396


Journal of Paleontology 92(3):388–397


for the Moscow Formation could explain the significant differ- ence between Moscow and Skaneateles samples. Additionally, the results of the CVA analysis showed no clear separation among the stratigraphic groups (Fig. 6). In summary, although differences can statistically be detected, these are limited to individual PC axes that do not amount to great overall differ- ences. However, more data are needed to conclusively exclude or confirm phyletic change during this time period. The Moscow sample exhibits a high degree of morpho-


logical variability within the sample. Modern organisms have been observed to respond to environmental perturbation by an increase of phenotypic plasticity (e.g., Hoffmann and Parsons, 1997; Hoffmann and Hercus, 2000; Chevin et al., 2013). The reduction of suitable habitat, due to a major regression and the associated loss of habitable shelf area at the boundary of the Ludlowville and Moscow formations (Brett et al., 2007b, 2010; Ellwood et al., 2011) might represent such a disturbance, causing the increased morphological variability observed in the Moscow sample. Our data show that specimens from the muddy facies


generally develop broader and more circular shell disks with a longer posterior sulcus than samples from other facies. These morphologies suggest a link to environmental factors. Actinopteria boydi’s life habit was thoroughly discussed by Johnston (1993) and has been interpreted as epifaunal and byssally attached to objects on the sea floor. Our data show that the location of the byssus at the ventral margin of the anterior auricle remains stable in relation to the rest of the shell (Fig. 4), suggesting that the low-angled epifaunal life position with the slightly inclined commissure of A. boydi remained more or less unchanged throughout the time interval. Johnston (1993) demonstrated experimentally that morphologically similar taxa, such as the extant Pinctada sugillata (Reeve, 1857), utilize the shape of their posterior wing to channel water via the sulcus to the posterior inhalant siphon. Low pressure created by the water current enhances water intake by passive ventilation, resulting in lower energy expenditure during feeding. The broader shell disk of the mud morph might have maximized the flow velocity along the shell and in combination with a long posterior sulcus improved flow rates of water channeled over the posterior shell portion that is especially beneficial in environments with low water energy. Overall, our data show no significant shift in disk mor-


phology of Actinopteria boydi through ~3–4 Myr. We could not observe any group that was distinct enough to warrant separa- tion of a distinct taxon in this time interval, hence, we conclude that the A. boydi lineage was in evolutionary stasis and that the observed differences are ecophenotypic variation of a single taxon in response to environmental conditions.


Acknowledgments


We would like to thank St. Lawrence University for partial funding of this project through the M.J. Erickson Geology University Fellows Endowment, and the Paleontological Research Institution in Ithaca for granting us access to their collections. We also thank M. TenEyck, SUNY Cortland, for assisting with photography of specimens.


References


Amler, M.R.W., 1995, Die Bivalvenfauna des Oberen Famenniums West- Europas. 1. Einführung, Lithostratigraphie, Faunenübersicht, Systematik 1. Pteriomorphia: Geologica et Palaeontologica, v. 29, p. 19–143.


Bailey, J.B., 1983, Middle Devonian Bivalvia from the Solsville Member (Marcellus Formation), central New York State: American Museum of Natural History Bulletin, v. 174, p. 193–326.


Bassler, R.S., 1915, Bibliographic index of American Ordovician and Silurian fossils: Bulletin of theUnited StatesNationalMuseum, v. 92, no. 1, p. 1–1521.


Batt, R.J., 1996, Faunal and lithologic evidence for small-scale cyclicity in the Wanakah Shale (Middle Devonian) of western New York: Palaios, v. 11, p. 230–243.


Bookstein, F.L., 1991, Morphometric Tools for Landmark Data: Geometry and Biology: New York, Cambridge University Press, 435 p.


Brett, C.E., ed., 1986, Dynamic Stratigraphy and depositional environments of the Hamilton Group (Middle Devonian) in New York State, Part I: New York State Museum Bulletin, v. 457, no. 156, p. 324–327.


