Friday, June 29, 2012

The Eurypterid “Eurypterus remipes” is the Official Fossil of the State of New York: Part III – The R.A. Langheinrich Museum of Paleontology in Eastern Central New York


The honor of “Official Fossil of the State of New York” was bestowed upon Eurypterus remipes in 1984, attributable to its abundance within the state’s borders. Now extinct, eurypterids were marine arthropods that bore a striking resemblance to contemporary scorpions, evolutionary relatives classified within a sister taxon. “Sea scorpions,” as they are affectionately called, reached their heyday of diversity during the Silurian Period and their demise during the Great Dying of the Permian along with 96% of marine species. In spite of their wealth of preservation within the state, eurypterid paleobiology, ecology and environments have remained a source of conjecture and speculation.

Many of this eurypterid’s spinose appendages are missing, the integument of the carapace has partially flaked off and the telson is almost severed, all possibly due to disarticulation, transportation and burial. This fossil measures about four inches, whereas members of the species are thought to reach two feet. Of the six pairs of grasping, walking and swimming appendages (legs), five pairs are visible.
(From my personal collection from Lang’s Quarry)

THREE POSTS ON EURYPTERIDS
In my first post (Part I), I discussed basic evolution, phylogeny, morphology and tectonics of the eurypterids of New York (http://written-in-stone-seen-through-my-lens.blogspot.com/2012/05/eurypterus-remipes-official-fossil-of.html).

In my previous post (Part II), I received a private tour of the Lang Quarry, located just south of Ilion in Herkimer County of eastern Central New York at a famous outcrop known as Passage Gulf. Eurypterids are found within the thinly stratified, limy muds of the quarry's waterlimes (http://written-in-stone-seen-through-my-lens.blogspot.com/2012/06/eurypterid-eurypterus-remipes-is.html.

In this final post on eurypterids (Part III), I headed to the nearby R.A. Langheinrich Museum, the repository for almost three decades of excavating, preparing and studying eurypterids by Allan Lang, its owner and curator.


 
Dorsal and ventral aspects of Eurypterus tetragonophthalmus from Jan Nieszkowski's 1858 dissertation
(From wikidedia.com)

THE R.A. LANGENHEINRICH MUSEUM OF PALEONTOLOGY
Allan and Iris Lang maintain the R.A. Langheinrich Museum of Paleontology (Allan’s more-difficult-to-pronounce official surname). The museum not only includes an incredible assortment of eurypterids from the quarry but Allan’s enormous collection of meteorites from around the world. Allan is a skilled metal worker, and many of the meteorites have been sliced into thin sections for viewing.

Allan (below) is proudly posing with a cast of a gigantic Pterygotus (Acutiramus). The over seven foot tall fossil is actually a composite that was assembled from three slabs of dolostone from the Lang Quarry and is the largest of its kind ever found. The original resides as the centerpiece of the Royal Ontario Museum’s paleontological exhibit.

Allan Lang and the massive Pterygotus that he excavated from his quarry
(Photographed at the R.A. Langheinrich Museum of Paleontology)

For size comparison notice two small eurypterids and the disarticulated carapace (head structure) alongside the composite. Gigantism reflected in Middle Paleozoic marine eurypterids such as Pterygotus was a foreshadowing of the enormous size that existed amongst Late Paleozoic terrestrial arthropods such as "monster millipedes, colossal cockroaches and jumbo dragonflies" (Braddy, 2007).

Giant arthropods from the fossil record compared with average height of a human male (British):
(a) the eurypterid Jaekelopterus rhenaniae, Early Devonian, Germany; (b) the trilobite Isotelus rex, Late Ordovician, Manitoba, Canada; (c) the dragonfly Meganeura monyi, Late Carboniferous, France; (d) the millipede Arthropleuro armata, Late Carboniferous, Europe. Scale bar (a-d), 50 cm.
(From Braddy, 2007)

Model of a gigantic, yet life-sized Pterygotus eurypterid
(Smithsonian Institution’s Museum of Natural History.

