1998Journal of Vertebrate PaleontologyRequires access

Type material of the type species of the classic theropod footprint genera Eubrontes, Anchisauripus , and Grallator (Early Jurassic, Hartford and Deerfield basins, Connecticut and Massachusetts, U.S.A.)

Paul E. Olsen, Joshua B. Smith, Nicholas G. McDonald

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Abstract

The classic Early Jurassic age theropod footprints Eubrontes giganteus, Anchisauripus sillimani, and Grallator parallelus were established by Edward Hitchcock in 1836–1847 and are the type ichnospecies of their respective ichnogenera. We identify, describe, and figure the type specimens in detail for the first time since they were named. We also figure and describe the other elements of the type series as well as specimens mistakenly thought to be the types. All of the tracks come from cyclical lacustrine and marginal lacustrine to fluvial strata from an interval spanning about one million years in the Early Jurassic age Meriden and Agawam groups of the Hartford and Deerfield basins of Connecticut and Massachusetts. Based on osteometric comparisons with skeletal material, these three ichnospecies were most likely made by theropod dinosaurs, as usually assumed. Although treated here as distinct ichnogenera, it is possible that their major proportional differences derive from allometric growth with individuals of several related species in one genus or even within one species of trackmaker. The rigorous establishment of these classic ichnological taxa forms a basis for more wide ranging studies of theropod diversity in the early Mesozoic.

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The classic Early Jurassic age theropod footprints Eubrontes giganteus, Anchisauripus sillimani, and Grallator parallelus were established by Edward Hitchcock in 1836–1847 and are the type ichnospecies of their respective ichnogenera. We identify, describe, and figure the type specimens in detail for the first time since they were named. We also figure and describe the other elements of the type series as well as specimens mistakenly thought to be the types. All of the tracks come from cyclical lacustrine and marginal lacustrine to fluvial strata from an interval spanning about one million years in the Early Jurassic age Meriden and Agawam groups of the Hartford and Deerfield basins of Connecticut and Massachusetts. Based on osteometric comparisons with skeletal material, these three ichnospecies were most likely made by theropod dinosaurs, as usually assumed. Although treated here as distinct ichnogenera, it is possible that their major proportional differences derive from allometric growth with individuals of several related species in one genus or even within one species of trackmaker. The rigorous establishment of these classic ichnological taxa forms a basis for more wide ranging studies of theropod diversity in the early Mesozoic.

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Available abstract

The classic Early Jurassic age theropod footprints Eubrontes giganteus, Anchisauripus sillimani, and Grallator parallelus were established by Edward Hitchcock in 1836–1847 and are the type ichnospecies of their respective ichnogenera. We identify, describe, and figure the type specimens in detail for the first time since they were named. We also figure and describe the other elements of the type series as well as specimens mistakenly thought to be the types. All of the tracks come from cyclical lacustrine and marginal lacustrine to fluvial strata from an interval spanning about one million years in the Early Jurassic age Meriden and Agawam groups of the Hartford and Deerfield basins of Connecticut and Massachusetts. Based on osteometric comparisons with skeletal material, these three ichnospecies were most likely made by theropod dinosaurs, as usually assumed. Although treated here as distinct ichnogenera, it is possible that their major proportional differences derive from allometric growth with individuals of several related species in one genus or even within one species of trackmaker. The rigorous establishment of these classic ichnological taxa forms a basis for more wide ranging studies of theropod diversity in the early Mesozoic.

Key concepts: Paleontology, Type (biology), Geology, Taxon, Mesozoic, Genus, Footprint, Fluvial

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Type material of the type species of the classic theropod footprint genera Eubrontes, Anchisauripus , and Grallator (Early Jurassic, Hartford and Deerfield basins, Connecticut and Massachusetts, U.S.A.) — Research Paper | ScholarLens