''Anchisaurus'' is a genus of basal

sauropodomorph Sauropodomorpha ( ; from Greek, meaning "lizard-footed forms") is an extinct clade of long-necked, herbivorous, saurischian dinosaurs that includes the sauropods and their ancestral relatives. Sauropods generally grew to very large sizes, had lon ...

dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the evolution of dinosaurs is t ...

. It lived during the Early

Jurassic The Jurassic ( ) is a geologic period and stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately Mya. The Jurassic constitutes the middle period of ...

Period Period may refer to: Common uses * Era, a length or span of time * Full stop (or period), a punctuation mark Arts, entertainment, and media * Period (music), a concept in musical composition * Periodic sentence (or rhetorical period), a concept ...

, and its fossils have been found in the red sandstone of the

Portland Formation The Portland Formation is a geological formation in Connecticut and Massachusetts in the northeastern United States.Northeastern United States, which was deposited from the Hettangian age into the

Sinemurian In the geologic timescale, the Sinemurian is an age and stage in the Early or Lower Jurassic Epoch or Series. It spans the time between 199.3 ± 2 Ma and 190.8 ± 1.5 Ma (million years ago). The Sinemurian is preceded by the Hettangian and ...

age, between about 200 and 195 million years ago.Olsen, P.E. (2002)
STRATIGRAPHY AND AGE OF THE EARLY JURASSIC PORTLAND FORMATION OF CONNECTICUT AND MASSACHUSETTS: A CONTRIBUTION TO THE TIME SCALE OF THE EARLY JURASSIC
. Session No. 26 Studies of Depositional Systems and Sedimentary Rocks: In Honor of Edward Scudder Belt. 37th Annual Meeting (March 25–27, 2002). Until recently it was classed as a member of

Prosauropoda Plateosauria is a clade of sauropodomorph dinosaurs which lived during the Late Triassic to the Late Cretaceous. The name Plateosauria was first coined by Gustav Tornier in 1913. The name afterwards fell out of use until the 1980s. Classificati ...

. The

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

name ''Anchisaurus'' comes from the Greek ''αγχι'' (') ; "near, close" + Greek ('); "lizard". ''Anchisaurus'' was coined as a replacement name for "''Amphisaurus''", which was itself a replacement name for Hitchcock's "''Megadactylus''", both of which had already been used for other animals.

Discovery and naming

Sauropodomorph remains were first documented in North America in 1818, when some bones nearly in length were uncovered by Mr. Solomon Ellsworth Jr. while excavating a well with gunpowder in

East Windsor, Connecticut East Windsor is a town in Hartford County, Connecticut, United States. The population was 11,190 at the 2020 census. The town has five villages: Broad Brook, Melrose, Scantic, Warehouse Point and Windsorville. History In 1633, Settlers laid cl ...

. At the time of their discovery it was thought that the bones might be those of a human, but the presence of tail vertebrae falsified that idea. They are now recognized as those of an indeterminate sauropodomorph, possibly more closely related to the plateosaurian prosauropods. In 1855, the original

type specimen In biology, a type is a particular specimen (or in some cases a group of specimens) of an organism to which the scientific name of that organism is formally attached. In other words, a type is an example that serves to anchor or centralizes th ...

of ''Anchisaurus polyzelus'', AM 41/109, which is housed at the Amherst College Museum of Natural History, was found by William Smith in Springfield, Massachusetts during blasting a well for the waterhouse at the

Springfield Armory The Springfield Armory, more formally known as the United States Armory and Arsenal at Springfield located in the city of Springfield, Massachusetts, was the primary center for the manufacture of United States military firearms from 1777 until ...

. Unfortunately, both the East Windsor and Springfield specimens were severely damaged due to the blasting at the construction sites where they were found, and many of the bones were either accidentally thrown away by the workmen or kept by interested onlookers. As a result, these dinosaurs were only known from incomplete remains. In 1863, the son of the ichnologist Edward Hitchcock, Edward Hitchcock Jr, described the Springfield remains in a supplement to his father's work on fossil footprints, suggesting they could explain a certain mysterious kind of reptile tracks. He then contacted the British paleontologist Richard Owen. Owen advised him to name the finds as a new genus. Owen suggested the name ''Megadactylus'', "large finger" in Greek, in reference to the enormous thumb of the animal. Hitchcock Jr himself then chose the specific name ''polyzelus'', "much sought for" in Greek, referring to the fact that his father had for many years vainly sought to discover the identity of the track-maker. In 1877, Professor

Othniel Charles Marsh Othniel Charles Marsh (October 29, 1831 – March 18, 1899) was an American professor of Paleontology in Yale College and President of the National Academy of Sciences. He was one of the preeminent scientists in the field of paleontology. Among ...

had noted that the name ''Megadactylus'' had been preoccupied by ''Megadactylus'' Fitzinger 1843, a subgenus of the lizard genus '' Stellio''. In 1882, he replaced the name with ''Amphisaurus'', "near saurian", probably referring to Marsh's interpretation of it as intermediate between primitive dinosaurs—at the time the British ''

Palaeosaurus ''Palaeosaurus'' (or ''Paleosaurus'') is a genus of indeterminate archosaur known from two teeth found in the Bromsgrove Sandstone Formation and also either the Magnesian Conglomerate or the Avon Fissure Fill of Clifton, Bristol, England (ori ...

