Participation was certainly optional, but when the concerned citizens of Nanjemoy were meeting to discuss the BLM's involvement in the management of Potomac River lands that contain Aquia exposures, even a New Yorker's interests were piqued — it seemed relevant. So three of us (JB, GG & BH) found ourselves listening to the land management discussion. During a break, Gary turned to me (JB) and remarked that a website highlighting the Aquia fauna could be a useful tool for those arguing that public access should be permitted. Despite my reservations to starting a new project, I turned to Bill to get his opinion. It was March 2nd and we agreed to invest the time that would be required to fully research the topic and present a webpage. Rob would later join the project when stratigraphic insight was required. In looking over the final product, Gary's suggestion led far beyond our initial objectives. The presented material builds upon the foundation laid down by Ward & Wiest (1990) and will hopefully serve as a starting point for others.

Best known from cliffs exposed along the Potomac River (Virginia & Maryland) and for the teeth of Palaeocarcharodon, the Aquia has been popular to generations of collectors and paleontologists. Although the surface-collecting of beach material is most common, the faunal list as presented is based on in situ material (unless noted to the contrary). Sampling for this presentation has been largely limited to the Piscataway and lower sediments of the Paspotansa Members. Over time, upper Paspotansa observations will be incorporated on this page.

Stratigraphy

From New Jersey to Georgia, much of the Atlantic Coastal Plain lies above Late Palaeocene sediments. The various formations correspond with the embayments of the paleo-coast: Vincentown (Raritan), Aquia (Salisbury), Beaufort (Albemarle) and Black Mingo Formation (Charleston Embayment). The Southeast Georgia Embayment is represented by the Tuscahoma Frm., Nanafalia Frm. and Porters Creek Clay. In Virginia and Maryland, the Aquia is not only exposed along the Potomac, but by various creeks, rivers (Pamunkey & Rappahannock) and construction sites.

The Paleogene stratigraphy of the Salisbury Embayment has been studied and redefined continually since the nineteenth century. Ward (1985) attempted to synthesize these studies, and included in the Pamunkey Group: Brightseat Frm. (Lwr Palaeocene), Aquia Frm. & Marlboro Clay (Upper Palaeocene), Nanjemoy Frm. (Lwr Eocene), Piney Point Frm. (Mid Eocene) and Chickahominy Frm. (Upr Eocene). According to Gibson, et al (1991), in most locations, the Aquia unconformably overlies Cretaceous units; however, in a limited area east and southeast of DC, it unconformably overlies the Brightseat Formation.

The Aquia is made up of clayey, silty and shelly glauconitic sands and has been divided into 'zones' (levels/beds) which were ascribed to either the Piscataway (lower) or Paspotansa (upper) Members. Clark and Martin (1901) had attributed 'zones' 8 and 9 to the Paspotansa and the balance to the Piscataway. Ward (1985) noted that the poorly sorted sands of 'zones' 1-5 stood in contrast to the well sorted sands of 'zones' 6 & 7, and that the molluscan fauna coincidentally changed¹ across this boundary — he revised the Paspotansa to include 'zones' 6 and 7. To the casual collector, it is the abundance of Turrittella shells that alerts one to these Paspotansa sediments.

The clayey sands of 'zone' 1 (Piscataway) have limited exposures in Maryland and Virginia. More commonly exposed and collected is 'zone' 2. These shelly sands are quite rich in vertebrate material and appear to be the primary source of Palaeocarcharodon teeth. 'Zone' 3 is an indurated ledge² (limestone appearance, and when present/observable) clearly demarking the top of 'zone' 2 and bottom of 'zone' 4. 'Zone' 4 appears to be quite variable depending on depositional location (?depth). Along the Potomac (Charles County), it is a shelly sand (similar to 'zone' 2) and somewhat thick (see below image). Further inland (Prince Georges County), shell content and layer thickness diminishes. A second ledge ('zone' 5) is the upper limit of the Piscataway based on Ward (1985).

The accompanying stratigraphic chart follows Berggren et al. (1995) which splits the Palaeocene as follows: Danian (65.0 Ma to 61.0 Ma), Selandian (61.0 Ma to 57.9 Ma) and Thanetian (57.9 Ma to 54.8 Ma). Thus the Selandian is now what used to be the lower part of the Thanetian. The Aquia starts in upper NP 5, which is late Selandian, and runs through most (but not all) of the Thanetian. Because most authors have continued to employ Thanetian for the period 61.0 to 54.8 Ma, this webpage and the associated genus pages do not reflect this renaming (be it justified or not).

Depositional Environment

In Charles County, the Piscataway depositional environment is shallow marine, perhaps one to ten miles offshore. The very abundant plant debris and the occasional mammal bones and teeth indicate that land was not too terribly far away. Probably at that time, the shoreline lay roughly along the corridor of Interstate 95. Understandably, Prince Georges County marine fossils suggest shallower waters.

