Late Triassic), Near Milford, New Jersey

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Cent. Eur. J. Geosci. • 4(1) • 2012 • 3-8 DOI: 10.2478/s13533-011-0058-7

Central European Journal of Geosciences

First record of an arthropod from the Passaic Formation (Late Triassic), near Milford, New Jersey

Communication

Robert Metz1∗,

1 Department of Geology and Meteorology, Kean University Union, 07083 New Jersey, USA

Received 29 November 2011; accepted 3 February 2012

Abstract: Mudstones of the Triassic Passaic Formation, near Milford, New Jersey, have yielded the ﬁrst evidence of an arthropod impression in that formation. Associated trace fossils include Helminthoidichnites, Lockeia, Scoyenia, Spongeliomorpha, and the reptile footprint Rhynchosauroides, representing the Scoyenia ichnofacies. Associ- ated sedimentary structures include desiccation cracks and raindrop impressions. The Passaic sediments were deposited under shallow water lacustrine shoreline conditions subject to periodic subaerial exposure. Keywords: fossil arthropod impression, Passaic Formation, Triassic, New Jersey, mudstones © Versita sp. z o.o.

1. Introduction come an integral part of geologic research. As noted in many summaries, e.g., [5] ichnology comprises an impor- tant tool in identifying many physico-chemical parameters Near Milford, New Jersey, a slab representing fine- (e.g., fluvial-sediment input, wave energy, subaerial versus grained lacustrine deposits of the Late Triassic Passaic subaqueous exposure, oxygenation), especially when inte- Formation has yielded the impression of an arthropod. grated with stratigraphic and sedimentological analysis. Previous studies at this site have addressed the sedimen- As such, trace fossils are unique in that they represent tology, structure, and noted the presence of burrowing paleontologic entities as well as biogenic sedimentary [1–3], while nearby [4] detailed several trace fossils from structures [5], and contrary to body fossils trace fossils al- the Passaic Formation. ways represent in situ record of an ancient biota. Though marine studies still dominate, non-marine ichnologic re- The intent of this paper is to document, to the author’s search has greatly increased during the past decades, as knowledge, the first record of an arthropod impression from a diversity of ichnofaunas has been recorded from a va- the Late Triassic Passaic Formation of New Jersey, and riety of paleoenvironments e.g., [6–15]. However, with all to comment on the paleoenvironmental and paleoecolog- the many publications (particularly non-marine) documen- ical conditions when the arthropod was emplaced in the tation of the organism or organisms responsible for the substrate. traces is often rare or nonexistent. As such, many factors are involved including insufficient hard parts, burial envi- Ichnologic investigations of sedimentary rocks have be- ronment, reworking of the sediment, lack of quick burial, presence of scavengers, and the degree of sediment sat- ∗E-mail: [email protected] uration, among others. Besides, many of the nonmarine

3 First record of an arthropod from the Passaic Formation (Late Triassic), near Milford, New Jersey

Figure 1. Location map, showing Passaic Formation. Elevation in feet.

traces are attributed to soft-bodied organisms (e.g., an- sures of the Passaic Formation located along Spring Glen nelids, nematodes), thus oﬀering little chance for even Road (Route 627) approximately 2 km north of Milford partial preservation. in Hunterdon County, New Jersey (Fig. 1, 40◦57’22”N, 75◦10’41”W). The arthropod-bearing slab was collected from a small talus pile, and exhibited sedimentary fea- 2. Geologic setting tures similar to an exposure that is located several meters upslope which did not yield additional arthropod fossils.

