tracks

Fossil samples – e.g. ‘primitive’ bony fish (1, 2), a skull of a temnospondyl ‘amphibian’ (probably a metoposauroid) in dorsal view (3), a skull of an archosaur of the crocodile lineage (probably a phytosaur) in palatal view (4), holotype of the “gliding reptile” Icarosaurus siefkeri [1] (5) and Atreipus-Grallator-type dinosaur tracks (bottom right) – from the Newark Supergroup, i.e. a series of mainly Late Triassic to Early Jurassic sedimentary rocks of eastern North America ↑ Edwin H. Colbert: A gliding reptile from the Triassic of New Jersey. American Museum Novitates, 2230. American Museum of Natural History, New York 1966, digitallibrary.amnh.org, cf. fig. 3 therein.

A, Photograph of the D. rarus holotype; B, Diagram of the D. rarus holotype; C, Diagram of the D. rarus holotype (left) and paratype (right); D, Photograph of the seven individual tracks of the D. rarus holotype

Original figure caption: .mw-parser-output .smallcaps{font-variant:small-caps}The Middletown Slab covered with the Footprints of Carnivorous Dinosaurs. The tracks are in high relief. Additional notes: Most if not all of these tridactylous (i.e. three-toed) footprints/tracks (but not the actual trackmaker!) are referred to as Grallator or as Grallator-type trace fossils. “High relief” means that these are actually casts of footprints forming a positive relief on the lower surface of the sandstone slab (so-called positive hyporelief). The material that originally formed the mud over which the dinosaurs walked was too friable to be recovered from the quarry in one piece. The slab consists of so called ‘brownstone’ which is the trading name of the sandstone quarried at Middletown, Connecticut. This sandstone belongs to the Lower Jurassic Portland Formation of the Hartford Basin (“Connecticut Valley”) and thus to the upper part of the Newark Supergroup. The trackmakers probably were relatively small ‘primitive’ theropod dinosaurs (coelophysoids) such as Podokesaurus the remains of which were recovered from Lower Jurassic deposits of the Hartford Basin.

Eubrontes dinosaur track from the Jurassic of Connecticut, USA. Trace fossils are any indirect evidence of ancient life. They refer to features in rocks that do not represent parts of the body of a once-living organism. Traces include footprints, tracks, trails, burrows, borings, and bitemarks. Body fossils provide information about the morphology of ancient organisms, while trace fossils provide information about the behavior of ancient life forms. Interpreting trace fossils and determination of the identity of a trace maker can be straightforward (for example, a dinosaur footprint represents walking behavior) or not. Sediments that have trace fossils are said to be bioturbated. Burrowed textures in sedimentary rocks are referred to as bioturbation. Trace fossils have scientific names assigned to them, in the same style & manner as living organisms or body fossils. This track was made by a theropod, a group of small to large, carnivorous, bipedal dinosaurs. The specimen comes from a Triassic to Jurassic terrestrial sedimentary succession that filled up a half graben, many of which occur along America's eastern seaboard. Such half-graben basins formed during the Triassic as the Pangaea supercontinent tried to rift apart, but failed. Pangaea successfully broke apart during the Jurassic. Stratigraphy: East Berlin Formation, Newark Supergroup, Lower Jurassic Locality: unrecorded / undisclosed site at or near the town of Rocky Hill, central Connecticut, USA Info. at: mrdata.usgs.gov/geology/state/sgmc-unit.php?unit=CTJeb%3B0 and en.wikipedia.org/wiki/Eubrontes

Wide angle photo from the visitor’s walkway inside Lark Quarry Dinosaur Trackways, Australia. Here, the camera is pointing towards the south west corner of the building. On the top (in the far corner) is the natural landscape. In the middle ground of the photo, some of the overburden has been cleared. In the foreground is the dinosaur tracks.

Original figure caption: Trackway S1 (Eosauropus sp.), here attributed to a sauropod trackmaker based on pedal synapomorphies; trackmaker is moving towards the south-west. Two consequtive pes impressions of a tridactyl Grallator [i.e. a theropod] trackway can be seen left to the S1 trackway. Note: The tracks are preserved on a bedding plane of a thin siltstone bed of the Late Triassic Fleming Fjord Formation of East Greenland. A) shows a photograph of the trackway(s) as preserved on the bedding plane (i.e. as concave epireliefs); B) shows a color shaded relief map based on a high-resolution photogrammetric 3D-model of the bedding plane; C) is an interpretative outline drawing of the S1 trackway; abbreviations: LM = left manus (i.e. forefoot), LP = left pes (i.e. hindfoot), RM = right manus, RP = right pes, numbers increase in walking direction.

