FIG 1 - uploaded by Ed Landing
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Map showing location of measured sections. CCr, Canajoharie Creek (locality 9, Fisher 1980); FC, Flat Creek (locality 11, Fisher 1980); BR, Van Wie Creek at Borden Road (locality 13, Fisher 1980); NY67, quarry on New York Highway 67 (locality 14, Fisher 1980); ARC, road cut on New York Highway 5, Amsterdam (locality 16, Fisher 1980).
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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: Bellefonti...
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... in the studies of sequences in the western (Ross 1951;Hintze 1953) and southern (Stitt 1977(Stitt , 1983) United States which laid the foundations of North American Lower Ordovician trilobite biostratigraphy. Here, we revise the trilo- bites of the Tribes Hill Formation using new collections from stratigraphic sections at five localities ( Fig. 1) and document their abundance and distribution patterns. A subsequent paper (Landing et al.') will deal with the stratigraphy of the Tribes Hill Formation and its conodont ...
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... study includes both new collections and material obtained by Fisher (1952) from exposures at the Tribes Hill Quarry that are no longer extant (see Fig. 1 ...
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... depression" of Norford 1969, p. 5) is poorly defined on testate surfaces (Pl. I, fig. 2). The holotype of C. parabola (see Norford 1969, P1. 1, figs. 1, 6, 11, and 12) is exfoliated but new testate material (Pl. 1, fig. 2) has pitted prosopon similar to that of specimens from Oklahoma that were assigned to this species by Stitt (1983, P1. 6, figs. 1 and ...
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... (subfamily Niobinae; Whittington 1965, P1. 25, fig. 7), suggesting that this character state is plesiomorphic. The hypostome of Symphysurina (Westrop, in press) is relatively long (sag.) with narrow borders, as in the ceratopygid outgroup (see Pratt 1992, P1. 8, figs. 8 -10); by contrast, nileid hypostomes (Fortey 1975, P1. 11, fig. 3, P1. 12, fig. 6, P1. 13, fig. 8, P1. 20, fig. 6, P1. 21, fig. 9; seealso Whittington 1965, P1. 31, fig. 6, P1. 35, fig. 6) are relatively broad (tr.) with wide posterior borders (see also Fortey and Chatterton 1988, p. 199). Fortey (1983) also drew attention to the relatively small posterior fixed cheeks of Symphysurina, a condition which is also duplicated in the Nileiidae. fig. 1, ...
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... state is plesiomorphic. The hypostome of Symphysurina (Westrop, in press) is relatively long (sag.) with narrow borders, as in the ceratopygid outgroup (see Pratt 1992, P1. 8, figs. 8 -10); by contrast, nileid hypostomes (Fortey 1975, P1. 11, fig. 3, P1. 12, fig. 6, P1. 13, fig. 8, P1. 20, fig. 6, P1. 21, fig. 9; seealso Whittington 1965, P1. 31, fig. 6, P1. 35, fig. 6) are relatively broad (tr.) with wide posterior borders (see also Fortey and Chatterton 1988, p. 199). Fortey (1983) also drew attention to the relatively small posterior fixed cheeks of Symphysurina, a condition which is also duplicated in the Nileiidae. fig. 1, P1. 1 1, fig. 1, P1. 12, figs. 1 and5, P1. 13, figs. 1 and7, P1. 15, fig. ...
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... 8, P1. 20, fig. 6, P1. 21, fig. 9; seealso Whittington 1965, P1. 31, fig. 6, P1. 35, fig. 6) are relatively broad (tr.) with wide posterior borders (see also Fortey and Chatterton 1988, p. 199). Fortey (1983) also drew attention to the relatively small posterior fixed cheeks of Symphysurina, a condition which is also duplicated in the Nileiidae. fig. 1, P1. 1 1, fig. 1, P1. 12, figs. 1 and5, P1. 13, figs. 1 and7, P1. 15, fig. ...
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... P1. 35, fig. 6) are relatively broad (tr.) with wide posterior borders (see also Fortey and Chatterton 1988, p. 199). Fortey (1983) also drew attention to the relatively small posterior fixed cheeks of Symphysurina, a condition which is also duplicated in the Nileiidae. fig. 1, P1. 1 1, fig. 1, P1. 12, figs. 1 and5, P1. 13, figs. 1 and7, P1. 15, fig. ...
