Also known as Hotton locality; Dinosaur Park, M-NCPPC, Washington Brick Company; Muirkirk

Where: Prince George's County, Maryland (39.1° N, 76.9° W: paleocoordinates 32.9° N, 31.3° W)

• coordinate stated in text

• outcrop-level geographic resolution

When: Arundel Clay Formation (Potomac Group), Late/Upper Aptian (122.5 - 113.0 Ma)

• Palynology of the Potomac Group suggests a late Aptian age for the Arundel facies (Brenner, 1963; Doyle and Robbins, 1977; Hochuli et al., 2006; Doyle, 2012)

•Arundel Clay facies of the Patuxent Formation (Aptian, Lower Cretaceous).

• group of beds-level stratigraphic resolution

Environment/lithology: wet floodplain; concretionary, gray, carbonaceous claystone and brown, red claystone

Size classes: macrofossils, mesofossils, microfossils

• The fossil-yielding zone at the site is reasonably productive insofar as fragmentary bones and teeth of large vertebrates are concerned

Collected by Kranz, Lipka, Cifelli in 1980s–present; reposited in the UNSM

Collection methods: bulk, quarrying, surface (float), surface (in situ), sieve,

• A sustained field program by one of us (T.R.L.) resulted in the recovery of many new fossils from a single site in the Arundel Clay. The site, formerly mined commercially for clay, is now known as Dinosaur Park, managed by the Prince George’s County Department of Parks and Recreation. Previously described fossils from the site, USNM locality 41614, were obtained by surface prospecting (Lipka 1998; Cifelli et al. 1999; Rose et al. 2001; Lipka et al. 2006) and include those of the triconodontid mammal Arundelconodon hottoni Cifelli et al., 1999. The specimen described herein is the single mammalian fossil obtained through screenwashing and associated concentration techniques, aimed at recovery of vertebrate microfossils. The fossil-yielding zone at the site is reasonably productive insofar as fragmentary bones and teeth of large vertebrates are concerned. Informative microfossils are abundant at USNM locality 41614 (T.R.L. and R.L.C., work in progress). However, processing of washed concentrate is impeded considerably by the fact that the rock also happens to be a prolific source of concretions, carbonized wood, and other unwanted residues. Rock matrix was reduced through a two-phase screenwashing process (standard water wash followed by kerosene displacement method); further concentrated using the heavy liquid ZnBr2; and picked under a binocular dissecting microscope, using established procedures (see Cifelli et al. 1996 and references therein).

Primary reference: G. J. Brenner. 1963. The spores and pollen of the Potomac Group of Maryland. State of Maryland Board of Natural Resources, Department of Geology, Mines and Water Resources Bulletin 27:1-215 [M. Carrano/M. Carrano]more details

Purpose of describing collection: taxonomic analysis

PaleoDB collection 14376: authorized by John Alroy, entered by John Alroy on 15.05.2002, edited by Matthew Carrano, Roger Benson and Franco Aspromonte

Creative Commons license: CC BY (attribution)