Brett, C.E., 2012, Coordinated stasis reconsidered:Aperspective at fifteen years, in Talent, J.A., ed., Earth and Life, Global Biodiversity, Extinction Intervals and Biogeographic Perturbations Through Time: Amsterdam, Springer, p. 23–36. doi: 10.1007/978-90-481-3428-1_2.


Brett, C.E., and Baird, G.C., 1985, Carbonate-shale cycles in the Middle Devonian of New York: An evaluation of models for the origin of lime- stones in terrigenous shelf sequences: Geology, v. 13, p. 324–327.


Brett, C.E., and Baird, G.C., 1995, Coordinated stasis and evolutionary ecology of Silurian to Middle Devonian faunas in the Appalachian Basin, in Erwin, D.H., and Anstey, R.L., eds., New Approaches to Speciation in the Fossil Record: New York, Columbia University Press, p. 285–315.


Brett, C.E., and Baird, G.C., 1996, Paleontological Events: Stratigraphic, Eco- logical and Evolutionary Implications: New York, Columbia University Press, 616 p.


Brett, C.E., Bartholomew, A.J., and Baird, G.C., 2007a, Biofacies recurrence in the Middle Devonian of New York State: An example with implications for evolutionary paleoecology: Palaios, v. 22, p. 306–324. doi: 10.2110/ palo.2005.p05-027r.


Brett, C.E., Hendy, A.J.W., Bartholomew, A.J., Bonelli, J.R., and McLaughlin, P.I., 2007b, Response of shallow marine biotas to sea-level fluctuations: A review of faunal replacement and the process of habitat tracking: Palaios, v. 22, p. 228–244. doi: 10.2110/palo.2005.p05-028r.


Brett, C.E., Ivany, L.C., Bartholomew, A.J., DeSantis, M.K., and Baird, G.C., 2009, Devonian ecological-evolutionary subunits in the Appalachian Basin: A revision and a test of persistence and discreteness: Geological Society Special Publication, v. 314, p. 7–36. doi: 10.1144/SP314.2.


Brett, C.E., Baird, G.C., Bartholomew, A.J., DeSantis, M.K., and Ver Straeten, C.A., 2010, Sequence stratigraphy and a revised sea-level curve for the Middle Devonian of eastern North America: Palaeogeography, Palaeocli- matology, Palaeoecology, v. 304, 21–53. doi: 10.1016/j.palaeo.2010. 10.009.


Carter, J. G., ed., 1990, Skeletal Biomineralization: Patterns, Processes and Evolutionary Trends, v. 2 Volumes: New York, Van Nostrand Reinhold, 832 + 101 p.


Carter, J.G., and Tevesz, M.J.S., 1978, Shell microstructure of a Middle Devo- nian (Hamilton Group) bivalve fauna from central New York: Journal of Paleontology, v. 52, no. 4, p. 859–880.


Chevin, L., Collins, S., and Lefèvre, F., 2013, Phenotypic plasticity and evolu- tionary demographic responses to climate change: Taking theory out to the field: Functional Ecology, v. 27, p. 967–979. doi: 10.1111/j.1365- 2435.2012.02043.x.


Conrad, T.A., 1842, Fifth annual report on the paleontology of the State of New York: New York Geological Survey Annual Report, v. 5, p. 25–57.


Cooper, G.A., 1929, Stratigraphy of the Hamilton Group of New York: American Journal of Science, v. 110, p. 116–134.


Cooper, G.A., 1935, Stratigraphy of the Hamilton Group, eastern New York: American Journal of Science, v. 157, p. 1–12.