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... suboval in outline. The hypo- stome of Bellefontia (Pl. 2, fig. 8) is subquadrate in outline with narrow borders and is therefore most similar to the rela- tively plesiomorphic ceratopygid morphology; oval or forked hypostomes are characteristic of asaphids (see, for example, Hintze 1953, P1. 11, figs. 5 and 12, P1. 12, figs. 4 and 11, P1. 13, fig. 4, P1. 15, fig. 8; Robison and Pantoja-Alor 1968, P1. 98, figs. 6, 7, and 18; Fortey and Owens 1991, figs. 7f, 8b), whereas cyclopygaceans have broad hypostomes with wide borders (see above). The presence of eight thoracic seg- ments in Bellefontia (Hintze 1953) is consistent with an assign- ment to the Asaphacea as conceived by Fortey and Chatterton, ...
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... (Hintze 1953) is consistent with an assign- ment to the Asaphacea as conceived by Fortey and Chatterton, although eight segments are also present in some species of Symphysurina (Hintze 1953), which they placed in the Cyclo- pygacea. The evenly rounded anterior cranidial margin, which occurs also in cyclopygaceans (Whittington 1965, P1. 32, figs. 1 -3, P1. 34, figs. 3 and 4) and ceratopygids (Hughes and Rushton 1990, Text Fig. 5), is likely to be plesiomorphic and is unlike the triangular apex typical of asaphids (see, for exarn- fig. 6). In the absence of definitive character support for superfamily assignment, it seems best that Bellefontia be left unclassified for the present. GENUS ...
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... convexa is characterized by pitted prosopon that is faint on external surfaces; more clearly defined pits are also evident on parietal surfaces. Illaenurus columbiana Weller (1903, P1. 5, figs. 1 -4), from the Beekmantown Group of New Jersey, may be a junior synonym of S. convexa, as sug- gested by Raymond (1910), but a final decision must await discovery of additional material. Among other pitted species, Symphysurina bulbosa Lochman (1964, P1. 66, figs. 4-8; Stitt 1977, P1. 5, figs. 5 and 6), is characterized by a much narrower ...
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... (see also Kobayashi 1955, p. 440). Dean (1989) included Xenostegium douglasensis Walcott in Kobayashia, but this species has an evenly rounded anterior cranidial margin ( Walcott 1925, P1. 24, fig. 22) and thus is better assigned to Bellefontia (see also Kobayashi 1955, p. 442 FIGS. 1 -15. Bellefontia gyracantha (Raymond). All from collection CCr 5.7, except (1, 3, 4, 6) from BR 1.35, (2) from "upper bed," Tribes Hill Quarry, and (8, 14) from ARC 5.75. (1, 6) Cranidium (E (exfoliated material) For personal use ...
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... to X. douglasensis by Walcott (1925, P1. 24, fig. 23; see also Dean 1989, P1. 40, figs. 5 and 9) has a minute median pygidial spine comparable to that of Bellefontia acuminiferentis Ross (1951, P1. 25, figs. 6-9) and it is possible that these two species will prove to be synonyms. The monotypic genus Parabellefontia Hintze (1953, P1. 3, figs. 1-6; Dean 1989, P1. 41, figs. 1-14) differs from Bellefontia by effacement of cephalic border and axial furrows and the axial furrows of the pygidium. Bellefontia gyracantha (Raymond; P1. 2, figs. 1 -15) from the Tribes Hill Formation occupies an intermediate morphological position between Para- bellefontia and more strongly furrowed representatives of Bellefontia, such ...
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... (1951, P1. 25, figs. 6-9) and it is possible that these two species will prove to be synonyms. The monotypic genus Parabellefontia Hintze (1953, P1. 3, figs. 1-6; Dean 1989, P1. 41, figs. 1-14) differs from Bellefontia by effacement of cephalic border and axial furrows and the axial furrows of the pygidium. Bellefontia gyracantha (Raymond; P1. 2, figs. 1 -15) from the Tribes Hill Formation occupies an intermediate morphological position between Para- bellefontia and more strongly furrowed representatives of Bellefontia, such as B. chamberlaini Clark (Hintze 1953, P1.4, figs. 11 -13): effacement is restricted to the cranidial and, to a lesser extent, pygidial axial furrows; cephalic and ...