'' was an example of what was thought to be a primitive dinosaur—and more derived dinosaurs. In 1885, Marsh had discovered that this name also had been preoccupied, by the anthracosaurian ''Amphisaurus'' Barkas 1870, and again replaced it by ''Anchisaurus'', with the same meaning. Meanwhile, nearly complete specimens had been found in

Manchester, Connecticut Manchester is a town in Hartford County, Connecticut, United States. As of the 2020 United States Census, 2020 census, the town had a total population of 59,713. The urban center of the town is the Manchester (CDP), Connecticut, Manchester census- ...

. In 1884, a series of bridges was built over the Hop Creek.

Sandstone Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks. Most sandstone is composed of quartz or feldspar (both silicates ...

blocks were sawed out of Wolcott's Quarry north of

Buckland Station Buckland Station, a stagecoach station and hotel near Stagecoach, Nevada, was built c. 1870 by Samuel Buckland, proprietor (who settled here in 1859), replaced a previous stage station. It was built with simplified Greek Revival architecture, Gr ...

. On 20 October, an amateur paleontologist, Charles H. Owen, observed that a block had been removed containing the hind part of a skeleton. He warned Marsh who, using T. A. Bostwick as an intermediary, acquired the piece from the quarry owner, Charles O. Wolcott. Marsh tried to secure the front half of the skeleton but it had already been used in a bridge abutment. The specimen, YPM 208, was named ''Anchisaurus major'', "the larger one", by Marsh in 1889. Eventually, when the bridge was demolished in August 1969,

John Ostrom John Harold Ostrom (February 18, 1928 – July 16, 2005) was an American paleontologist who revolutionized modern understanding of dinosaurs in the 1960s. As first proposed by Thomas Henry Huxley in the 1860s, Ostrom showed that dinosaurs were ...

would save the front block. Subsequently, two other dinosaur fossils were located in the quarry. Six metres south of the original find a second skeleton was visible in the quarry face. It was removed as a single block and given the inventory number YPM 1883. In Yale, the part containing the skull was split off and became specimen YPM 40313. In 1891, Marsh made ''Anchisaurus major'' a separate genus, ''Ammosaurus'', the "sand saurian". In the same publication he named YPM 1883/YPM 40313 as a new species of ''Anchisaurus'', ''Anchisaurus colurus'', "the mangled one". They served as the templates from which O. C. Marsh in 1893 restored the skeleton. The Manchester specimens are now considered conspecific with ''Anchisaurus polyzelus''. The East Windsor and Manchester specimens are housed at the

Peabody Museum of Natural History The Peabody Museum of Natural History at Yale University is among the oldest, largest, and most prolific university natural history museums in the world. It was founded by the philanthropist George Peabody in 1866 at the behest of his nephew Oth ...

at Yale University. The

type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specime ...

is Hitchcock's ''A. polyzelus''. Marsh's ''A. major'' (also known as ''Ammosaurus''), ''A. solus'', and ''A. colurus'' (also known as ''Yaleosaurus''), have since been recognized as synonyms of ''A. polyzelus'', their supposed differences being due to misinterpretation and different stages of growth. In 2015, the ICZN formally made the more complete type specimen of ''A. colurus'' the

neotype In biology, a type is a particular specimen (or in some cases a group of specimens) of an organism to which the scientific name of that organism is formally attached. In other words, a type is an example that serves to anchor or centralizes the ...

of the genus ''Anchisaurus'' and the species ''A. polyzelus'', rendering ''A. polyzelus'' and ''A. colurus'' objective synonyms (both names being based on exactly the same fossil). Broom named '' Gyposaurus capensis'' in 1911, from bones discovered in South Africa but

Peter Galton Peter Malcolm Galton (born 14 March 1942 in London) is a British vertebrate paleontologist who has to date written or co-written about 190 papers in scientific journals or chapters in paleontology textbooks, especially on ornithischian and prosa ...

renamed these ''Anchisaurus capensis'' in 1976. This species has since been reclassified again and is probably a juvenile of ''

Massospondylus carinatus ''Massospondylus'' ( ; from Greek, (massōn, "longer") and (spondylos, "vertebra")) is a genus of sauropodomorph dinosaur from the Early Jurassic. (Hettangian to Pliensbachian ages, ca. 200–183 million years ago). It was described by Si ...

