New England\'s trackways of Connecticut River Valley by Fred Bervoets
by Fred Bervoets
For more than 160 years the Connecticut River Valley is famous for its valuable resource of vertebrate and invertabrate traces. The Connecticut River Valley is known as one of the world\'s richest grounds for unearthing dinosaur tracks. Some 200 million years ago, conditions in the valley were ripe for creating fossilized prints. And as early as 1802, footprints were being found in rock nearby South Hadley.
In 1802, Pliny Moody was plowing his father\'s field in South Hadley when he unearthed a slab of reddish rock bearing several small three-toed footprints embedded in it. He dug up the slab and used it as a door step, on exhibit to anyone who entered the Moody household. A local doctor decided they must be prints that were possibly as old as the Great Flood. Calling them the tracks of \"Noah\'s Raven\".
Later in 1835 Greenfield sidwalks were being paved with flat shale from a Turner\'s Falls quarry. As it went down, residents remarked at the curious \"turkey tracks\" in the rock. A local doctor, sensing the tracks\' significance, contacted a professor at Amherst College, Edward Hitchcock, and asked him to come to Greenfield to take a look.
That began 30 years of work by Hitchcock in the quarries in Turners Falls, Granby, Gill and other areas, cracking rocks to find their fossilized treasures. His work made the Connecticut Valley famous amoung paleontologists and others interested in dinosaurs. Hitchcock systematically excavated, described, and classified thousands of tracks in remarkable detail, culminating in a monumental volume (Hitchcock, 1858), which is still a classic reference work in the field.
Hitchcock (1793-1864) who is considered the father of vertebrate ichnology was so the first who scientifically studied en described these dinosaur tracks in 1836 a time before dinosaurs were even known.
[Hitchcock, E. (1836) Ornithichi chnology. Description of the footmarks of birds (ornithichnites) of New Red Sandstone in Massachusetts. Am. J. Sci. 29, 307-340]
His collections are now held in the Pratt Museum of Amherst College, Massachusetts which contains the largest dinosaur footprint collection in the world, largely amassed by Edward Hitchcock who first stored the footprints in the special build Appleton Cabinet. Other works of Hitchcock about the New England fossiltracks are:
[Hitchcock, E. (1848). An attempt to discriminate and describe the animals that made the fossil footmarks of the United States, and especially of New Fngland. Mem. Am. Acad. Arts Sci. 3:129-256.]
[Hitchcock, E. (1858) Ichnology of New England: A report of the Sandstone of the Connecticut Valley, Especially Its Fossil Footmarks, pp. 232, White Boston. [Reprinted by Arno Press; in the Natural Sciences in America Series]
[Hitchcock, E. (1865). A supplement to the ichnology of New England. Wright and Porter, Boston. 96 pp.]
Despite the fact that the term dinosaur had not even been coined at that time, Hitchcock noted that the huge footprints he saw had a mysteriously bird-like quality, an insight that now seems prophetic. During his life he attributed more work to birds and dondinosaurian reptiles than to dinosaurs.
In the 19th century the conditions in the Connecticut Valley were ideal for fossil collection, thats why most trackways from this area are discovered during that time. The Turner Falls Sandstone and the Portland Formation are the sediments in which many of the footprints were discovered. During the middle of the 1800\'s many farms in New England were abandoned and forrest\'s reclaimed that area\'s, besides that dams were build at several points along the river.
The result is that many trackways are overgrown by forrest or are submerged and often only accesible by boat. Hitchcock had assigned genus and species names for the tracks in the Linnean binomial system and changed these names as his perceptions of the trackmakers changed and he allmost never acknowledged previous names in subsequent publications. Richard Swan Lull attempted to sort out the morass of ichnogenera and ichnospecies names that were Hitchcock\'s legacy.
[Lull, R.S. (1904). Fossil footprints of the Jura-Trias of North America. Mem. Boston Soc. Nat. History 5, 461-557]
Unfortunately his nomenclatural work only made the confusion bigger, when he resurrect old and abandoned names. Another work of Lull about Connecticut Valley is:
[Lull, R.S. (1953). Triassic life of the Connecticut Valley. State Geological and Natural History Survey of Connecticut Bull. 81 pp. 336].
Olson and co-workers (1986; 1992) also attempted to revise some of the tangled nomenclature.