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... differs from Bellefontia by effacement of cephalic border and axial furrows and the axial furrows of the pygidium. Bellefontia gyracantha (Raymond; P1. 2, figs. 1 -15) from the Tribes Hill Formation occupies an intermediate morphological position between Para- bellefontia and more strongly furrowed representatives of Bellefontia, such as B. chamberlaini Clark (Hintze 1953, P1.4, figs. 11 -13): effacement is restricted to the cranidial and, to a lesser extent, pygidial axial furrows; cephalic and pygidial borders are well defined. ...
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... P1. 26, figs. 1-3, 7, 9, 10, 12, and 13;Westrop 1986b, P1.32, figs. 9, 10, and 12, P1. 33, figs. 11 -13) is a very narrow rim that is different from those of species of Bellefontia. In addition, the pleural fields of pygidia of Symphysurina are evenly downsloping and lack borders (e.g., Fortey 1983, P1. 27, figs. 3 and 4; Westrop 1986b, P1. 32, fig. ...
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... gyracantha (Raymond, 19 10 fig. 10. 1954 Symphysurus convexus, Fisher, P1. 4, fig. 8 (only). ?I983 Parabellafontia? sp.indet., Stitt, p. 19, P1. 3, fig. ...
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... pygidium from the Tribes Hill Formation, Fort Hunter, New York, illustrated by Cleland (1900, P1. 16, fig. ...
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... meraspid and holaspid ontogeny involves significant changes in cranidial proportions ( Fig. 9): (1) Relative size of palpebral lobes decreases during late meraspid to holaspid cranidial ontogeny from about 45 to 25% of cranidial length (Fig. 10A); relative length of prepalpebral portion of cranidium increases (Fig. 9). (2) In small individuals, width across pal- pebral lobes exceeds maximum width of prepalpebral portion of cranidium. This relationship becomes reversed in larger specimens (Fig. ...
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... late meraspid to holaspid cranidial ontogeny from about 45 to 25% of cranidial length (Fig. 10A); relative length of prepalpebral portion of cranidium increases (Fig. 9). (2) In small individuals, width across pal- pebral lobes exceeds maximum width of prepalpebral portion of cranidium. This relationship becomes reversed in larger specimens (Fig. ...
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... is semicircular in outline, with length equal to slightly more than half of width ( Fig. 1 lA), and lacks a margi- nal spine throughout meraspid and holaspid ontogeny. Promi- nent articulating facet and deep pleural furrow present at anterior. ...
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... is semicircular in outline, with length equal to slightly more than half of width ( Fig. 1 lA), and lacks a margi- nal spine throughout meraspid and holaspid ontogeny. Promi- nent articulating facet and deep pleural furrow present at anterior. Axis occupies about four-fifths of pygidial length (Fig. 11B) For personal use only. surfaces. Ill-defined, roughly transverse pleural bands separated by very shallow pleural furrows may be present on parietal sur- faces. Border is gently concave and occupies about one-fifth of pygidial length. Inner margin of pygidial doublure forms smooth curve that is interrupted by short embayment beneath ...
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... previous work (Raymond 19 10; Fisher 1954), this species was assigned to the genus Asaphellus Callaway. However, the recent reevaluation of the type species of Asaphellus, A. homfreyi (Salter), by Fortey and Owens (1991, figs. 31-3u, 7a-7g, 8a, and 8b) indicates that there are few similarities with B. gyracantha other than effacement. Asaphellus homfreyi differs by possessing smaller, more anteriorly positioned pal- pebral lobes and, consequently, much longer (exsag.) posterior fixed cheeks. The facial sutures of A. holmfreyi proceed back- wards along a curved course, ...
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... The median glabellar tubercle of A. homfreyi is located well behind the level of the palpebral lobes but lies between the palpebral lobes in B. gyracantha (Pl. 2 , figs. 1 and 3). Finally, the hypostome of B. gyracantha is subrectangular with narrow borders (Pl. ...
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... 2 , figs. 1 and 3). Finally, the hypostome of B. gyracantha is subrectangular with narrow borders (Pl. 2, fig. 8), whereas that of A. homfreyi is elliptical in outline and has broad borders (Fortey and Owens 1991, fig. 7 f ) . Boyce (1989) anteriorly, long palpebral lobes, and a broadly based genal spine (Boyce 1989, P1. 36, figs. 5-9, P1. 38, figs. 1-3) which, although not characteristic of Bellefontia, are matched in bath- yurellines such as Uromystrum (Boyce 1989, P1. 33, figs. 710). Pygidia attributed to Uromystrum (see Boyce 1989, P1. 34, fig. 5) compare favourably to those of Randaynia (Boyce 1989, P1. 37, figs. 1 -10, P1. 38, figs. 8 -1 I), differing only in their greater ...
