Question: What is the species type of this early herbivorous dinosaur that was the subject of a paper written by Matt J. Wedel?
Context: "Yibinosaurus" (meaning "Yibin lizard") is the informal name given to an as yet undescribed genus of herbivorous dinosaur from the Early Jurassic.  It was a sauropod which lived in what is now Sichuan, China.  The suggested "type species", "Yibinosaurus zhoui", has not been formally described yet, but the formal publication is forthcoming, from Chinese paleontologist Ouyang Hui.  "Yibinosaurus" was only briefly mentioned in the Chongqing Natural History Museum guidebook (2001) and is thus a "nomen nudum". Samuel Husbands Beckles (12 April 1814 in Barbados – 4 September 1890 in Hastings) was a Bajan/English 19th-century lawyer, turned dinosaur hunter, who collected remains in Sussex and the Isle of Wight.  In 1854 he described bird-like trackways that he thought could have been made by dinosaurs, which he later identified as probably those of "Iguanodon" in 1862.  In 1857, following the discovery of a mammal jaw at Durlston Bay, he directed a major excavation that became known as 'Beckles' Pit', removing five metres of overburden over a 600 square metre area, one of the largest ever scientific excavations.  The collection of mammal fossils that resulted is now mainly held at the Natural History Museum.  He discovered the small herbivorous dinosaur "Echinodon".  The only known species "Echinodon becklesii", the mammal "Plagiaulax becklesii" and the dinosaur "Becklespinax" were named in his honour. Lambeosaurus ( ; meaning "Lambe's lizard") is a genus of hadrosaurid dinosaur that lived about 75 million years ago, in the Late Cretaceous period (Campanian) of North America.  This bipedal/quadrupedal, herbivorous dinosaur is known for its distinctive hollow cranial crest, which in the best-known species resembled a hatchet.  Several possible species have been named, from Canada, the United States, and Mexico, but only the two Canadian species are currently recognized as valid. Parksosaurus (meaning "William Parks's lizard") is a genus of hypsilophodont ornithopod dinosaur from the early Maastrichtian-age Upper Cretaceous Horseshoe Canyon Formation of Alberta, Canada.  It is based on most of a partially articulated skeleton and partial skull, showing it to have been a small, bipedal, herbivorous dinosaur.  It is one of the few described non-hadrosaurid ornithopods from the end of the Cretaceous in North America, existing around 70 million years ago. Nopcsaspondylus (meaning "Franz Nopcsa's vertebra", in reference to the original describer) is a genus of rebbachisaurid sauropod dinosaur (a type of large, long-necked quadrupedal herbivorous dinosaur) from the Cenomanian-age (Upper Cretaceous) Candeleros Formation of Neuquén, Argentina.  It is based on a now-lost back vertebra described by Nopcsa in 1902 but not named at the time.  The specimen had a small vertebral body and large hollows, now known to be typical of rebbachisaurids. Aquilops is an early herbivorous ceratopsian dinosaur dating from the Early Cretaceous of North America, approximately 108 million to 104 million years ago.  The type species is A. americanus. Amargatitanis (meaning "Amarga giant") is a genus of dicraeosaurid sauropod dinosaur (a type of large, long-necked quadrupedal herbivorous dinosaur) from the Barremian-age (Lower Cretaceous) La Amarga Formation of Neuquén, Argentina. Iguanodontia (or iguanodonts) is a clade of herbivorous dinosaurs that lived from the Middle Jurassic to Late Cretaceous.  Some members include "Camptosaurus", "Callovosaurus", "Iguanodon", "Tenontosaurus", and the hadrosaurids or "duck-billed dinosaurs".  Iguanodontians were one of the first groups of dinosaurs to be found.  They are among the best known of the dinosaurs, and were among the most diverse and widespread herbivorous dinosaur groups of the Cretaceous period.  Derived iguanodontians (such as "Muttaburrasaurus" and many ankylopollexians) were generally large animals, and some (such as "Shantungosaurus", which measured up to 50 ft (15 m) in length and weighed up to 8 tons) equaled the largest carnivorous dinosaurs in size. Michael P. Taylor (born March 12, 1968) is a British computer programmer with a Ph.D in palaeontology.  To date, he has published 18 paleontological papers and is co-credited with naming three genera of dinosaur ("Xenoposeidon" in 2007 with Darren Naish, "Brontomerus" in 2011 with Matt J. Wedel and Richard Cifeli, and "Haestasaurus" in 2015 with Paul Upchurch and Phil Mannion). Mathew John Wedel is an American paleontologist.  He is associate professor at the Western University of Health Sciences Department of Anatomy in California.  Mathew studies sauropods and the evolution of pneumatic bones in dinosaurs.  At Western University, Mathew teaches gross anatomy.  He has authored papers naming "Aquilops" (2014), "Brontomerus" (2011), and "Sauroposeidon" (2000).
Answer: A. americanus