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Lower Ordovician (Ibexian) trilobites from the Tribes Hill Formation, central Mohawk Valley, New York State
Canadian Journal of Earth Sciences
Abstract and Figures
The Early Ordovician Tribes Hill Formation of east-central New York State is a sequence of peritidal to subtidal carbonates and minor shales that rests disconformably on Late Cambrian carbonates and is, in turn, succeeded disconformably by Middle Ordovician strata. More than 800 trilobites from 24 collections are assigned to six species: Bellefontia gyracantha (Raymond), Clelandia parabola (Cleland), Hystricurus ellipticus (Cleland), Hystricurus cf. Hystricurus oculilunatus Ross, Symphysurina convexa (Cleland), and Symphysurina cf. Symphysurina woosteri Ulrich. Two distinct biofacies are present: the Bellefontia Biofacies in subtidal shales with thin, storm-generated bioclastic interbeds, and the Gastropod–rostroconch Biofacies in shallow, carbonate bank lithofacies. The trilobites of the Tribes Hill Formation are assigned to a single, informal biostratigraphic unit, the Clelandia parabola Fauna, which is correlative with trilobite Zone B of the Garden City Formation of Utah and with the Bellefontia franklinense Subzone of the McKenzie Hill Formation of Oklahoma.
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... The trilobite genus Symphysurina is long established as an important faunal presence in Furongian to Lower Ordovician rocks of the allochthonous successions of the Cow Head Group (Kindle and Whittington, 1958;Whittington, 1968;Fortey and Skevington, 1980;Kindle, 1982;Fortey et al., 1982;Fortey, 1983;James and Stevens, 1986;Karim, 2008) and the Cooks Brook Formation (Boyce et al, 1992). It is also well represented in co-eval autochthonous platform carbonate shelf sequences throughout the Caledonian-Appalachian-Ouachitan orogenic belt of eastern and southern Laurentia, from Greenland (Poulsen, 1927(Poulsen, , 1937Cowie and Adams, 1957;McCobb and Owens, 2008;, in revision), through Scotland (Ingham et al., 1985, to northwestern Vermont (Shaw, 1951), the Champlain Valley and Mohawk Valley of New York-Vermont (Cleland, 1900(Cleland, , 1903Fisher, 1954;Landing et al., 2003;Westrop et al., 1993), New Jersey (Weller, 1903;Westrop et al., 1993), Pennsylvania (Raymond, 1910;Butts and Moore, 1936), Maryland (Sando, 1957), West Virginia (Woodward, 1951), Virginia (Orndorf et al., 1988;Taylor et al., 1992), and Oklahoma (Stitt, 1971(Stitt, , 1977(Stitt, , 1983 in the United States. Symphysurina and other trilobites, along with brachiopods, cephalopods, corals, echinoderms and gastropods, were lately discovered in western Newfoundland in the autochthonous Watts Bight Formation, St. George Group along the south coast of the Port au Port Peninsula near Ship Cove McCobb et al., 2011) and in 2012 at Pigeon Head a little farther to the west ( Figure 1 and Plate 1). ...
... The trilobite genus Symphysurina is long established as an important faunal presence in Furongian to Lower Ordovician rocks of the allochthonous successions of the Cow Head Group (Kindle and Whittington, 1958;Whittington, 1968;Fortey and Skevington, 1980;Kindle, 1982;Fortey et al., 1982;Fortey, 1983;James and Stevens, 1986;Karim, 2008) and the Cooks Brook Formation (Boyce et al, 1992). It is also well represented in co-eval autochthonous platform carbonate shelf sequences throughout the Caledonian-Appalachian-Ouachitan orogenic belt of eastern and southern Laurentia, from Greenland (Poulsen, 1927(Poulsen, , 1937Cowie and Adams, 1957;McCobb and Owens, 2008;, in revision), through Scotland (Ingham et al., 1985, to northwestern Vermont (Shaw, 1951), the Champlain Valley and Mohawk Valley of New York-Vermont (Cleland, 1900(Cleland, , 1903Fisher, 1954;Landing et al., 2003;Westrop et al., 1993), New Jersey (Weller, 1903;Westrop et al., 1993), Pennsylvania (Raymond, 1910;Butts and Moore, 1936), Maryland (Sando, 1957), West Virginia (Woodward, 1951), Virginia (Orndorf et al., 1988;Taylor et al., 1992), and Oklahoma (Stitt, 1971(Stitt, , 1977(Stitt, , 1983 in the United States. Symphysurina and other trilobites, along with brachiopods, cephalopods, corals, echinoderms and gastropods, were lately discovered in western Newfoundland in the autochthonous Watts Bight Formation, St. George Group along the south coast of the Port au Port Peninsula near Ship Cove McCobb et al., 2011) and in 2012 at Pigeon Head a little farther to the west ( Figure 1 and Plate 1). ...