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... axial furrows on testate surfaces, even in small individuals, separates B. gyracantha from all other members of the genus except Bellefontia cocinna (Hintze 1953, PI. 3, figs. 1-8). However, this species lacks an anterior border and the genal spines are lost in large holaspids. Belle- fontia gyracantha also differs from B. franklinense (Ross 195 fig. 12). Diagnosis A species of Hystricurus with a strongly convex, subovoid glabella outlined by deep axial furrows; lateral glabellar furrows are represented only by smooth areas on sides of glabella. Frontal area is subequally divided into gently inflated pre- glabellar field and slightly longer, convex anterior ...
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Citations
... 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.
... 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). ...
... A despeito do vasto e bem estudado documentário fossilífero dos trilobites (Speyer & Brett, 1985Westrop, 1986Westrop, , 1992Speyer, 1987Speyer, , 1991Mikulic, 1990;Westrop et al., 1993;Westrop & Rudkin, 1999;Brett et al., 2012), o registro fóssil dos artrópodes, em geral, e dos crustáceos, em particular, é incompleto e enviesado (Plotnick & McCarroll, 1989). Este fato está relacionado à rápida decomposição da cutícula (Allison, 1986;Plotnick, 1986Plotnick, , 1990Poulicek et al., 1988;Plotnick & McCarroll, 1989;Martin, 1999;Stempien, 2005). ...
... Os dados obtidos foram então combinados com os de literatura (Beurlen, 1953;Brooks, 1962;Mezzalira, 1971;Pinto, 1971;Pinto & Adami-Rodrigues, 1996;Taylor et al., 1998;Hotton et al., 2002;Piñeiro et al., 2012a, b), permitindo compreender melhor a tafonomia básica e o espectro das diferentes condições de preservação dos pigocefalomorfos. Os estados de preservação identifi cados foram comparados e/ou correlacionados aos conhecidos para a tafonomia dos trilobites (Speyer & Brett, 1985Westrop, 1986Westrop, , 1992Speyer, 1987Speyer, , 1991Mikulic, 1990;Westrop et al., 1993;Westrop & Rudkin, 1999), possibilitando o estabelecimento de um modelo próprio de preservação para os pigocefalomorfos. ...
... Porém, as carapaças mostram distribuição polimodal, indicando que não houve seleção por tamanho. Portanto, os fl uxos não foram persistentes o sufi ciente para selecionar o material bioclástico (veja exemplos semelhantes para trilobites em Westrop, 1986Westrop, , 1992Mikulic, 1990;Westrop et al., 1993;Westrop & Rudkin, 1999). As carapaças e os diminutos fragmentos devem ter sido transportados por correntes densas (hiperpicnais) e decantados sob a ação de fl uxos oscilatórios induzidos pelas tempestades (M. ...
Crustaceans (Pygocephalomorpha, Peracarida) are the main fossil invertebrates recorded in the Early Permian Assistência Formation, Irati Subgroup, State of São Paulo, Paraná Basin. For this study, samples taken from the base of the Ipeúna Member, Bairrinho Bed, State of São Paulo, were analyzed and complemented by fossils from the Irati Formation, State of Rio Grande do Sul. The taphonomic spectrum of the pygocephalomorphs includes three main preservational modes: Type 1. Complete pygocephalomorphs (with outstretched or fl exed abdomen), which are associated to cream-colored mudstones and more commonly to black shales. In rare cases, molds of soft parts are preserved. They suffered rapid burial (hours to days) by mud blankets associated to storm events in anoxic bottoms, below storm wave base with minimum bottom disruption, followed by low rates of background sedimentation; Type 2. Partly articulated (carapace and abdomen, with or without caudal fan and without appendages) pygocephalomorphs, with extended or fl exed abdomen, which are present in cream-colored pelites, associated with hummocky cross-stratifi cations, intercalated with black shales. These may represent individuals or remains lying in the sediment-water interface preserved by rapid burial associated to episodic sedimentation events; Type 3. Disarticulated pygocephalomorphs, with isolated carapaces, abdomen, or abdominal segments. This is the predominant preservational mode in our samples. The skeletal remains can be found isolated or in dense, bioclast-supported concentrations (micro-coquines), representing proximal to distal tempestites. Finally, the extreme preservational quality seen in crustaceans of the Type 1 recorded in black shales, occasionally with molds of soft parts, indicates that the host rocks may represent Konservat-Lagerstätten deposits, as already suggested to coeval occurrences of the Irati Formation in Uruguay.