A short hike leads past an interpretive sign to a set of Megalosauripus tracks set down 160 million years ago within Bears Ears National Monument. Photos by Bob Wick - BLM

A short hike leads past an interpretive sign to a set of Megalosauripus tracks set down 160 million years ago within Bears Ears National Monument Photos by Bob Wick - BLM

A, Four consecutive track casts of Minisauripus isp.; B, Natural impression slab of second left and right feet tracks; C, Isolated fifth track of Minisauripus isp.

Tracks of the dinosaur Pseudotetrasauropus bipedoida.

In 2000 a virtually complete Scelidosaurus skeleton was discovered in England. This fossil's hundreds of armor plates and spikes are preserved in their life positions, providing extraordinary details about how this dinosaur looked. St. George is the only place anywhere in the Western Hemisphere that the 11-foot long Scelidosaurus replica has been on display. The St. George Dinosaur Discovery Site at Johnson Farm (St. George, Utah) is home to exceptionally well-preserved dinosaur tracks, some displaying skin impressions. These tracks, along with hundreds of fossil fish, plants, rare dinosaur remains, invertebrates traces and important sedimentary structures, show evidence that this site was produced along the western edge of a large, Early Jurassic (age between 195-198 million years ago) freshwater lake named Lake Dixie. Source: www.sgcity.org/dinotrax/

In 2000 a virtually complete Scelidosaurus skeleton was discovered in England. This fossil's hundreds of armor plates and spikes are preserved in their life positions, providing extraordinary details about how this dinosaur looked. St. George is the only place anywhere in the Western Hemisphere that the 11-foot long Scelidosaurus replica has been on display. The St. George Dinosaur Discovery Site at Johnson Farm (St. George, Utah) is home to exceptionally well-preserved dinosaur tracks, some displaying skin impressions. These tracks, along with hundreds of fossil fish, plants, rare dinosaur remains, invertebrates traces and important sedimentary structures, show evidence that this site was produced along the western edge of a large, Early Jurassic (age between 195-198 million years ago) freshwater lake named Lake Dixie. Source: www.sgcity.org/dinotrax/

Magnoavipes sp. - dinosaur track from the Cretaceous of Colorado, USA. (replica; public display, Red Rocks Amphitheater visitor center, west of Denver, Colorado, USA) Dinosaur Ridge, Colorado has numerous dinosaur fossils, including bones and tracks. The most common track type at the site is Caririchnium leonardii, which was made by an iguanodontid dinosaur. A less common track is this - a slender, three-toed print called Magnoavipes, which was made by a theropod dinosaur. Stratigraphy: Dakota Sandstone, upper Lower Cretaceous Provenance: eastern side of Dinosaur Ridge, Dakota Hogback, west of Denver, north-central Colorado, USA

Otozoum tracks in the Dinosaur State Park and Arboretum, Rocky Hill, Connecticut, USA. The exhibit sign reads: "These large negative tracks were made by a heavy animal that walked on four toes and had a short stride. It may have been a prosauropod. All of these tracks have rare skin impressions. This specimen was removed from the Portland Quarry in 1896. Donated by Wesleyan University."

Morphological variation in the Deltapodus ibericus holotype trackway from the CT-1 tracksite. (a) False-color depth maps and interpretative outline drawings of a selection of manus–pes sets within the trackway. Note the variation in manus (from crescent, kidney to semicircular shapes) and pes (reversed delta, semirectangular, and oval shapes) tracks depending on the manus–pes set. Note also that some manus are overprinted by the pes. (b) Mediotype of the pes impressions based on 4 specimens with a mean footprint length of 0.48 m. Note that the morphology of the posterior part of the print is slightly biased (more quadrangular) because this area in track 1CA17p is broken. (c) Mediotype of the manus impressions based on 2 specimens with a mean footprint width of 0.37 m. (d–f) Pictures of a selection of the best-preserved tracks (manus–pes set 1CA23, pes 1CA17p and manus 1CA3m). The false color depth maps were generated with the software CloudCompare (https://www.cloudcompare.org/) and the mediotypes with the software DigTrace (https://www.digtrace.co.uk/).

Caririchnium leonardii - dinosaur track from the Cretaceous of Colorado, USA. (replica; public display, Red Rocks Amphitheater visitor center, west of Denver, Colorado, USA) Dinosaur Ridge, Colorado has numerous dinosaur fossils, including bones and tracks. The most common track type at the site is Caririchnium leonardii, which was made by an iguanodontid dinosaur. The large, wide, three-toed print was produced by a hindfoot. Stratigraphy: Dakota Sandstone, upper Lower Cretaceous Provenance: eastern side of Dinosaur Ridge, Dakota Hogback, west of Denver, north-central Colorado, USA