... Symphysurina sp. cf. S. convexa (Cleland, 1900), which ranges from PH-02 to PH-14 in the Pigeon Head composite section, strengthens previous correlations, as the type material of S. convexa occurs in the Tribes Hill Formation (Fisher, 1954;Westrop et al., 1993). Symphysurina convexa also occurs in the Kittatinny Formation of New Jersey where, according to Westrop et al. (1993Westrop et al. ( , page 1625, it was originally described as Illaenurus columbiana by Weller (1903, pages 133-134;Plate V, figures 1-4); the species has also been reported in West Virginia by Woodward (1951, page 214 1 Landing in Landing et al. (1996, page 676) regards Polycostatus falsioneotensis Ji and Barnes, 1994 as a junior synonym of Semiacontiodus iowensis (Furnish, 1938). ...
... 20 m. y.) is recorded in slope sequences of the Taconian allochthons. This Hatch Hill dysoxic/anoxic interval is represented by the Hatch Hill Formation [termed the "West Castleton Formation" or "Germantown Formation" in some earlier reports; Landing (1993Landing ( , 2002]. ...
... 150 m in ca. 20 m.y.) suggests that the sands and debris flows of the Hatch Hill Formation are sheet-like sandstones and debris/grain flows that originated at many points along an upper continental slope, and were not related to a persistent point source (a submarine canyon) that was fixed on the shelf margin and upper slope (Landing, 1993). ...
... and middle Saukia-equivalent Zones). The upper part of the Hatch Hill ranges into the lower Tremadocian, as indicated by the presence of early forms of the dendroid graptolite Rhabdinopora with earliest Ordovician conodonts and rare trilobites (Clelandia) (Landing, 1993;Landing et al., this volume, Stop 6.4). Although the Cambrian-Ordovician boundary is an interformational unconformity on the platform of the New York Promontory, no evidence for this unconformity exists on the east Laurentian continental slope. ...
... Order ASAPHIDA Fortey and Chatterton, 1988 Suborder ASAPHINA Fortey and Chatterton, 1988 Superfamily UNCERTAIN Family SYMPHYSURINIDAE Kobayashi, 1955 Remarks.-The superfamilial relationships of Symphysurina remain problematic (see Westrop et al., 1993). In their review of suborder Asaphina, Fortey and Chatterton (1988) recognized that the pre-occipital position of the glabellar tubercle could indicate a position within either superfamily Cyclopygacea (Cyclopygoidea) or Asaphacea (Asaphoidea). ...
The Antiklinalbugt Formation of northeast Greenland comprises peritidal to subtidal carbonate sediments, deposited in shallow shelf settings during an early Tremadocian transgressive-regressive megacycle. The succession of shales and microbial, muddy and grainy limestone, with minor dolostone at the base and top, terminates at the cryptic Fimbulfjeld disconformity. The formation has yielded trilobites collected on Ella Ø, Albert Heim Bjerge, and Kap Weber by C. Poulsen (1920s and 1930s), J. W. Cowie and P. J. Adams (1950s), and during recent field studies in 2000 and 2001. The fauna includes dimeropygids Tulepyge cowiei and T. tesella n. spp., hystricurids Millardicurus and Hystricurus , and several species of Symphysurina. Micragnostus chiushuensis (Kobayashi, 1931) is rare, as are Chasbellus sp., Clelandia sp., and Lunacrania ?. The presence of several Symphysurina species places the Antiklinalbugt Formation within the Symphysurina Zone. Chasbellus indicates the upper (lower Ordovician) part of the Symphysurina Zone for the lower upper Antiklinalbugt Formation. Conodonts place the middle lower formation in the Cordylodus intermedius conodont Biozone, the lower upper part in the Cordylodus angulatus conodont Biozone and the uppermost part in the Rossodus manitouensis conodont Biozone. This combined fauna is characteristic of the upper Skullrockian Stage of the Ibexian Series, with the lower part of the Antiklinalbugt Formation lying within the uppermost Cambrian of North America, and the upper part within the lower Ordovician. The entire formation lies within the global Tremadocian Stage of the early Ordovician.
... A single collection of fewer than 20 trilobite specimens from the base of the Jose at Hitt Canyon in the northern Franklin Mountains consists entirely of hystricurid trilobites. Although the sample size is too small to allow rigorous statistical comparison, the contrast in generic composition is remarkably similar to that documented in Skullrockian faunas in the Tribes Hill Formation of New York by Westrop et al. (1993). As in the Tribes Hill, the trilobite faunas from the Jose suggest the existence of two biofacies: one dominated by mollusks and including hystricurid trilobites, and another dominated by asaphid trilobites with a much subordinate mollusk component. ...