... The Laurentian genus Clelandia Cossmann 1902 is comparable to Elaphraella? taebaeksanensis in having a highly sinuous facial suture and a conical glabella, albeit Clelandia is upper Sunwaptan to lower Ibexian (see Westrop et al., 1993) in age, hence younger than Elaphraella? taebaeksanensis. ...
... taebaeksanensis. Westrop et al. (1993) suggested that Clelandia differs from shumardiids in having a marked inflexion of facial suture and a conspicuous anterior cranidial arch. These features are now shown by the primitive shumardiid Elaphraella? ...
The trilobite family Shumardiidae is characterized by small size, lack of eyes, yoked librigenae, and a small number of thoracic segments. Here we report the successive occurrence of three middle Furongian shumardiid species from the Sesong Formation of Korea: Elaphraellal taebaeksanensis n. sp., Elaphraella microforma, and Elaphraella nodus. They appear to represent the oldest shumardiid morphology known so far. This genus lacks the anterolateral swellings on the glabella and has a conical glabella. Its yoked librigenae also encompass a comparatively wide genal field. Elaphraellal taebaeksanensis has a highly inflexed facial suture which may reflect the presence of small palpebral lobes. Taken together, the plesiomorphic morphology of the Shumardiidae can be summarized as having a conical glabella, small palpebral lobes, highly arched anterior cephalic margin, a wide librigenal field, and no anterolateral swellings on the glabella.
... Bellefontia gyracantha (Raymond, 1910)?,"Hystricu- rus" ellipticus (Cleland, 1900) and Symphysurina myopia Westrop in Landing et al., 2003 indicate a correlation with the Tribes Hill Formation and equivalents of New York State, USA (Cleland, 1900(Cleland, , 1903Fisher, 1954;Flower, 1968;Fisher and Mazzulo, 1976;Westrop et al., 1993;Landing et al., 1996Landing et al., , 2003. There, they are grouped in the Clelandia parabola fauna and are correlated with the Belle- fontia franklinense subzone of the McKenzie Hill Formation of Oklahoma (Stitt, 1983;Westrop et al., 1993). ...
... Bellefontia gyracantha (Raymond, 1910)?,"Hystricu- rus" ellipticus (Cleland, 1900) and Symphysurina myopia Westrop in Landing et al., 2003 indicate a correlation with the Tribes Hill Formation and equivalents of New York State, USA (Cleland, 1900(Cleland, , 1903Fisher, 1954;Flower, 1968;Fisher and Mazzulo, 1976;Westrop et al., 1993;Landing et al., 1996Landing et al., , 2003. There, they are grouped in the Clelandia parabola fauna and are correlated with the Belle- fontia franklinense subzone of the McKenzie Hill Formation of Oklahoma (Stitt, 1983;Westrop et al., 1993). ...
... According to Fisher (1954), Bellefontia gyracantha (Raymond, 1910) occurs in his Fort Johnson, Palatine Bridge, Wolf Hollow and Fonda members of the Tribes Hill Formation, whereas "Hystricurus" ellipticus (Cleland, 1900) is restricted to the Fonda member. Westrop et al. (1993Westrop et al. ( , page 1618) found Fisher's members "difficult to apply consistently in the field" and treated the Tribes Hill Formation as an undivided disconformity-bounded unit between the underlying Little Falls Dolomite (Cambrian) and the overlying Middle Ordovician Black River or Tren- ton groups. Consequently, Landing et al. (1996) proposed a new internal stratigraphy for the Tribes Hill Formation: the Sprakers Member (new), Van Wie Member (new), Wolf Hollow Member (revised) and Canyon Road Member. ...