Cox, L.R., Newell, N.D., Boyd, D.W., Branson, C.C., Casey, R., Chavan, A., Coogan, A.H., Dechaseux, C., Fleming, C.A., Haas, F., Hertlein, L.G., Kauffman, A., Keen, M.A., LaRocque, A., McAlaster, A.L., Moore, R.C., Nuttall, C.P., Perkins, B.F., Puri, H.S., Smith, L.A., Soot-Ryen, T., Stenzel, H.B., Trueman, E.R., Turner, R.D., and Weir, J., 1969, Bivalvia, in Moore, R.C., ed., Treatise on Invertebrate Paleontology, Part N, Mollusca 6: Boulder, Colorado, and Lawrence, Kansas, Geological Society of America (and University of Kansas Press), 1224 p.


Cruz, R.A.L., Pante, M.J.R., and Rohlf, F.J., 2012, Geometric morphometric analysis of shell shape variation in Conus (Gastropoda: Conidae): Zoo- logical Journal of the Linnean Society, v. 165, p. 296–310. doi: 10.1111/ j.1096-3642.2011.00806.x.


Dietl, G.P., 2013, The great opportunity to view stasis with an ecological lens: Palaeontology, v. 56, p. 1239–1245. doi: 10.1111/pala.12059.


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53  |  Page 54  |  Page 55  |  Page 56  |  Page 57  |  Page 58  |  Page 59  |  Page 60  |  Page 61  |  Page 62  |  Page 63  |  Page 64  |  Page 65  |  Page 66  |  Page 67  |  Page 68  |  Page 69  |  Page 70  |  Page 71  |  Page 72  |  Page 73  |  Page 74  |  Page 75  |  Page 76  |  Page 77  |  Page 78  |  Page 79  |  Page 80  |  Page 81  |  Page 82  |  Page 83  |  Page 84  |  Page 85  |  Page 86  |  Page 87  |  Page 88  |  Page 89  |  Page 90  |  Page 91  |  Page 92  |  Page 93  |  Page 94  |  Page 95  |  Page 96  |  Page 97  |  Page 98  |  Page 99  |  Page 100  |  Page 101  |  Page 102  |  Page 103  |  Page 104  |  Page 105  |  Page 106  |  Page 107  |  Page 108  |  Page 109  |  Page 110  |  Page 111  |  Page 112  |  Page 113  |  Page 114  |  Page 115  |  Page 116  |  Page 117  |  Page 118  |  Page 119  |  Page 120  |  Page 121  |  Page 122  |  Page 123  |  Page 124  |  Page 125  |  Page 126  |  Page 127  |  Page 128  |  Page 129  |  Page 130  |  Page 131  |  Page 132  |  Page 133  |  Page 134  |  Page 135  |  Page 136  |  Page 137  |  Page 138  |  Page 139  |  Page 140  |  Page 141  |  Page 142  |  Page 143  |  Page 144  |  Page 145  |  Page 146  |  Page 147  |  Page 148  |  Page 149  |  Page 150  |  Page 151  |  Page 152  |  Page 153  |  Page 154  |  Page 155  |  Page 156  |  Page 157  |  Page 158  |  Page 159  |  Page 160  |  Page 161  |  Page 162  |  Page 163  |  Page 164  |  Page 165  |  Page 166  |  Page 167  |  Page 168  |  Page 169  |  Page 170  |  Page 171  |  Page 172  |  Page 173  |  Page 174  |  Page 175  |  Page 176  |  Page 177  |  Page 178  |  Page 179  |  Page 180  |  Page 181  |  Page 182  |  Page 183  |  Page 184  |  Page 185  |  Page 186  |  Page 187  |  Page 188  |  Page 189  |  Page 190  |  Page 191  |  Page 192  |  Page 193  |  Page 194  |  Page 195  |  Page 196  |  Page 197  |  Page 198  |  Page 199  |  Page 200  |  Page 201  |  Page 202  |  Page 203  |  Page 204  |  Page 205  |  Page 206  |  Page 207  |  Page 208  |  Page 209  |  Page 210  |  Page 211  |  Page 212  |  Page 213  |  Page 214  |  Page 215  |  Page 216  |  Page 217  |  Page 218  |  Page 219  |  Page 220