A revised lithostratigraphy for Lower Paleozoic strata in New Mexico and west Texas was developed through detailed sedimentological study of the Bliss and Hitt Canyon Formations within a refined temporal framework assembled from precise biostratigraphic (trilobite and conodont) and chemostratigraphic (carbon isotope) data. Member boundaries within the Hitt Canyon now correspond with mappable and essentially isochronous horizons that represent major depositional events that affected sedimentation in basins throughout Laurentian North America. This trip is designed to examine these and other important intervals, such as the extinction horizons at the base and top of the Skullrockian Stage, and to demonstrate the utility of associated faunas and isotopic excursions for correlation within and beyond the region.
The Early Ordovician (late Tremadocian; Stairsian) trilobite Gonioteloides Kobayashi has long been known from a small number of pygidia assigned to a single formally named species, and its affinities have not been assessed. Silicified material from western Utah and southeastern Idaho includes six distinct species assigned to the genus, one of which is the type species. Two others ( G . moffitti and G . pankowskii ) are new and formally named. An additional three species that are clearly new but known from sparse material are described in open nomenclature. Gonioteloides has a stratigraphic distribution through five consecutive trilobite zones in the mid-Stairsian Stage (upper Tremadocian). Although exoskeletal morphology of three species is almost completely known, the phylogenetic affinity of the taxon remains difficult to determine. It is tentatively assigned to Dimeropygidae Hupé.
UUID: http://zoobank.org/23257d6c-262b-4ef5-ae4e-cc431777e67e
The Cambrian–Ordovician boundary is a type 1 depositional sequence boundary with dramatic local erosional incision in restricted marine facies on the easternmost New York Promontory. The systemic boundary is bracketed below by Late Cambrian, upper Cordylodus proavus Zone (s.s). conodonts from carbonates of the upper Little Falls Formation (=Whitehall Formation, abandoned). Presumed Lower Ordovician ellesmeraceratoid cephalopods from the upper Little Falls are uppermost Cambrian and among the oldest known in North America. The overlying deepening–shoaling cycle of the Tribes Hill Formation (=Cutting and Great Meadows Formations, abandoned) is the local expression of a lowermost Ordovician ( Rossodus manitouensis Zone) depositional sequence recognizable across Laurentia. Complete replacement of conodonts takes place in the late Tremadocian or Tremadocian–Arenigian boundary interval with onlap of the “Fort Ann Formation” across the paleokarst cap of the Tribes Hill. The trilobites Hystricurus sp. and Symphysurina myopia Westrop new species occur in less restricted, thrombolitic facies of the middle Tribes Hill that have the highest conodont diversity. Ulrichodina Furnish, 1938, emend. is regarded as the senior synonym of the conodont Colaptoconus Kennedy, 1994 (= Glyptoconus Kennedy, 1980).
The Lower Ordovician (Ibexian) Fort Cassin Formation of New York State and Vermont consists mainly of carbonates that were deposited in a subtidal storm-influenced setting. The low diversity trilobite fauna is dominated overwhelmingly by the isoteline, Isoteloides. Eleven species representing at least nine genera are described; Acidiphorus whittingtoni is new. The bathyurine genus Goniotelina Whittington and Ross is regarded as paraphyletic and is synonymized with Acidiphorus Raymond. The presence of Isoteloides canalis (Whitfield; = I. latimarginatus Fortey), I. peri Fortey and Bathyurellus platypus Fortey indicates a correlation of the Fort Cassin with the Strigigenalis caudata Zone of the Catoche Formation of western Newfoundland.
The following new Toernquistiidae from Whiterockian (Llanvirn to lower Caradoc) strata of the Precordillera, western Argentina, are described:
Chomatopyge canasi
new species,
Lasarchopyge benedettoi
new genus and species,
Lasarchopyge correae
new genus and species,
Lasarchopyge
new species A, and
Paratoernquistia sanchezae
new genus and species. Phylogenetic analysis suggests that the Toernquistiidae Hupé, 1953 (including
Chomatopyge, Lasarchopyge, Mesotaphraspis, Paratoernquistia,
and
Toernquistia
) is closely related to but distinct from the Dimeropygidae Hupé, 1953 (including
Ischyrotoma, Ischyrophyma
and
Dimeropyge
). It is difficult to find unique synapomorphies that unite toernquistiids and dimeropygids into a monophyletic group that excludes other proetides (e.g., hystricurids), although details of their ontogenies are similar. Several species of Toernquistiidae are known from the Argentine Precordillera (one species previously described), and other species of this family have been described from Australia, Baltica, China, Kazakhstan and Laurentia. Members of the Dimeropygidae are known only from Baltica and Laurentia.
