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Heterochrony and the achievement of the multibrachiate grade in camerate crinoids

Published online by Cambridge University Press:  08 April 2016

Thomas W. Broadhead*
Affiliation:
Department of Geological Sciences, University of Tennessee, Knoxville, Tennessee 37996

Abstract

The multibrachiate grade of organization in camerate crinoids was principally attained through pinnule differentiation: the accelerated development of a proximal pinnule that ultimately became a pinnule-bearing arm. Although pinnule differentiation is not the only means of achieving a multibrachiate organization in modern crinoids, it was the primary mode in producing both dichotomous and exotomous branching patterns in multibrachiate camerates. Whereas most of the proximal branchings, commonly fixed in the cup of camerates, were due to pinnule differentiaton, the first dichotomy and distal dichotomies above the cup apparently developed from direct modification of a brachial plate at the growing tip of the immature crinoid arm.

Type
Articles
Copyright
Copyright © The Paleontological Society 

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References

Literature Cited

Ausich, W. I. 1986. The crinoids of the Al Rose Formation (Lower Ordovician, Inyo County, California, U.S.A.). Alcheringa, in press.CrossRefGoogle Scholar
Breimer, A. 1978. General morphology—recent crinoids. Pp. T9T58. In: Moore, R. C. and Teichert, C., eds. Treatise on Invertebrate Paleontology, T (1). Geol. Soc. Am. and Univ. Kansas Press; Lawrence.Google Scholar
Broadhead, T. W. 1981. Carboniferous camerate crinoid subfamily Dichocrininae. Palaeontographica A. 176:81157.Google Scholar
Broadhead, T. W. 1985. Pinnule differentiation and the homology among arms, ramules and pinnules in Ordovician camerate crinoids. Geol. Soc. Am. Abstr. with Prog. 17(7):532.Google Scholar
Brower, J. C. 1973. Crinoids from the Girardeau Limestone (Ordovidian). Palaeontogr. Am. 7:260499.Google Scholar
Brower, J. C. 1974a. Upper Ordovician xenocrinids (Crinoidea, Camerata) from Scotland. Univ. Kansas Paleontol. Contr. Pap. 67:125.Google Scholar
Brower, J. C. 1974b. Ontogeny of camerate crinoids. Univ. Kansas Paleontol. Contr. Pap. 72:153.Google Scholar
Brower, J. C. 1978. Camerates. Pp. T244T263. In: Moore, R. C. and Teichert, C., eds. Treatise on Invertebrate Paleontology, T (1). Geol. Soc. Am. and Univ. Kansas Press; Lawrence.Google Scholar
Gislén, T. 1924. Echinoderm studies. Zoolog. Bidrag fr. Uppsala 9:1330.Google Scholar
Goldring, W. 1923. The Devonian crinoids of the state of New York. New York State Mus. Mem. 16:1670.Google Scholar
Guensburg, T. E. 1984. Echinodermata of the Middle Ordovician Lebanon Limestone, central Tennessee. Bull. Am. Paleontol. 86:1100.Google Scholar
Haugh, B. N. 1975. Digestive and coelomic systems of Mississippian camerate crinoids. J. Paleontol. 49:472492.Google Scholar
Haugh, B. N. 1979. Late Ordovidian channel-dwelling crinoids from southern Ontario, Canada. Am. Mus. Nat. Hist. Nov. 2665:125.Google Scholar
Kelly, S. M. and Ausich, W. I. 1978. A new Lower Ordovician (Middle Canadian) disparid crinoid from Utah. J. Paleontol. 52:916920.Google Scholar
Kelly, S. M., Frest, T. J., and Strimple, H. L. 1978. Additional information on Simplococrinus persculptus. J. Paleontol. 52:12271232.Google Scholar
Laudon, L. R. 1967. Ontogeny of the Mississippian crinoid Platycrinites bozemanensis (Miller & Gurley), 1897. J. Paleontol. 41:14921497.Google Scholar
McKinney, M. L. 1984. Allometry and heterochrony in an Eocene echinoid lineage: morphological change as a by-product of size selection. Paleobiology. 10:407419.CrossRefGoogle Scholar
McNamara, K. J. 1986. A guide to the nomenclature of heterochrony. J. Paleontol. 60:413.Google Scholar
Meyer, D. L. 1965. Plate growth in some platycrinid crinoids. J. Paleontol. 39:12071209.Google Scholar
Mortensen, T. 1920a. Studies in the Development of Crinoids. Carnegie Inst. Pap. Dept. Mar. Biol. 16:194.Google Scholar
Mortensen, T. 1920b. Notes on some Scandinavian echinoderms, with descriptions of two new ophiuroids. Vid. Medd. Dansk Naturhist. Foren. 72:4579.Google Scholar
Paul, C. R. C. and Smith, A. B. 1984. The early radiation and phylogeny of echinoderms. Biol. Rev. 59:443481.Google Scholar
Ross, R. J. Jr., et al. 1982. The Ordovician System of the United States. Int. Union Geol. Sci. 12:173.Google Scholar
Smith, A. B. 1984. Classification of the Echinodermata. Palaeontology. 27:431459.Google Scholar
Sprinkle, J. 1973. Morphology and Evolution of Blastozoan Echinoderms. Mus. Comp. Zool. Harvard Univ. Spec. Publ. 283 pp.Google Scholar
Sprinkle, J. and Bell, B. M. 1978. Paedomorphosis in edrioasteroid echinoderms. Paleobiology. 4:4248.Google Scholar
Strimple, H. L. and McGinnis, M. R. 1972. A new camerate crinoid from the Al Rose Formation, Lower Ordovician of California. J. Paleontol. 46:7274.Google Scholar
Ubaghs, G. 1978. Skeletal morphology of fossil crinoids. Pp. T58T216. In: Moore, R. C. and Teichert, C., eds. Treatise on Invertebrate Paleontology, T (1). Geol. Soc. Am. and Univ. Kansas Press; Lawrence.Google Scholar
Waters, J. A., Horowitz, A. S., and Macurda, D. B. Jr. 1985. Ontogeny and phylogeny of the Carboniferous blastoid Pentremites. J. Paleontol. 59:701712.Google Scholar