''. ''G. sinensis'' was also referred here, but appears to be a distinct animal. The

Navajo Sandstone The Navajo Sandstone is a geological formation in the Glen Canyon Group that is spread across the U.S. states of southern Nevada, northern Arizona, northwest Colorado, and Utah as part of the Colorado Plateau province of the United States.Anonymo ...

Arizona Arizona ( ; nv, Hoozdo Hahoodzo ; ood, Alĭ ṣonak ) is a state in the Southwestern United States. It is the 6th largest and the 14th most populous of the 50 states. Its capital and largest city is Phoenix. Arizona is part of the Fou ...

is the same age as the Portland Formation, and has produced

prosauropod Sauropodomorpha ( ; from Greek, meaning "lizard-footed forms") is an extinct clade of long-necked, herbivorous, saurischian dinosaurs that includes the sauropods and their ancestral relatives. Sauropods generally grew to very large sizes, had l ...

remains that have been referred to as ''Ammosaurus''.Galton, P.M. (1971). However, it is possible that these actually belong to the genus ''

Massospondylus ''Massospondylus'' ( ; from Greek, (massōn, "longer") and (spondylos, "vertebra")) is a genus of sauropodomorph dinosaur from the Early Jurassic. (Hettangian to Pliensbachian ages, ca. 200–183 million years ago). It was described by S ...

'', otherwise known only from South Africa.Galton, P. M., Upchurch, P. (2004). In the eastern Canadian province of

Nova Scotia Nova Scotia ( ; ; ) is one of the thirteen provinces and territories of Canada. It is one of the three Maritime provinces and one of the four Atlantic provinces. Nova Scotia is Latin for "New Scotland". Most of the population are native Eng ...

, scientists have unearthed prosauropods from the

McCoy Brook Formation The McCoy Brook Formation is a geological formation dating to roughly between 200 and 190 million years ago and covering the Hettangian to Sinemurian stages. The McCoy Brook Formation is found in outcrops around the Bay of Fundy, Nova Scotia. ...

, which is about 200 to 197 million years old, from the Early Jurassic Hettangian stage. The Nova Scotia material provides clues about the diet of these animals. A large number of

gastrolith A gastrolith, also called a stomach stone or gizzard stone, is a rock held inside a gastrointestinal tract. Gastroliths in some species are retained in the muscular gizzard and used to grind food in animals lacking suitable grinding teeth. In oth ...

s, stones swallowed to grind up plant material in the gut, were found in the abdomen, as well as bone from the skull of a small

sphenodont Rhynchocephalia (; ) is an order of lizard-like reptiles that includes only one living species, the tuatara (''Sphenodon punctatus'') of New Zealand. Despite its current lack of diversity, during the Mesozoic rhynchocephalians were a diverse gro ...

, ''

Clevosaurus ''Clevosaurus'' (meaning "Gloucester lizard") is an extinct genus of rhynchocephalian reptile from the Triassic, Late Triassic and the Jurassic, Early Jurassic Period (geology), periods. Species of ''Clevosaurus'' were widespread across Pangaea, ...

''. This indicates that these dinosaurs were omnivorous, with a diet mainly consisting of plants but with an occasional supplement of meat.Shubin, N. H. ''et al.'' (1994). However, these remains have never been fully described or illustrated and were only tentatively referred to ''Ammosaurus''. A further study identified them as a new taxon of sauropodomorph, '' Fendusaurus eldoni''.Fedak, T. J. (2007).

Description

''Anchisaurus'' was a rather small dinosaur, with a length of just over , which helps explain why it was once mistaken for human bones."Anchisaurus." In: Dodson, Peter & Britt, Brooks & Carpenter, Kenneth & Forster, Catherine A. & Gillette, David D. & Norell, Mark A. & Olshevsky, George & Parrish, J. Michael & Weishampel, David B. ''The Age of Dinosaurs''. Publications International, LTD. p. 27. . It probably weighed around . However, Marsh's species ''A. major'' (also known as ''Ammosaurus'') was larger, from and some estimates give it a weight of up to .

Gregory S. Paul Gregory Scott Paul (born December 24, 1954) is an American freelance researcher, author and illustrator who works in paleontology, and more recently has examined sociology and theology. He is best known for his work and research on theropod dino ...

estimated its length at and its weight at in 2010.Paul, G.S., 2010, ''The Princeton Field Guide to Dinosaurs'', Princeton University Press p. 163 According to the presence of cf. ''

Otozoum ''Otozoum'' ("giant animal") is an extinct ichnospecies of fossilized sauropodomorph dinosaur footprints and other markings in sandstones. They were made by heavy, bipedal animals (probably dinosaurs) with a short stride that walked on four toes ...