The Newark basin formed during the early stage fragmen- Exposures at this location are represented by cyclical tation of the supercontinent Pangea and represents one mudstones below members L and M of the Late Trias- of the largest exposed rift basins in eastern North Amer- sic Passaic Formation [16, 22]. [1] noted that the expo- ica. The basin fill, collectively referred to as the Newark sure exhibits alternating massive, ledge-forming deposits Supergroup, is represented by more than 6 km of non- of poorly-sorted siltstone and less resistant fine-grained marine sedimentary and igneous rocks deposited over an units. Desiccation cracks are common, raindrop impres- interval of approximately 30 million years [16]. Extensive sions are also present, and most of the strata are biotur- coring by the Newark Basin Coring Project established a bated. detailed orbitally tuned geomagnetic polarity time scale and stratigraphy for the Late Triassic [16, 17]. Research on Newark basin lacustrine strata suggest 3. The specimen that the deposits exhibit evidence of being controlled by Milankovitch climate cycles, as expressed by repet- The slab on which the specimen is impressed (Fig. 2) is itive transgressive-regressive lake-level successions [16, composed of reddish-brown siltstone overlain and under- 18, 19]. The Passaic Formation represents the most lain by claystone laminae exhibiting desiccation cracks widespread and thickest (>5000 m) of these deposits, and on their upper surfaces. The arthropod (New Jersey State is made up of marginal fluvio-lacustrine and cyclical la- Museum [NJSM 23195]), preserved as an impression, is custrine reddish brown, sporadically gray, black, and tan oval in shape (Fig. 2(b)), 3.5 cm in length, and 2 cm in mudstones, sandstones and conglomerates [20]. Sedimen- maximum width, and occurs in epirelief on the reddish- tary structures include desiccation cracks, ripple marks, brown claystone. No traces of body tissue have been raindrop impressions, cross-bedding, and tool marks. Ver- found. Uneven segmentation is seen preserved across tebrate footprints, plants, fish, and conchostracans, are most of the specimen, with two of the segments observed also present [21]. The deposits of the Passaic Formation being approximately 2 mm in length. Their lack of im- reflect climate-controlled precipitation-evaporation cycles pressions of the appendages may possibly be due to the that are characteristic of smaller Van Houten cycles, which final positioning after death of the organism, or subse- in turn are modulated by the short McLaughlin cycles, and quent detachment and removal prior to burial. Along one long modulating cycles [16]. side of the specimen there is a very narrow ridge of up- The slab described in this report was collected from expo- lifted thin clay likely resulting from the arthropod being

4 Robert Metz,

(a)

(b)

Figure 2. Fossil arthropod from the Passaic Formation, Milford, New Jersey. A. Desiccation cracks on slab (yellow arrows), as well as interpreted locations where organisms rested or burrowed (white arrows), thereby inﬂuencing crack formation upon drying. Scale in mm. B. Closeup showing arthropod framed in Fig. 2(a). Note (arrow) uplifted thin clay due to pushing down of arthropod into underlying sediment. Scale in mm.

covered and gently squeezed into the underlying sedi- print Rhynchosauroides as well as desiccation cracks, tool ment (Fig. 2(b)). The slab is 1 cm thick, and approxi- marks, cross-bedding, and raindrop impressions. mately 11 X 14 cm wide. The surface of the slab does not exhibit walking or crawling traces associated with movement of the arthropod. In addition to the arthropod, the trace fossils Helminthoidichnites and Spongeliomor- 4. Discussion pha are preserved in epirelief. Upon closer inspection, the shape of the desiccation cracks exhibit patterns dif- After viewing the slab, Conrad Labandeira, David Grimaldi ferent to illustrated classic examples [23, 24], in lacking (e.g., noted that the ovoid tagma shows evidence of uneven distinctive evidence of orthogonal or nonorthogonal frac- segmentation), and Alexandr Rasnitsyn agreed that it con- ture plans. Indeed, most of them intercept locations where tains an arthropod. Interestingly, Alexander Ponomarenko organisms likely moved along, rested, or burrowed (Fig. and Kirill Eskove stated the possibility of it being a whip 2). As such, I suggest that initially these were traces ini- scorpion (personal communication, 2011), though Jason tiated by organisms which upon drying of the mud pref- Dunlop noted that the lack of a prosoma and associated erentially influenced the directions of the resultant des- appendages likely precludes such a designation (personal iccation cracks [25]. On the underside, several examples communications, 2011). Thus, unfortunately, the arthro- of the trace fossil Helminthoidichnites are present. Asso- pod cannot be identified to a lower taxonomic rank and ciated slabs exhibit the trace fossils Helminthoidichnites, is unidentifiable. Previous studies of the Passaic strata Lockeia, Scoyenia, Spongeliomorpha, and the reptile foot- making up most of this exposure [2, 26] describe it as com-