The lithostratigraphy of the Tremadocian Watts Bight Formation (St. George Group) is best known in the Isthmus Bay section where it includes superb microbial mound complexes and is part of a Skullrockian transgressive–regressive sequence that also includes rocks of the lower Boat Harbour Formation. Twenty kilometres to the west, however, the mounds are no longer dominant although still sporadic near the base. The succession there, instead, consists of monotonous, thickly bedded, sty-lonodular lime mudstone and wackestone with frequent thin sheets and lenses of grainstone and rudstone. The facies support a more open, subtidal shelf setting in the west of the peninsula, deposited during the basal transgressive stage of the sequence, likely correlating with the Stonehenge transgression defined in the central Appalachians.
... On the outer shelf in Dutchess County, southern New York, the member is an anoxic black mudstone . To the west and north on the craton in New York, it is a fossiliferous grey shale (Westrop et al., 1993;Landing et al., , 2003. The anoxic-oxic Van Wie was a shallow-water deposit as peritidal limestone with mollusks underlies it; wave-rippled carbonate storm beds occur at its base, middle, and top; and shallow-water limestone with thrombolites and mollusks overlie it (Landing et al., in press). ...
The Early Paleozoic featured nine intervals of strong expansion of an upper slope, dysoxic/anoxic (d/a) water mass with eustatic rise or epeirogenic transgression. Strong expansion of this d/a water mass led to deposition of time-specific, macroscale alternations of dark grey-black mudstone within oxic, green to red mudstone on the middle–lower slope. This d/a facies even onlapped warm- (carbonate) and cool-water (siliciclastic) shelves. As in the Mesozoic, d/a muds were deposited in shallow water, perhaps tens of metres deep, with sea-level rise. These nine d/a macroscale alternations correspond to intervals of “global hyperwarming”—times of very intense greenhouse conditions that resulted from a feedback initiated by higher insolation and heat storage as shallow seas onlap tropical palaeocontinents. Warm epeiric seas heated the ocean, and thermal expansion accelerated eustatic rise. Ever more extensive epeiric seas heightened oceanic and global temperature as heat storage capacity increased. Deep ocean circulation intensity fell below that of a greenhouse interval and lead to d/a deposition low on the slope and on the platforms to provide the signature of global hyperwarming. Global hyperwarming differs from a hothouse interval as it does not require CO2 input from large igneous provinces to produce high temperatures and never shows deep-sea anoxia. Late Ordovician and Late Devonian black mudstones that cover much of Laurentia record epeirogenic transgressions that led to global hyperwarming, and suggest that cold water upwelling or plant terrestrialisation had nothing to do with epeiric sea anoxia. Global hyperwarming reduced oxygen solubility in these seas, and erosion of orogens produced muddy water that limited light penetration and promoted shallow-water anoxia. The global hyperwarming hypothesis means that relative eustatic and epeirogenic sea levels complement the effect of global pCO2 on climate, and sea level must also be regarded as a primary driver of Phanerozoic climate.
... This early interest in the Lower Paleozoic of eastern Laurentia lapsed, and subsequent work was largely limited to Flower's (1964aFlower's ( , 1968 description of predominantly new cephalopod taxa which were based on a limited number of specimens from New York that he had taken to New Mexico. Fortunately, Flower's large collections, as well as those made earlier by W. B. Dwight, R. Ruedemann and H. P. Cushing, remain in the New York State Museum (NYSM) Paleontology Collection, and were used to evaluate the taxonomy and diversity of Laurentian cephalopods , 2008Landing and Kröger, 2009) and trilobites (Westrop et al., 1993;Brett and Westrop, 1996;Landing et al., 2003;Landing and Westrop, 2006). The conodont fauna of the Tribes Hill Formation and parts of the Rochdale and Fort Cassin Formation of New York and Vermont was described by Landing et al. (1996Landing et al. ( , 2003 and Landing and Westrop (2006) and allowed for a progressive revision of the stratigraphic framework. ...
... This long and episodically intense history of research on the fauna and stratigraphy of the Beekmantown Group includes quantitative fossil occurrence data with high stratigraphic control (particularly trilobites: Westrop et al., 1993;Brett and Westrop, 1996;conodonts: Landing et al., 1996, 2007, cephalopods: Kröger and Landing, 2007, 2008. Herein, we review the current knowledge on the sedimentology, paleontology and stratigraphy of these Lower Ordovician macroscale depositional cycles with the intention of developing a detailed understanding of the ecosystem changes in this time interval. ...