'' tracks on the Connecticut Valley, ''Anchisaurus'' could reach even greater sizes. ''Otozoum'' tracks were made by a semibipedal to quadrupedal sauropodomorph close to or on the line leading toward eusauropods. ''Anchisaurus'' is one of the two sauropodomorphs recognized in the zone. Based on the four known specimens of ''Anchisaurus'', Yates estimated that the animal measured up to in length. This matches well with the estimated average size of the adult ''Eubrontes'' track-maker in the Hartford and Deerfield basins. Based on the largest known ''Eubrontes'' footprint, exceptionally large individuals of ''Anchisaurus'' probably measured up to in length.

Classification

Due to its primitive appearance, ''Anchisaurus'' was previously classified as a prosauropod, a member of a group of animals related to or ancestral to the sauropods. Recent investigations show that a group of traditional prosauropods form a monophyletic sister-group to Sauropoda, and that ''Anchisaurus'' is instead closer to sauropods. The family Anchisauridae was first proposed by

in 1885 and later defined as a clade consisting of ''Anchisaurus'' and its nearest relatives. However, it is not clear which other genera are included in the family; many of the dinosaurs once included have since been moved elsewhere, and the group is not used in most current taxonomies.

Paleobiology

Fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

s of ''Anchisaurus'' were originally discovered in the

Portland Formation The Portland Formation is a geological formation in Connecticut and Massachusetts in the northeastern United States.Newark Supergroup The Newark Supergroup, also known as the Newark Group, is an assemblage of Upper Triassic and Lower Jurassic sedimentary rocks which outcrop intermittently along the United States East Coast. They were deposited in a series of Triassic basins ap ...

in the Connecticut River Valley. This formation preserves an arid environment with strong wet and dry seasons, from the Hettangian age into the

age, between about 200 and 195 million years ago. Digesting plant matter is a much more intensive biochemical process than digesting meat. This herbivore swallowed

gastroliths A gastrolith, also called a stomach stone or gizzard stone, is a rock held inside a gastrointestinal tract. Gastroliths in some species are retained in the muscular gizzard and used to grind food in animals lacking suitable grinding teeth. In oth ...

(gizzard stones) to help break down the food in its stomach. Herbivorous dinosaurs needed a huge gut. Since this had to be positioned in front of the pelvis, balancing on two legs became increasingly difficult, as dinosaurs became larger and they gradually evolved into the

quadruped Quadrupedalism is a form of locomotion where four limbs are used to bear weight and move around. An animal or machine that usually maintains a four-legged posture and moves using all four limbs is said to be a quadruped (from Latin ''quattuor' ...

al position that characterizes the later sauropods such as ''

Diplodocus ''Diplodocus'' (, , or ) was a genus of diplodocid sauropod dinosaurs, whose fossils were first discovered in 1877 by S. W. Williston. The generic name, coined by Othniel Charles Marsh in 1878, is a neo-Latin term derived from Greek δι� ...

''. Prosauropods represented a middle phase between the earliest bipedal herbivores and the later giant sauropods. As a prosauropod, ''Anchisaurus'' was mostly typical of this group, which flourished briefly during the late

Triassic The Triassic ( ) is a geologic period and system (stratigraphy), system which spans 50.6 million years from the end of the Permian Period 251.902 million years ago (Year#Abbreviations yr and ya, Mya), to the beginning of the Jurassic Period 201.36 ...

and early Jurassic. ''Anchisaurus'' teeth, used to rip food, were shaped like spoons. It had fewer and more widely spaced teeth than true prosauropods, and as Peter Galton and Michael Cluver observed, narrower feet. ''Anchisaurus'' would have spent most of its time on four legs but could have reared up on its hind legs to reach higher plants. As a

facultative biped A facultative biped is an animal that is capable of walking or running on two legs (bipedal), as a response to exceptional circumstances (facultative), while normally walking or running on four limbs or more. In contrast, obligate bipedalism is w ...

, ''Anchisaurus'' had to have multi-purpose front legs. As 'hands', they could be turned inwards and be used for grasping. It had a simple reversible first 'finger', similar to a 'thumb'. As feet, the five toes could be placed flat against the floor and were strong at the ankle. This unspecialized design is typical of the early dinosaurs.

References

{{Taxonbar, from=Q311281 Early Jurassic dinosaurs of North America Anchisauria Fossil taxa described in 1885 Taxa named by Othniel Charles Marsh Paleontology in Connecticut