5 First record of an arthropod from the Passaic Formation (Late Triassic), near Milford, New Jersey

posed of lacustrine, fluvial, and floodplain deposits. In a variable trace [30, 40]. Interestingly, for the fossil arthro- study of Passaic trace fossils nearby the present location, pod from the Passaic Formation, no apparent evidence of [4] assigned them to the Scoyenia ichnofacies, which is such is exhibited. Thus, I suggest that in the present ex- typically affiliated with lowstand desiccated substrates in ample, the arthropod could have been carried by wind or underfilled lakes [27]. A similar assignment can be made water onto the sediment surface after death, or have been for this investigation. The Scoyenia ichnofacies relates to trapped in sediment with a degree of saturation which low energy continental sites that are subject to periodic precluded a possible escape attempt. In turn, this was submergence or emergence [9]. The combination of des- followed by desiccation and relatively rapid influx of fine iccation cracks and sporadic raindrop impressions in the sediment, such as during a rainstorm, which covered the Passaic Formation at this location denote shallow water arthropod, thus protecting the organism from scavengers conditions subject to periodic subaerial exposure. As such, and total disintegration. this would be comparable to a lacustrine regressive phase This well-preserved arthropod impression suggests that [3]. we are dealing with a post-mortem body impression, although the lack of any remnants of body tissue opens up The author has previously documented recent traces, and the question if it is a very well preserved resting track the specific organisms responsible for them, that are as- or a body fossil mould. Irrespectively of this formal con- sociated with lacustrine, pond, and puddle environments sideration, the impression with anatomical details allows [28–32], as well as trace fossils from lacustrine and flu- approximate conclusion about systematic assignment of vial paleoenvironments from the Passaic Formation e.g., the fossil. [4, 14, 33–35]. My experience has been one where evidence points overwhelmingly to insects and insect larvae, annelids, and nematodes as being the prime tracemak- ers. I have not yet detected trace fossil evidence of the actual organisms responsible including a possible arach- Acknowledgements nid tracemaker, though their evidence dates back to the Silurian. Interestingly, spiders are as widespread and as I thank Luis Buatois and Alfred Uchman for reviewing an common in nature as terrestrial insects, though far less earlier draft of this paper. I also thank Conrad Laban- well represented as fossils [36]. Although modern lake, deira, David Grimaldi, Alexander Ponomarenko, Kirill Es- puddle, and pond margins are home to diverse organisms kov and Alexandr Rasnitsyn for their identification of the which produce a diversity of traces, field experience in- fossil arthropod. I thank Rodrigo Pellegrini, New Jersey dicates that most of the superficial ones are destroyed State Museum, Trenton, New Jersey, where the arthro- due to sediment reworking, e.g. [37, 38]. In this regard, pod is housed. I thank the two anonymous reviewers for relative to ichnofossils found in lake-margin strata, [22] comments that greatly improved the manuscript. reported that this environment was subject to higher fluc- tuations in sedimentation rates, which in turn provided greater potential for fossil preservation. For terrestrial insects, winged varieties are far more abundant in the fossil record than flightless ones, though the probability for burial decreases for species that are unable to or rarely fly [39]. In turn, the author’s own field experience indicates References that the best chance for preservation of epigenic traces in continental sediments (e.g., lake or pond-margin) re- [1] Picard M.D., High L.R., Jr., Rhythmic alterations in quires almost complete desiccation followed by relatively the Triassic Chugwater and Brunswick Formations, rapid influx of covering sediment (although [39] notes that Wyoming and New Jersey. Contribution to Geology, the chemically resistant and mechanically durable chiti- University of Wyoming, 1963, 2, 87-99 nous portions of a dead insect may resist destruction for [2] Van Houten F.W., Late Triassic Newark Group, north several years before burial). Observation of modern envi- central New Jersey, and adjacent Pennsylvania and ronments indicates that a variety of animals, particularly New York. In: Subitzky, S.S. (Ed.), Geology of Se- insects, creep or walk along the shores of lakes and rivers, lected Areas in New Jersey and Eastern Pennsylva- as well as through ephemeral puddles [40]. In addition, nia. Rutgers University Press, New Brunswick, 1969, insects may even fly, or unwillingly be carried into satu- 314-347 rated, muddy sediments and respond by attempting to be [3] Olsen P.E., Paleontology and paleoecology of the set free. In most cases, in doing so, they typically leave a Newark Supergroup (early Mesozoic, eastern North