... The trilobite faunas of the thrombolitic limestones contrast with those of the underlying and overlying units. In the Tribes Hill Formation Westrop et al. (1993), and Landing et al. (2003) distinguished between a "Bellefontia Biofacies" in subtidal shales with bioclastic interbeds, and a "gastropod-rostroconch Biofacies" with a Clelandia parabola fauna in bioclastic limestones, which contrast with the Symphysurina-dominated fauna in the thrombolitic limestones. A comparable trilobite biofacies differentiation exists in the St. George Group of Newfoundland, in which the thrombolite limestones contain an Illaenus-Bolbocephalus biofacies which differs from a bathyuroid biofacies in the non-buildup environments (Boyce et al., 2000). ...
The Beekmantown Group records the important early interval of the Ordovician Radiation. This Upper Cambrian–Middle Ordovician, carbonate-dominated, tropical succession was deposited near the eastern passive margin of the Laurentian platform. This depositional setting remained remarkably stable although the craton was flooded repeatedly with eustatic rises and unconformity-bound, macroscale sedimentary cycles were deposited as successive geological formations. The individual depositional cycles (i.e., formations) show a nearly identical vertical succession with a type 1 sequence boundary, a basal conglomerate, transgressive sandstones, locally a subtidal shale-dominated unit that marks the deepest facies, and a highstand carbonate facies with thrombolite buildups in its middle part. The thrombolitic buildups of each depositional cycle contain a mollusc-dominated macrofauna that changed remarkably from cycle to cycle. In the limestones of the Upper Cambrian Ritchie and Rathbunville School members, the macrofauna is very rare and of low diversity. By comparison, the absolute abundance of macrofossils is high throughout the Lower Ordovician thrombolitic limestones. The genus-level diversity of brachiopods, trilobites, gastropods, and cephalopods increased moderately during the three Lower Ordovician depositional sequences. Dramatic changes in cephalopod disparity, body size, and biomass indicate significant paleoecological changes at the top of the ecosystem food chains, and are an indication of community evolution and intrinsic evolutionary processes. Increased coiling and ornamentation in cephalopods and an increasing number of large gastropod genera with thick shells indicate an escalation among predators. We interpret these changes as evidence for a rise in competition within ecological guilds by a continuing increase in internal differentiation of the food web. Increased organismal interaction and the differentiation of the food web (i.e., community evolution) are regarded as a major driving mechanism early in the Ordovician Radiation. © 2009 Published by Elsevier B.V.
... 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. ...
... 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.
... In contrast to previous studies of Paleozoic community evolution (Sepkoski and Sheehan, 1983; Sepkoski and Miller, 1985; Sepkoski, 1991), this analysis is conducted at the species level, rather than at higher taxonomic levels. It is based largely on our own systematic work (Tremblay and Westrop, 1991; Westrop, 1992; Westrop et al., 1993 ; Westrop and Landing, unpublished data). RESULTS All of the nearshore sequences studied here contain well-defined trilobite biofacies (Ludvigsen and Westrop, 1983; Tremblay and Westrop, 1991; Westrop, 1992; Westrop et al., 1993 ; Westrop and Landing, unpublished data). ...
... It is based largely on our own systematic work (Tremblay and Westrop, 1991; Westrop, 1992; Westrop et al., 1993 ; Westrop and Landing, unpublished data). RESULTS All of the nearshore sequences studied here contain well-defined trilobite biofacies (Ludvigsen and Westrop, 1983; Tremblay and Westrop, 1991; Westrop, 1992; Westrop et al., 1993 ; Westrop and Landing, unpublished data). Although there was considerable turnover at higher taxonomic levels, trilobite species diversity remained essentially unchanged: the mean number of species present hovered around three from the Upper Cambrian through Middle ...
... In the Marjuman samples, trilobites account for two-thirds of the species present, and are associated with inarticulate brachiopods and hyoliths (see also Sepkoski and Miller, 1985). By the Late Sunwaptan to Early Ibexian interval, paleocommunity compositions are split evenly between trilobites and molluscs, with gastropods and rostroconchs representing the molluscan component (see also Sepkoski and Miller, 1985; Westrop et al., 1993 ). Finally, in the Whiterockian-Mohawkian interval, trilobites are joined by various molluscs and other taxa, such as bryozoans, and have become reduced to about one-third of the number of species present. ...