The eurypterids of Passage Gulf
The eurypterids of New York were originally thought to be preserved within two “pools” which are now considered to be distinct stratigraphic horizons. The eurypterids listed below were considered representative of the “Herkimer pool” (from Herkimer County) of New York, the eastern locality such as Passage Gulf. Eurypterids found in western localities of the “Buffalo pool” include Hughmilleria, Paracarcinosoma and Eurypterids such as lacustris:

The three eurypterid families most commonly found at Lang’s Quarry of Passage Gulf:
 1.) Pterygotus possessed narrow, spine-less walking legs, a rounded-trapezoidal head (carapace) with compound eyes near its margin, a flattened and expanded tail (telson) with a dorsal-keel down the midline, and most notably, a pair of large chelicerae claws in front of the mouth fortified by the presence of large, well-developed teeth. Its size ranged from a few inches to well over 3 feet with gigantic specimens exceeding 7 feet. Based on partial remains, Pterygotids likely exceeded 10 feet in length. An example is Acutiramus macrophthalmus

2.) Eurypterus, the most common eurypterid of the Fiddlers Green Formation, comprising 90-95% of the Bertie Group eurypterids, possessed spinose appendages, more centrally-located eyes, a pointed tail and larger swimming paddles. Its size ranged from under an inch to a foot or two in length. An example is Eurypterus remipes

3.) Dolichopterus had compound eyes located near the edge of its prosoma, stout spinose-walking legs, swimming legs with serrated margins, a somewhat flattened carapace, lateral projections on its abdominal segments and a lance-like tail. Its size ranged from under an inch to about one foot. An example is Dolichopterus jewetti

Pterygotus, Eurypterus and Dolichopterus
(Modified from Ernst Haeckel’s Kunstformen der Natur, 1904)

THE BERTIE BIOTA
The Late Silurian Bertie Group of New York, in particular its muddy dolostones called waterlimes, supported (or at least preserved) a rich eurypterid biota (see my two previous posts for details). Although the waterlime fauna and flora are considered to have been sparse, members of the marine paleocommunity in addition to eurypterids included horseshoe crabs, scorpions, phyllocarid crustaceans, a Lichid trilobite, gastropods, orthocone cephalopods, Lingulid brachiopods, ostracodes, graptolites, bryozoan corals, fish (rare in New York), stromatolites and other algal forms. Cooksonia, which grew in dense mats along the shoreline and considered to be amongst the earliest plant “pioneers” on land, has been recovered from waterlime deposits.

Cooksonia
(Photographed at the R.A. Langheinrich Museum of Paleontology)
This model depicts a eurypterid venturing onto land with Cooksonia growing along the shoreline.
(Smithsonian Institution’s Museum of Natural History)

SHEDDING ONE’S CHITINOUS SKIN
This slab of waterlime displayed in the museum contains a multitude of molted eurypterids and a disarticulated carapace. In fact, most eurypterid fossils are presumed to be molted exoskeletons as opposed to carcasses (Braddy, 1995; Ciurca personal communication, 2012). The problem of distinguishing between eurypterid exuviae and carcasses has remained a paleontological exercise for almost a century (Clarke and Ruedemann, 1912; Tetlie, 2008). One of the challenges is that eurypterid exuviae, like horseshoe crabs, remain so intact defying inclinations to label them as molts.

Typical of all arthropods, eurypterids shed or molted their chitinous, semi-rigid exoskeletons in order to accommodate growth. Similar to cellulose in its supportive function, chitin is a modified polysaccharide like glucose that contains nitrogen. Contemporary horseshoe crabs (Xiphosurans) and scorpions (Arachnids) are frequently used, phylogenetically-related, modern-analogues for investigating aspects of eurypterid paleo-biology, ecology and behavior (Braddy, 2001; Tetlie 2008). Horseshoe crabs molt perhaps 10 times in its lifetime which provides some explanation for the vast numbers of preserved exoskeletons. 

Amongst the articulated eurypterid molts, notice the disarticulated carapace and the beautifully preserved spinose appendages. The chitinous exoskeletons have a brown color largely due to carbonization. The original components of the cuticle have undergone in situ polymerization during diagenesis (Gupta, 2007). The prevalence of "ventral-up" specimens is not necessarily an indication of supine-ecdysis (Tollerton, 1997) but may be related to transportation and burial (Tetlie, 2007).
(Photographed at the R.A. Langheinrich Museum of Paleontology)

The actual shedding event is called ecdysis, whereas molting is the term reserved for the entire process that includes a period of inactivity both before and after ecdysis. Molting subjects arthropods to susceptibility from predation during the soft-shell stage. With horseshoe crabs, refugia are sought out, regions in which to safely molt. Reduction of suitable refugia near the end of the Silurian has been cited as a potential cause for eurypterid decline and extinction of some genera (Tetlie, 2007), although others site their decline to quicker, more heavily-armored fish prototypes that developed during the Devonian.

Recurrent patterns of disarticulation and telescoping of exoskeletal elements are some of the means used to distinguish fossil-exuvia from fossil-carcasses. Analyses of eurypterid exoskeletons, which at first appears to be a random dissociation, is in reality a non-random taphonomic pattern that suggests the underlying biological process of ecdysis (Tetlie, 2007).