6 Robert Metz,

America). In: Manspeizer, W., (Ed.), Triassic-Jurassic tive trace fossils in Triassic lake deposits (Kyrgzstan, Rifting: Continental Breakup and the Origin of the Central Asia). Ichnos, 2010, 17, 1-11 Atlantic Ocean and Passive Margins, Part A, Devel- [16] Olsen P.E., Kent D.V., Cornet B., Witte W.K., Schlis- opments in Geotectonics. Elsevier, Amsterdam, 1988, che R., High-resolution stratigraphy of the Newark 185-230 rift basin (early Mesozoic, eastern North America). [4] Metz R., Scoyenia ichnofacies from the Passaic For- Geol. Soc. Am., 1996, 108, 40-77 mation (Upper Triassic) near Milford, New Jersey. [17] Kent D.V., Olsen P.E., Astronomically tuned geomag- Northeastern Geology, 1989, 11, 212-217 netic polarity time scale for the Late Triassic. J. Geo- [5] MacEachern J.A., Pemberton S.G., Gingras M.K., phys. Res., 1999, 104, 12,831-12,841 Bann K.L., The ichnofacies paradigm: A fifty-year [18] Van Houten F.B., Cyclic lacustrine sedimentation, retrospective. In: Miller, W., III, (Ed.), Trace Fossils: Upper Triassic Lockatong Formation, central New Concepts, Problems, Prospects. Elsevier B.V., Amster- Jersey and adjacent Pennsylvania. Kans. Geol. Sur. dam, 2007, 52-77 Bull., 1964, 169, 497-531 [6] Pieńkowski G., Early Liassic trace fossil assemblages [19] Olsen P.E., A 40-million year lake record of early from the Holy Cross Mountains, Poland: Their dis- Mesozoic orbital forcing. Science, 1986, 234, 842- tribution in continental and marginal marine envi- 848 ronments. Soc. Econ. Paleontologists Mineralogists [20] Olsen P.E., Field Guide for Non-marine Boundary Spec. Paper 35, 1985, 37-52 Events in the Newark Basin (New Jersey, Pennsyl- [7] Frey R.W., Pemberton S.G., The Psilonichnus ichno- vania, and Connecticut), Eastern United States and coenose, and its relationship to adjacent marine and their Litho-, Chrono- and Biostratigraphic Context. nonmarine ichnocoenoses along the Georgia coast. Guidebook for Field Workshops of IGCP 458, 2002, Bull. Can. Petrol. Geol., 1987, 35, 333-357 1-106 [8] Pickerill R.K., Carboniferous nonmarine invertebrate [21] Olsen P.E., Flynn J.J., Field guide to the vertebrate ichnocoenoses from southern New Brunswick, eastern paleontology of Late Triassic age rocks in the south- Canada. Ichnos, 1992, 2, 21-35 western Newark basin (Newark Supergroup, New [9] Buatois L.A., Mángano M.G., The paleoenvironmen- Jersey and Pennsylvania). The Mosasaur, 1989, 4, tal and paleoecological significance of the lacus- 1-43 trine Mermia ichnofacies: an archetypical subaque- [22] Olsen P.E., Newark basin, New Jersey. In: Olsen, ous nonmarine trace fossil assemblage. Ichnos, 1995, P.E., Schlische, R., Gore P.J. (Eds.), Tectonic, Depo- 4, 151-161 sitional, and Paleoecological History of Early Meso- [10] Keighley D.G., Pickerill R.K., Systematic ichnology of zoic Rift Basins, Eastern North America. 28th IGC the Mabou and Cumberland Groups (Carboniferous) Guidebook T-351, 1989, 2. of western Cape Breton Island, eastern Canada, 1: [23] Lachenbruch A.H., Mechanisms of thermal contraction Burrows, pits, trails, and coprolites. Atlantic Geol., cracks and ice wedge polygons in 1997, 33, 181-215 permafrost. Geological Society of America Special [11] Genise J.F., Mángano M.G., Buatois L.A., Laza J., Paper 70, 1962, 1-69 Verde M., Insect trace fossil associations in pale- [24] Allen J.R.L., Sedimentary Structures Their Character osols: the Coprinisphaera ichnofacies. Palaios, 2000, and Physical Basis. Developments in Sedimentology 15, 33-48 30. Elsevier, Amsterdam, 1984, II, 544-554 [12] Uchman A., Pika-Biolzi M., Hochuli P.A., Oligocene [25] Metz R., Control of mudcrack patterns by beetle lar- trace fossils from temporary fluvial plain ponds: An vae traces. J. Sediment. Petrol., 1980, 50, 841-842 example from the freshwater molasse of Switzerland. [26] Olsen P.E., Van Houten F.B., Field guide to the Late Eclogae Geol. Helv., 2004, 97, 133-148 Triassic portion of the Newark basin section in the [13] Kim J.Y., Keighley D.G., Pickerill R.K., Hwang W., Kim Delaware Valley, New Jersey. In: Husch, J., and K.S., Trace fossils from marginal lacustrine deposits Hozik, M., (Eds.), Geology of the Central Newark of the Cretaceous Jinju Formation, southern coast of Basin: 5th Annual Meeting of the New Jersey Geo- Korea. Palaeogeogr. Palaeocl., 205, 218, 105-124 logical Association, Rider College, Lawrenceville, NJ, [14] Metz R., Late Triassic invertebrate trace fossils from 1988, 233-289 lacustrine shoreline deposits, Smith Clark Quarry, [27] Buatois L.A., Mángano M.G., Invertebrate ichnology Milford, New Jersey. Northeastern Geology and En- of continental freshwater environments. In: Miller, vironmental Science, 2007, 29, 1-14 W., III, (Ed.), Trace Fossils: Concepts, Problems, [15] Voigt S., Hoppe D., Mass occurrence of penetra- Prospects. Elsevier B.V., Amsterdam, 2007, 285-323