The three kinds of crocodiles³ indicate that the climate was much warmer than present, perhaps like south Florida, though not quite as warm as in the early Eocene. The pine cones suggest that there probably were barrier islands covered with pine forests. Most kinds of pollen were from extinct trees, but birch (Betula), alder (Alnus), and hickory (Carya) pollen have been reported. Piscataway sediments are fine to medium grained, massively bedded due to intense bioturbation, and usually abundantly glauconitic. The abundance of mollusk shells and occasional limestone-cemented beds indicate slow deposition.

Partial skeletons of crocs and turtles are fairly abundant, but almost none of them are very complete. The three mammal occurrences described by Ken Rose (2000), along with Planetochelys (a primitive box turtle) indicate at least some proximity to shore or an offshore river current bringing in carcasses. The Paspotansa appears to have been a much more offshore deposit, as wood is not very abundant and the sediments better sorted.

Chondrichthyan Fauna

Scarcity:

CLICK ON IMAGES FOR GENUS INFORMATION
—   Indicates that species not linked to a genus page.
		Ischyodus dolloi - Ratfish Ratfish material (two or three species) such as this left mandibular is present but uncommon in the Aquia.
SYNECHODONTIFORMES Duffin & Ward 1993
		Paraorthacodus clarkii EASTMAN, 1901 - Extinct shark. Uncommon in the Piscataway. Specimens have been recovered directly from 'zones' 1, 2 and 6/7.
HEXANCHIFORMES Buen 1926
		It is uncertain at this time which genera might be present in the fauna. Kent (1994) reported Notorynchus serratissimus (AGASSIZ, 1843) however the authors have been unable to confirm this observation. Two specimens, thought to represent Notidanodon (paper in process), have also been reported. Needless to say, these are rare (if present) in the fauna.
		cf Hexanchus sp - Extinct Sixgilled shark. Not previously reported from the Aquia, this upper tooth was found in situ ('zone' 7) and compares well with those of Hexanchus.
SQUALIFORMES Goodrich 1909
		Squalus cf minor (WINKLER, 1874) - Dogfish shark. Teeth of this design appear to be relatively common, at least in 'zone' 2 of the Aquia.
		"Megasqualus" orpiensis WINKLER, 1874 - Extinct dogfish shark genus. Appears to be somewhat uncommon in 'zone' 2 Cappetta has questioned the validity of the genus Megasqualus.
SQUATINIFORMES Buen 1926
		Squatina "prima" (WINKLER, 1874) - Angel shark. Teeth of this design are generally uncommon in Aquia sediments, although they appear more common in 'zone' 2.
HETERODONTIFORMES Berg 1937
		Heterodontus cf lerichei CASIER 1943 - Bullhead shark. Although uncommon in Aquia sediments along the Potomac, teeth from this species are common in 'zone' 2 deposits in Prince Georges Co. .
ORECTOLOBIFORMES Applegate 1972
		Ginglymostoma cf subafricanum ARAMBOURG 1952 - Nurse shark. Uncommon to scarce in Piscataway sediments.
		Delpitoscyllium africanum (LERICHE 1927) - Extinct nurse shark. Uncommon to scarce in Piscataway sediments.
		Palaeorhincodon wardi HERMAN, 1975 - Extinct whale shark. Kent (1994) listed this species as present in the fauna, but these authors have been unable to confirm this observation. David Ward notes (pers com 6-15-02) that wardi is an Eocene species, and if present these teeth would likely be dartevelli.
LAMNIFORMES Berg 1958
In 2005, Cappetta and Nolf released Revision de quelques Odontaspidae (Neoselachii: Lamniformes) du Paleocene et de l'Eocene du Bassin de la mer du Nord. The impact of this paper greatly effects the naming of many of the North American taxa as well. In order to judge it's relevancy and allow others to evaluate their determinations, elasmo.com provides a review of this paper.
		Anomotodon cf novus (WINKLER 1874) - Extinct goblin shark genus. Teeth from this species are common in the Aquia.
		Odontaspis winkleri LERICHE, 1905 - Smalltooth sand tiger. A common species in Piscataway sediments.
		Palaeohypotodus rutoti (AGASSIZ, 1843) - Extinct sand tiger genus. Uncommon in Aquia sediments.
		Brachycarcharias lerichei (CASIER, 1946) - Extinct sand tiger genus. Common in Aquia sediments, previously attributed to Serratolamna.
		Hypotodus verticalis (AGASSIZ, 1843) - Extinct sand tiger genus A common tooth in Aquia sediments, previously included as Carcharias hopei.
		Striatolamia striata (WINKLER, 1874) - Extinct sandtiger- like shark genus. The shark that ate the Paleogene — teeth are abundant in the Aquia.
		Striatolamia sp - Extinct sandtiger- like shark genus. This tooth-design is common in Piscataway sediments.
		Jaekelotodus robustus (LERICHE, 1921) - Extinct lamniform genus Formerly listed as Carcharias robustus, the accompanying specimen is from 'zone' 2 float.