Molting follows a sequence of events beginning when feeding and activity stops, and a tear develops in the anterior carapace margin. Eventually, the animal emerges from the molted exoskeleton (exuvia). Current thinking (Brady, 2001) considers the “Bertie” assemblages to consist predominantly of exuviae due to lack of scavenging, frequent crumpling, partial telescoping and dispersal of disarticulated remains.

WINDROWS
Eurypterid fossils frequently occur in linear aggregations called “windrows” (Ciurca). It is believed that this is an indication of current or storm-related transportation and orientation into the area of deposition (Tetlie and Ciurca, 2005). Hence, the entombing stratum is classified as a tempestite. Contemporary windrows of fragmentary, current-sorted bivalves, crabs and marine debris can be seen while strolling along the Atlantic shore after a tide or storm as seen below. These shoreline deposits ("strandlines") are segregated by weight and size (Ciurca personal communication, 2012). The waterlimes of New York are quite unusual and not your typical beach deposit. They are peculiar carbonates deposited in peculiar lagoons that researchers are still trying to understand today.



DEATH ASSEMBLAGES, MASS MOLTS OR BREEDING GROUNDS?
Displayed in the museum are two incredible mirror-image slabs of Bertie waterlime that contain a half-dozen articulated molts and sundry disarticulated bodyparts. Deceivingly, the two halves are not positive and negative casts of upper and lower members of strata entombing the fossils, but are “part” and “counterpart” slabs with each containing a portion of the preserved eurypterids. This is likely a small section of a windrow.

(Photographed at the R.A. Langheinrich Museum of Paleontology)

One of the many questions surrounding eurypterids is whether large aggregations of molts are reflective of refugia or transportation from a freshwater estuary to a region of hypersaline waterlime for burial. Not surprisingly, other hypotheses exist. Based on fossil remains (which may falsely confer a taphonomic or collection bias), one theory suggests that “breeding grounds” were utilized in mudflats and sandbars for survival protection accounting for the large eurypterid assemblages (“mass molts”) or for ecdysis (“mass molts”) (Braddy, 2001). Mass mortality (“death assemblages”) seems less likely an explanation, since the remains are concentrations of exuviae rather than carcasses (Vrazo, 2011). As mentioned, possibly storms brought exuviae down river into muddy deltaic sediments near and offshore for burial, even additionally mixing with marine biotas (Ciurca, 2010). Horseshoe crabs were transported and preserved in the hypersaline Jurassic lagoons of Solnhoffen (Barthel, 1994).

(Photographed at the R.A. Langheinrich Museum of Paleontology)

THE APPENDAGES OF PTERYGOTUS
This massive Pterygotus chelicera-claw includes both a fixed and free ramus as well as a full array of formidable denticles (teeth). Some researchers have questioned the common belief that Pterygotids were the high-level predators once thought based upon tests showing the lower mechanical advantage of its claw. In addition, due to its lack of an “elbow joint”, its limited movement would have made it more adept at grasping than capturing its prey. In fact, they posed that Pterygotids may have been scavengers (Laub et al, 2010).

(Photographed at the R.A. Langheinrich Museum of Paleontology)

This museum specimen is a large, distinctive swimming leg, the sixth prosomal appendage, of Pterygotus.

(Photographed at the R.A. Langheinrich Museum of Paleontology)

Notice the expansion on the last segment of Pterygotus’ swimming-leg and the numerous serrations on its marginal aspect (below). Not to deny the animal’s aquatic capabilities, but upon observing the serrations on the outermost aspect of the leg, I can’t help but wonder if the “swimming” leg was equally or better suited as a “crawling” or “digging” leg. Such are the challenges associated with attempting to reconstruct an animal’s ecology and behavior from fossilized remains.


SEX AND THE EURYPTERID
This large structure (almost two feet across) is a eurypterid’s genital appendage located on the median ventral surface of the abdomen. Eurypterids were thought to be sexually dimorphic differentiated by genitalia of varying lengths. Numerous opinions exist concerning the exact nature of the appendage. If from a male, its clasper might grasp the female during mating, might be used in immobilization-defense of being eaten by the female during courtship, or be associated with the discharge of sperm or the transfer of a spermatophore (an advanced mode of external fertilization seen in crustaceans). If belonged to a female, it might have functioned to scoop out a hollow in the substrate in anticipation of fertilization. Extant horseshoe crabs mate annually en masse at specific breeding sites that coincide with lunar and tidal rhythms (Rudloe, 1980). They lay their eggs in clusters of nests along the beach (Shuster, 1982).