7 First record of an arthropod from the Passaic Formation (Late Triassic), near Milford, New Jersey

[28] Metz R., Sinusoidal trail formed by a recent biting line deposits of the Passaic Formation, Douglassville, midge (Family Ceratopogonidae): trace fossil impli- Pennsylvania. Ichnos, 2000, 7, 253-266 cations. J. Paleontol., 1987, 61, 312-314 [36] Zherikhin V.V., Characters of insect burial. Super- [29] Metz R., Recent traces by invertebrate in aquatic order Thripidea Fallen, 1814. Insects in the terrestrial nonmarine environments. Bull. NJ. Acad. Sci., 1987, ecosystems. In: Rohdendorf, B.B., Rasnitsyn, A.P., 32, 19-24 (Eds.), Historical Development of the Class Insecta. [30] Metz R., Insect traces from nonmarine ephemeral pud- Trudy Paleontol. Inst. Akad. Nauk SSSR 175. Nauka, dles. Boreas, 1987, 16, 189-195 Moscow, 1980, 7-18, 69-72, 189-224 [31] Metz R., Tunnels formed by mole crickets (Orthoptera: [37] Frey R.W., Pemberton S.G., Fagerstrom J.A., Morpho- Gryllotalpidae): paleoecological implications. Ichnos, logical, ethological, and environmental signiﬁcance of v. 1, p. 139-141. the ichnogenera Scoyenia and Ancorichnus. J. Pale- [32] Metz R., 2002, Nonmarine Cretaceous Protovirgu- ontol., 1984, 58, 511-528 laria: Possible dragonﬂy larva tracemaker. Ichnos, [38] Bromley R.G., Trace Fossils: Biology, taphonomy and 2002, 9, 75-76 applications. Chapman and Hall, London, 1996, 1-361 [33] Metz R., A new ichnospecies of Spongeliomorpha [39] Zherikhin V.V., Pattern of insect burial and conserva- from the Late Triassic of New Jersey. Ichnos, 1993, tion. In: Rasnitsyn, A.P., Quicke, D.L.J., (Eds.), History 2, 259-262 of Insects. Kluwer Academic Publishers, Dordrecht [34] Metz R., Newark basin ichnology: the Late Tri- 17-63 assic Perkasie Member of the Passaic Forma- [40] Chamberlain C.K., Recent lebensspuren in nonmarine tion, Sanatoga, Pennsylvania. Northeastern Geology, aquatic environments. In: Frey, R.W., (Ed.), The Study 1996, 18, 118-129 of Trace Fossils. Springer-Verlag, New York, 1975, [35] Metz R., Triassic trace fossils from lacustrine shore- 431-458