Robert F. Lundin

Confocal microscopy: Potential applications in micropaleontology

Preliminary experiments with a confocal microscope (Sarastro 2000®) demonstrate its value in micropaleontology for photography and three-dimensional morphometric studies. High-quality images of objects in the size range of 100 to 2,000 μm can be obtained without application of nonremovable coating. Images can easily be electronically converted to stereopairs or displayed as single images. Images are in focus throughout and are superior to light photographs. Numerical data ( x, y, and z coordinates) in almost any desired amount can be extracted from enough points on the visible surface to provide for the construction of a detailed topographic map of the surface. All of this can be done without manipulating the specimen once it has been mounted.

Freshwater ostracodes from upper Middle Devonian fluvial facies, Catskill Mountains, New York

Leperditiocope ostracodes identified as Sollenella ? sp. were discovered in the Gilboa Formation (upper Givetian, uppermost Middle Devonian) within the continental Catskill Magnafacies of New York State. The deposits in which the ostracodes were found are meandering-fluvial facies that were part of a vast alluvial plain that sloped westward from the eroding Acadian Mountains. Hence, ostracodes colonized freshwater habitats earlier than heretofore thought. It has been widely accepted that, until now, the oldest known unequivocal occurrences of freshwater ostracodes are of Late Carboniferous age. This new discovery means that the first colonization of freshwater habitats by Ostracoda occurred approximately 60 million years earlier than previously known.

Ostracodes from the Naco Formation (Upper Carboniferous) at the Kohl Ranch locality, central Arizona

The Kohl Ranch locality in the Naco Formation (Upper Carboniferous, Desmoinesian) of central Arizona contains an ostracode fauna of 13 species of which three are left in open nomenclature because of inadequate materials; all of the others have been previously described. This fauna is strongly dominated by Hollinella ( Hollinella ) bassleri (Knight, 1928), Cavellina pulchella Coryell, 1928, Bairdia whitesidei Bradfield, 1935, and Bairdiacypris ( Fabalicypris ) regularis Cooper, 1946. Present in moderate numbers are Amphissites ( Amphikegelites ) roundyi Knight, 1928, Moorities minutus Warthin, 1930, and Healdia simplex Roundy, 1926. Pseudobythocypris tomlinsonella Cooper, 1946, Bairdia hoxbarensis Harlton, 1927, Sulcella sulcata Coryell and Sample, 1932, and species of Oliganisus, Sansabella and Chamishaella are represented by only small numbers of specimens. The dominant and moderately abundant species indicate a shallow, offshore environment of deposition. The known geographical range of all species present in the fauna is extended into central Arizona.

Nonpalaeocope ostracod biostratigraphy of the type Wenlock Series, Silurian, of the Welsh Borderland

Analysis of distribution, diversity and abundance of nonpalaeocope ostracods from the type Wenlock Series demonstrates that a major faunal change occurs around the Sheinwoodian-Homerian Stage boundary and that significant increases in faunal diversity occur at that boundary and in the late Whitwell Chronozone. Low abundance and low diversity in the late Sheinwoodian is interpreted to represent maximum water depth for the type Wenlock Series whereas the high diversity fauna of the late Homerian represents shallowest water conditions for this sequence. Many late Homerian species range into the Lower Elton Formation (early Ludlow) which suggests gradual ecostratigraphic change across the Wenlock-Ludlow boundary. Ancestor-descendant relationships for several lineages in the type Wenlock Series define lineage zones which essentially coincide with assemblage zones based on nonpalaeocope ostracods.

The British Silurian ostracod genus Octonaria Jones, 1887: its revision and phylogeny

The ostracod genus Octonaria Jones, 1887 has been grossly misunderstood because of misleading illustrations of the type-species, O. octoformis Jones, 1887. The type species is considered to be the only member of the genus presently known. All other of the nearly four dozen species and varieties which have been placed in the genus are considered to be junior synonyms of O. octoformis or members of other genera. Octonaria is presently known only from late Wenlock to early Ludlow strata of the Welsh Borderland area. It was probably derived from a “Bairdiocypris” gotlandica – like ancestor and is ancestral to the Late Silurian – Early Devonian North American genus Thlipsorothella Lundin & Petersen, 1974.

Function and Significance of Tubules: Tubulibairdia vs. Microcheilinella

Publisher Summary This chapter presents a comparative study of Tubulibairdia and Microcheilinella . They are morphologically similar. They differ in that the former has tubules in its shell wall and the latter does not. Indeed the type species of Microcheilinellu shows no evidence of special shell microstructures such as tubules or sensillum pores. The tubules in Tubulibairdia and other pachydomellids probably had a sensory function or a function in formation of the cuticle of the ostracode. In any case, tubules open only to the interior of the shell; they do not penetrate to the exterior surface. Tubules occur in pre-adult and adult moult stages of various pachydomellid genera including Tubulibairdia. Tubules are a stable character within species of Tubulibairdia and other pachydomellids. Therefore, they are considered as a diagnostic and taxonomically significant at least at the generic level. Although Microcheilinella and Tubulibairdia are distinct and separate genera, placement of species in these genera should be based upon examination of shell microstructure.

Is Neckajatia an Ancestor of the Platycope Ostracodes

Neckajatia Schallreuter, 1974 and a closely related genus are known from a complex of at least four species from the Silurian of Gotland, Great Britain (where the related genus has been recorded as species of Primitid ), Podolia and the eastern Baltic states of the U. S. S. R. The oldest of these species, N. modesta Neckaja, 1958, occurs in rocks older than the rocks which yield the oldest true platycopes which are from the upper Llandoverian of Gotland and Estonia. Neckajatia and the related genus possess characters which are basic to the definition of the platycope ostracodes, but lack others which are equally fundamental to that definition. The combination of characters, which is a) right-over-left overlap, b) a contact groove along all or most of the free margin of the right valve, c) a relatively long straight hinge with a groove in the right valve hinge, d) poorly-developed straguloid processes, but e) the absence of any well-defined dimorphic characters, suggests Neckajatia and related forms are a primitive stock from which the platycopes evolved. It is suggested that this occurred through reduction of the straight hinge, improvement of the contact groove (holoselenic groove) in the right valve and introduction of a distinctive domiciliar dimorphism. Present knowledge indicates that this occurred during the Llandoverian.

SINOLEPERDITIINI (OSTRACODA) FROM THE LOWER EMSIAN SHANGLUN FORMATION AT THE SHANGLUN VILLAGE, CENTRAL GUANGXI, CHINA

Abstract The Shanglun Formation at the Shanglun locality contains a sinoleperditiine fauna of five species of which two are new [Sinoleperditia (Sinoleperditia) shanglunensis and Paramoelleritia (Paraleperditia) wangchengyuani] and one is left in open nomenclature because of inadequate materials. In this fauna, the ratio of the vertical height of the trailing chevron muscle scar to that of the adductor muscle scar (th:ah ratio) ranges from 0.85 to 0.95 with a mean value of 0.90. On the basis of the sinoleperditiines and a beyrichiid ostracode, the upper part of the Shanglun Formation is correlated with the middle-to-late early Emsian Moding Formation. The sinoleperditiines and microfacies analysis indicates that the sediments bearing the fauna were deposited in a low energy restricted carbonate platform environment.