(Photographed at the R.A. Langheinrich Museum of Paleontology)

A FRESH, BRACKISH OR SALT WATER HABITAT?  
Late Silurian waterlimes are thought to have been brackish to hypersaline based upon the prevailing arid landscape and basins of evaporite deposits, salt hoppers and mud cracks without access to normo-saline seas. A slab of waterlime from the quarry was sectioned (below) by Allan and shows a vesicular cavity presumably formed by the dissolution of an evaporite such as crystalline halite. Did eurypterids live under these highly saline conditions, were they saline-tolerant visitors or were they washed down from freshwater estuaries and deposited in windrows?

(Photographed at the R.A. Langheinrich Museum of Paleontology)

MARINE SCORPIONS
In this slab of dolostone from Lang’s quarry, a few eurypterids and disarticulated bodyparts are preserved in conchoidal areas (Allan’s “dishes”). Easy to overlook is the small marine scorpion at the upper left. This confirms that both of these related chelicerates coexisted as members of the same paleocommunity and at a time period before scorpions had conquered the land. The first marine scorpions evolved from stem-group chelicerates along with eurypterids during the Middle Silurian (about 428 Ma), and terrestriality was acquired by 340 Ma.

(Photographed at the R.A. Langheinrich Museum of Paleontology)

This is a close-up of the scorpion seen above next to disarticulated eurypterid segments. Scorpion fossils from the Silurian and Devonian are exceedingly rare partially due to their lack of a mineralized integument. Scorpions, along with spiders, are arthropods within Class Arachnida, the sister taxon of eurypterids. Both possess four pairs of walking legs. Recall that their inclusion within subphylum Chelicerata is based upon the small anterior appendages used to grasp food. Their second appendages are pedipalps (or chelae) that function as the distinctive pincers. Currently, three different species are known from the Bertie Waterlime.




LANG’S QUARRY AND THE R.A. LANGHEINRICH MUSEUM OF PALEONTOLOGY
The Lang’s facility is open by appointment only. Contact information is available on their website. 

SUGGESTED READING
Distribution and Dispersal History of Eurypterida (Chelicerata) by O. Erik Tetlie, 2007.
Testing the Mass-Moult-Mate Hypothesis of Eurypterid Paleoecology by Matthew B. Vrazo and Simon Braddy, 2011.
The Eurypterida of New York VI by Clarke and Ruedemann, 1912.
The Rise and Fall of the Taconic Mountains by Donald Fisher, 2006.
Geology of New York by Y.W. Isaachsen et al, 2000.
The Trilobites of New York by Thomas E. Whiteley, 2002.
Eurypterids Illustrated by Samuel J. Ciurca, Jr., 2008-2010.
Fieldtrip Guidebook, NYS Geological Association, Fiftieth Annual Meeting (1978), Fifty-fourth (1982), Sixty-second (1990), Sixty-sixth (1994) for publications by Samuel J. Ciurca, Jr.

SUGGESTED WEBSITES
Eurypterid.net and eurypterids.net/EurypteridLinkIndex.html by Samuel J. Ciurca, Jr.
Statefossil.org/news.htm by Allan and Iris Lang

ACKNOWLEDGEMENTS
I wish to thank Allan and Iris Lang for their time and generosity in making their incredible collection at the museum available for viewing and photography. I also want to thank Allan for his private tour of the quarry.

Many thanks also to paleontologist Samuel J. Ciurca, Jr. of Rochester, New York for his personal communications. Sam has been studying, collecting, meticulously documenting and publishing on eurypterids, their associated flora and fauna, and the entombing stratigraphy for over 50 years. He has donated thousands of specimens from his personal collection to institutions such as the Yale Peabody Museum’s Division of Invertebrate Paleontology recognized as the Ciurca Collection, the Smithsonian Institution and the Buffalo Museum of Science.


3 comments:

  1. Wonderful article & photos. I went to Bennett High School in Buffalo which, I found out in college, was built on a filled quarry from which eurypterid fossils were found. Some are now in the Buffalo Museum of Science. I've retained a fondness for these amazing animals since college.

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  2. Thanks for visiting and your comment! It's quite possible that Sam Ciurca donated those fossils! Doctor Jack

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  3. I recall visiting Bennett Quarry in Buffalo in about 1975 on a geology class field trip, led by TX Grasso of Monroe Community College in Rochester. Sam Ciurca met the class there that day (or was there collecting) and gave us a tour of the quarry. We had a broad ranging discussion on the paleo-environment of the Bertie Waterlime.
    Thank you for a well written, well researched, and informative geoblog.

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