The Ordovician saw the transformation of marine benthic communities from the trilobite-based Cambrian Fauna to the brachiopod-dominated Paleozoic Fauna. An evaluation of the changing importance of trilobites during the Ordovician can be made from accurate assessments of taxonomic richness in various habitats. Here we present a new compilation of trilobite alpha diversity based on field collections and survey of the literature. The data indicate that trilobite species richness within nearshore, shallow subtidal, carbonate buildup and deep subtidal shelf environments was essentially constant between the Late Cambrian and the Late Ordovician. The alpha diversity patterns do not support the notion that trilobites became displaced from inner shelf environments during the Ordovician. Rather, the data are consistent with a decline in relative importance of the group through dilution as newly radiating invertebrate groups entered Ordovician paleocommunities. They also imply that direct interactions between elements of the Cambrian and Paleozoic faunas were not involved in the Ordovician reorganization of paleocommunities. Like many other major faunal transitions during the Phanerozoic, the Ordovician radiations appear to have been essentially non-competitive in nature.
Tremadocian onlap is recorded by the Tribes Hill Formation. The formation is a lower Lower Ordovician (upper conodont Fauna B Interval(?)- Rossodus manitouensis Zone) depositional sequence that unconformably overlies the Upper Cambrian Little Falls Formation.
Depositional environments and stratigraphy indicate that the Tribes Hill was deposited on a wave-, not tide-, dominated shelf and that a uniform, “layer-cake” stratigraphy is present. The deepening-shoaling sequence of the Tribes Hill includes the: 1) Sprakers Member (new; peritidal carbonate and overlying tempestite limestone and shale); 2) Van Wie Member (new; subtidal shale and limestone); 3) Wolf Hollow Member (revised; massive carbonates with thrombolitic cap); and 4) Canyon Road Member (new; glauconitic limestone and overlying evaporitic dolostone). The shoaling half-cycle of the Tribes Hill is older than a shoaling event in western Newfoundland, and suggests epeirogenic factors in earliest Ordovician sea-level change in east Laurentia. Conodont and trilobite biofacies track lithofacies, and Rossodus manitouensis Zone conodonts and Bellefontia Biofacies trilobites appear in the distal, middle Tribes Hill Formation.
Twenty-four conodont species are illustrated. Ansella ? protoserrata new species, Iapetognathus sprakersi new species, Leukorhinion ambonodes new genus and species, and Laurentoscandodus new genus are described.
Declining importance of trilobites was a key feature of Ordovician community “evolution”. Previous work has shown that replacement of trilobite-dominated communities by mollusc- and brachiopod-dominated communities was diachronous, occurring initially in nearshore settings. The processes responsible for these changes remain unclear, although many previous discussions have invoked some form of displacement of dominants of one community by those of another.
New data from more than thirty large collections made from nearshore facies at five localities in Canada and the northern United States indicate that, in this setting, trilobite species diversity maintained a constant low level (mean and mode of 3 species) between the Early Upper Cambrian (Marjuman) and the Late Middle Ordovician (Blackriveran). Reorganization of nearshore communites proceeded by addition of new elements, especially molluscs, from the Late Cambrian (Sunwaptan) onwards. Decline in the relative importance of trilobites was a case of dilution as species of new clades accumulated, rather than actual displacement. Trilobites appear to have been passive bystanders in Ordovician nearshore community “evolution”. Towards the end of the Ordovician, trilobites vacated nearshore environments in the Appalachian region. However, this appears to be related to environmental changes associated with progradation of clastic wedges during the development of the Taconic foreland basin.
A process of dilution may at least partly explain the offshore retreat of trilobite-dominated assemblages during the Ordovician. Offshore trilobite assemblages reached much greater species diversity than those of nearshore settings, so that their dilution via the addition of species of newly radiating clades would have proceeded more slowly. That is, trilobite-dominated paleocommunities may have persisted into the Ordovician in the outer shelf simply because this was the region in which, historically, they attained maximum species richness. Moreover, given the existence of a general pattern of increasing total species diversity of communities from nearshore to offshore sites, the tendency for newly radiating clades to attain maximum species richness offshore is not surprising: they are merely conforming to a general, environmentally-related diversity gradient that has existed throughout the Phanerozoic.
Trilobites assigned to the Elvinia Zone (Lower Franconian, Upper Cambrian) have been recovered from the Collier Shale in the Ouachita Mountains of west-central Arkansas. The trilobites are preserved as disarticulated exuviae, and are found in both dark-colored limestone clasts and dark, thinly-bedded carbonate layers. Field observations and petrologic/petrographic evidence indicate that these trilobites were originally deposited in a deep-water, outer shelf setting, and that shortly after deposition they were transported by sediment gravity flows to the continental slope or basinal plain. More than 7900 trilobites were identified during this study; they are assigned to 26 genera and 27 species. -from Authors
