences. In 1990, Peter Kranz coined “Capitalsaurus” as an informal replacement genus. Lack of identifiable remains unfortunately prevents classification beyond Theropoda incertae sedis.

9. “Arkansaurus fridayi”

Distribution: Trinity Group (Arkansas, United States)

Scientific Classification: Dinosauria, Saurischia, Theropoda, Tetanurae, Coelurosauria incertae sedis

Description: In 1972, farmer J.B. Friday found the foot bones of this dinosaur on his land near Lockesburg, Arkansas. The bones were donated to the University of Arkansas, where Dr. James Quinn described them and assigned them to Ornithomimus. The fossils were redescribed by Rebecca Hunt in 2003, who found them distinct from Ornithomimus. Hunt created the new genus “Arkansaurus” for the remains and classified it as an indeterminate coelurosaur. “Arkansaurus” remains an informal name because of the minimal material, which some researchers do not consider enough to warrant a new genus.

8. Embasaurus minax

Distribution: Neocomian Sands (Kazakhstan)

Scientific Classification: Dinosauria, Saurischia, Theropoda incertae sedis

Description: Embasaurus was named and described by Anatoly Riabinin in 1931. It is only known from two fragmentary vertebrae, which makes classification difficult. It has been classified as both a basal tyrannosauroid and a megalosaurid, depending on the analysis. Until more fossils are found, it will remain an indeterminate theropod.

7. “Bayosaurus”

Distribution: Cerro Lisandro Formation (Argentina)

Scientific Classification: Dinosauria, Saurischia, Theropoda, Ceratosauria, Abelisauroidea, Noasauridae?

Description: This small abelisauroid has yet to receive an official name. It was first described in a 2006 paper by Phil Currie, Rodolfo Coria, and Paulina Carabajal, who gave it the informal moniker of “Bayosaurus”. Known from a fragmentary postcranial skeleton, it has been estimated to have been around 4 meters (13 feet) long. There is a possibility that it could represent a noasaurid.

6. Thecocoelurus daviesi

Temporal Range: Barremian (129-125 Ma)

Distribution: Wessex Formation (England, United Kingdom)

Scientific Classification: Dinosauria, Saurischia, Theropoda, Tetanurae, Coelurosauria, Ornithomimosauria

Description: A single cervical vertebra was discovered on the Isle of Wight by Rev. William Fox sometime in the late 19th century. Harry Seeley referred it to Thecospondylus in 1888, while Franz Nopsca assigned it to Coelurus in 1901. In 1923, Friedrich von Huene decided that it was a distinct genus, and combined the previous names to form Thecocoelurus. In the past it has been classified as both an oviraptorosaur and therizinosaur, but is currently thought to be a basal ornithomimosaur.

5. Loncosaurus argentinus

Distribution: Cardiel Formation (Argentina)

Scientific Classification: Dinosauria, Ornithischia, Genasauria, Cerapoda, Ornithopoda incertae sedis

Description: Loncosaurus was the first dinosaur named from South America, being described by Florentino Ameghino in 1899. Known from a femur and tooth, it was originally thought to be a megalosaurid theropod. However, it was reassessed by Ralph Molnar in 1980; it turned out that the femur belonged to an ornithopod, while the tooth was from a theropod. The tooth was removed from the Loncosaurus holotype, and it is now classified as an indeterminate ornithopod.

4. Monkonosaurus lawulacus

Distribution: Lura Formation (Tibet, China)

Scientific Classification: Dinosauria, Ornithischia, Genasauria, Thyreophora, Stegosauria

Description: A pelvis, two vertebrae, and three plates are all the remains that are known from this stegosaur. It was named by Zhao Xijin in 1986, unfortunately without formal description. It wasn’t until 1990 when it was described by Dong Zhiming, meaning that the original name is technically invalid. Due to its obscurity, a replacement genus has never been suggested, and it is still referred to as Monkonosaurus.

3. “The Archbishop”

Temporal Range: Kimmeridgian-Tithonian (157-145 Ma)

Distribution: Tendaguru Beds (Tanzania)

Scientific Classification: Dinosauria, Saurischia, Sauropoda, Neosauropoda, Macronaria, Brachiosauridae

Description: In 1930, a large and partially complete skeleton of a brachiosaurid sauropod was discovered in the Tendaguru Beds by Frederick Migeod. Migeod assigned the specimen to Brachiosaurus brancai (now Giraffatitan), and it was mostly forgotten about for decades. It received the nickname “The Archbishop”, due to the shape of the vertebrae resembling an archbishop’s mitre. Then in 2005, Mike Taylor determined that “The Archbishop” was a brachiosaurid distinct from Brachiosaurus and Giraffatitan, and larger than both. The full description of the material by Taylor is due by the end of this year.

2. Kakuru kujani

Distribution: Marree Formation (Australia)

Scientific Classification: Dinosauria, Saurischia, Theropoda incertae sedis

Description: The tibia of this small theropod was discovered in 1973 in the Andamooka opal fields of Australia. As with many other fossils found there, the tibia had been completely mineralized into opal. Kakuru was described and named in 1980 by Ralph Molnar and Neville Pledge. It has been considered to be either a basal oviraptorosaur or a possible abelisauroid.

1. “Das Monster Von Minden”

Distribution: Unnamed formation (Germany)

Scientific Classification: Dinosauria, Saurischia, Theropoda, Megalosauroidea, Megalosauridae

Description: “Das Monster von Minden” (”The Monster of Minden”) is a megalosaurid that was discovered in 1999 near Minden, Germany. It is known from fragmentary cranial and postcranial fossils. It was recently described in a 2015 extract by Oliver Rauhut et al., where it was recovered as a sister taxon to both Megalosaurus and Torvosaurus. Estimates of its length have ranged from 8 meters (26 feet) all the way up to 15 meters (49 feet). There is a possibility that it could be the largest European theropod, if not one of the largest theropods as a whole.