[Olsen, P.E. and Baird, D. (1986). The ichnogenus Atreipus and its significance for Triassic biostratigraphy. In The Beginning of the Age of Dinosaurs: Faunal Change across the Triassic-Jurassic Boundary (K. Padian, Ed), pp. 61-87. Cambridge Univ. Press. Cambridge, UK]
[Olsen, P.E., McDonald, N.G., Huber, P. and Cornet, B. (1992). Stratigraphy and paleoecology of the Deerfield Rift Basin (Triassic-Jurassic, Newark Supergroup), Massachusetts. In Guidebook for Field Trips in the Connecticut Valley region of Massachusetts and Adjacent Scales. (P. Robinson and J.B. Brady, Eds.), Vol.2 pp. 488-535.]
They demonstrated that if the lengths of the ichnogenera Grallator, Anchisauripus and Eubrontes which represent small, medium and large theropods respectively are plotted against their widths, all three types show a complete graduation in size and proportions and their species frequently overlap. Other known tracks belong to a small ornithopod named Anomoepus, the small crocodilomorph Batrachopus probably an insectivore/carnivore dinosaur and the basal thyreophoran Otozoum. There are also tracks that seem to have been produced by juvenile theropods. The Early Jurassic rocks near Mt. Tom, Massachusetts consists of numerous nearparallel Eubrontes tracks which have long been interpreted as a flock or herd (Hitchcock, 1848, 1858; Ostrom 1972, 1986) Eubrontes prints are generally regarded as pertaining to a theropod, although they have also been called herbivore tracks.
The trackways at Mt. Tom are arrayed in side-by-side fashion with little overstepping, un unexpected pattern for a herd. Ripple marks indicate a downslope direction approximately perpendicular to the preferred orientation of the trackways. About 86% of the trackways are going in the same direction (Ostrom, 1972; 1986) In the Connecticut Valley from Connecticut and Massachusetts, the track- bearing strata are contained in the rift basins and are called the Hartford and Deerfield basins. The sediments of this basins occur over more than 160 km and contain over 4000 meter of predominatly red, grey, and black clastic sediments and tholeiitic basalt which was deposited over an period of approximately 35 million year during the Late Triassic and Early Jurassic. The Connecticut River Valley tracks however are only Early Jurassic.
The Connecticut Valley is a part of the so called Newark Supergroup which comprises several thousand meters of Triassic fluvial and lacustrine sedimentary rocks as well as Jurassic sedimentary deposits interbedded with flows of basalt lavas. These starta were deposited in 13 or so major rift basins that developed during the breakup of Pangaea and the start of the opening of the Atlantic Ocean in the Middle Jurassic. It is likely that the climate throughout this period was mostly subtropical, monsoonal characterized by alternating episodes of high precipiation and airdity.
Connecticut Valley shows a very rare faunal distribution pattern, one-third of the fauna is composed of theropods, 15% consist of invertebrates and only 11% is made up of herbivores, an very unsustainable ecological situation.
The Connecticut River Valley has proven to be a verry valuable resource, besides the vertebrate and invertebrate foss ils plantfossils also occur in this rich sediments. One of the latest discoveries of a trackway in New England was made on March 25, 1996 by a local landowner in Holyoke who discovered a 200 million-year-old trackway site on his property just a few miles away at the farm of Pliney Moody.
The first prints that were found on this new Holyoke site were a little over four feet down in a bedrock outcropping. Upon clocer examination of the site,track-bearing layers were found well above the first find. It proved to be a unique trackway sandwich!
Psihoyos, L. (1997) History of dinosaur discoveries IV Research today (in Encyclopedia of Dinosaurs (Currie, P.J. and Padian, K. eds) pp.352-355
Wright.J. (1997) Connecticut River Valley (in Encyclopedia of Dinosaurs (Currie, P.J. and Padian, K. eds) pp.143-146
Lockley, M. (1997) Footprints and Trackways (in Encyclopedia of Dinosaurs (Currie, P.J. and Padian, K. eds) pp.242-245
Sues, H.-D., (1997) Newark Supergroup (in Encyclopedia of Dinosaurs (Currie, P.J. and Padian, K. eds) pp.479-480
Coombs, W.J. jr. (1990) Dinosaur Relationships, Biology, Distibutions Part I Behaviour patterns of Dinosaurs / Structuerd ichnocoenoses in The Dinosauria (Weishampel, Dodson and Osmolska eds) Univ. of California Press. p. 35.
Special thanks to Emma C. Rainforth