		Isurolamna inflata (LERICHE, 1905) - Extinct mackerel shark genus. Somewhat uncommon in Aquia sediments. Illustrated teeth from 'zone' 2. Crown is smooth, more I. affinis-like in design.
		Cretalamna appendiculata (AGASSIZ 1843) - Extinct mackerel shark genus. Common in Aquia sediments.
		Otodus obliquus AGASSIZ, 1843 - Extinct mackerel shark genus. Common in Aquia sediments, accompanying specimen from Piscataway of Virginia.
		Palaeocarcharodon orientalis (SINZOW, 1899) - Extinct lamniform genus. Relatively uncommon in Aquia sediments, specimens are derived from 'zone' 2, either in situ or in float. These teeth have been reported from float thought to be Paspotansa, but the actually origin has yet to be proven.
CARCHARINIFORMES Compagno 1973
		Pachygaleus lefevrei (DAIMERIES, 1891) - Extinct houndshark genus. Teeth of this species are relatively common in Piscataway sediments.
		Galeorhinus sp. - Extinct Tope Shark The Aquia yields a number of Galeorhinus-like tooth-designs. The accompanying specimen shows similarities with G. mesetaensis NOUBHANI & CAPPETTA (1997) a Palaeocene species from Morocco.
		Palaeogaleus sp - Extinct Houndshark Uncommon in studied Piscataway sediments. Noubhani (pers. comm. 07-25-02): By its size and general morphology, it is similar to P. cf larachei NOUBHANI & CAPPETTA (1997), from the Thanetian of Morocco.
		Triakis sp - Extinct Houndshark Compares with T. antunesi NOUBHANI & CAPPETTA 1997 (Palaeocene, Morocco). Ward (pers. comm. 5-20-02) indicated that this design was listed as S. brivesi in Ward & Wiest (1990). Noubhani (07-25-2002): Undoubtedly Triakis species, but doesn't compare well with the Moroccan ones.
		? Scyliorhinus sp - Catshark. Uncommon. Labial face of crown is smooth, accompanying specimen from Paspotansa. According to Ward (pers. comm. 5-20-02), reported as Scyliorhinus gilberti CASIER, 1946 by Ward & Weist (1990). Noubhani (pers. comm. 7-25-2002) "could be a Scyliorhinus species."
		Scyliorhinus cf ptychtus NOUBHANI & CAPPETTA 1997 - Extinct Catshark. Reported by N&C (1997) as from Palaeocene & Ypresian sediments of Morocco. Accompanying image from beach below Piscataway exposures.
		Premontreia cf subulidens (ARAMBOURG, 1952) - Extinct catshark genus. Uncommon the Piscataway. Noubhani & Cappetta (1997) reported species from the Paleogene of Morocco. Kent (1999) attributed Eocene teeth of this design to P. degremonti CAPPETTA, 1992. Imaged tooth from Piscataway beach, another damaged specimen in situ 'zone' 2.
		Abdounia beaugei (ARAMBOURG, 1935) - Extinct requiem shark genus. Relatively scarce in the Piscataway, these teeth are more common in Paspotansa sediments.
Specimen required		Abdounia sp - Extinct requiem shark genus. Reported by Ward & Weist (1990).
RAJIFORMES Berg 1940
		A single specimen was reported by Ward & Weist (1990) as possibly a skate. Ward (pers. com. 2002) indicated that this may have been a smooth-crowned dasyatid. For now, the presence of "Raja" in the fauna is questionable.
MYLIOBATIFORMES Compagno 1973
		Hypolophodon cf sylvestris - Extinct stingray genus. Common in Piscataway sediments.
		Coupatezia woutersi (WINKLER, 1874) - Extinct stingray genus This species was reported by Ward & Weist (1990) from the Piscataway. The accompanying (damaged) specimen is the only 'zone' 2 example collected by this page's authors. More common in the Paspotansa.
		Dasyatis sp - Whiptail Ray The accompanying specimen is from 'zone' 2. Dasyatis teeth are uncommon in the Piscatawy.
		cf "Myliobatis" dixoni AGASSIZ, 1843 - Eagle ray genus Common in Piscataway sediments. Isolated teeth found in situ, accompanying image from 'zone' 2 float.
		"Myliobatis" sp - Eagle ray genus Common in Piscataway sediments. Isolated teeth found in situ, accompanying image from 'zone' 2 float.
		Other myliobatids Isolated myliobatid teeth are abundant in the Piscataway. However, unless these teeth have diagnostic characteristics or are part of complete tooth plates, identifications are questionable. More species may be represented than listed above.
		Undescribed myliobatoid 1 - Eagle ray genus Known from isolated teeth only ('zone' 2 and beach). These teeth were originally thought to be "M." nzadinrnsis-like in design. However, based on diagnostic characteristics, it is difficult to determine if these teeth should be placed with the myliobatids or rhinopterids.
		Rhinoptera sp - Cow-nose ray genus Common in Piscataway sediments, teeth may represent more than one species.
		"Myliobatis" sulcidens - Extinct ray species Relatively uncommon and usually as fragments only in the lower Aquia.
		Burnhamia sp - Extinct mobulid ray genus Ward & Weist (1990) reported this genus from the Paspotansa only. The accompanying specimen is from the Piscataway 'zone 2' and should be considered uncommon to scarce in the Piscataway.