James E. Starnes’s research while affiliated with Arizona Department of Environmental Quality and other places

Isolated elasmobranch and teleost teeth, jaws, otoliths, scales, vertebrae, and fin spines were recovered from the upper Oligocene (Chattian) Catahoula Formation in Wayne County, Mississippi, USA. A total of 13 551 specimens were examined and 12 340 of these were identified at least to the ordinal level. These remains represent 49 unequivocal fish taxa, viz. 29 elasmobranchs and 20 teleosts. The 3614 elasmobranch remains indicate that Carcharhiniformes is the most diverse group of Elasmobranchii, with 12 taxa belonging to five families. Orectolobiformes and Lamniformes are represented by far fewer taxa (three and four, respectively). Carcharhinus acuarius (Probst, 1879) constitutes 49% of the total number of shark teeth in our sample. Ten batoids have been identified within Myliobatiformes (seven taxa) and Rhinopristiformes (three taxa). Partial teeth of durophagous myliobatids (three genera) are the most abundant batoid remains, constituting 41% of the total number of ray fossils. However, teeth of Dasyatidae and Rhynchobatus cf. pristinus (Probst, 1877) are abundant and represent 36.5% and 15.4%, respectively, of the specimens identified. Herein, we erect five new elasmobranch taxa, including Galeocerdo platycuspidatum sp. nov., Hemipristis intermedia sp. nov., Hypanus? heterodontus sp. nov., “Sphyrna” gracile sp. nov., and “Sphyrna” robustum sp. nov. The Catahoula Formation sample includes over 9935 teleost fossils, which constitutes 73% of the total fish sample. Nine bony fish taxa are represented solely by teeth, jaw elements, or fin spines. Although otoliths are much less common than the other identifiable remains (409 versus roughly 8430, respectively), they allowed us to identify four taxa not known from other skeletal remains. Albulidae, Sciaenidae, and Sparidae are represented by isolated teeth, jaw elements, and otoliths, but we could not ascertain whether the various teeth and jaw elements are conspecific with the otolith-based species we identified. The remains of Sciaenidae (teeth, jaw elements, otoliths) dominate the Catahoula Formation bony fish assemblage, constituting 70% of the teleost specimens identified at least to the ordinal level. Our sample includes the first Oligocene occurrence of Tetraodontidae in the Western Hemisphere. The vertebrate assemblage within the Catahoula Formation at the study site indicates an estuarine depositional environment, which is consistent with previous interpretations based on lithology. At the study site the Catahoula Formation disconformably overlies the Paynes Hammock Limestone, and we believe the disconformable contact locally represents the Rupelian (early Oligocene)/Chattian (late Oligocene) boundary. The fish fauna described herein is therefore of Chattian age.

Situated throughout the southeastern United States within the Laurentian craton are occurrences of various aged deposits (Late Proterozoic to Early Paleogene) that contain volcanics spanning from lamprophyres to carbonatites and basalts to rhyolites. Several are intrusive, while others have been reworked detritally, deposited as river gravels out onto the Gulf Coastal Plain. The earliest occurrence of igneous gravel clasts in the coastal plain of the lower Mississippi Valley lie along the Mississippi River’s eastern valley wall in the ancestral Mississippi River’s pre-loess terrace deposits (PLTDs). The coarse clastics of the PLTDs are dominantly chert gravels derived from Paleozoic carbonate bedrock, but also include clasts of Precambrian Sioux Quartzite, glacially faceted and striated stones, and ice-rafted boulders, which indicate a direct relationship between the PLTDs and glacial outwash during the cyclic glaciation of the Pleistocene Epoch. The PLTDs also contain the oldest known examples of igneous gravels exposed at the surface in Mississippi. An understanding of their igneous bedrock provenance and the timing of their contribution to the sedimentary record of the lower Mississippi River Valley sheds a valuable light onto the geologic history and evolution of the ancestral Mississippi River during the Pleistocene Epoch. The use of fusion inductively coupled plasma mass-spectroscopy (ICP-MS) in the identification of the igneous suites of one of the pre-loess terraces, well-delineated by geologic mapping, adds important geochemical source data from the gravel constituents for the further interpretation and correlation of the individual PLTD allounits. Gravel constituent geochemistry also offers a better understanding of the evolution of the ancestral Mississippi River watershed and the contributions of bedrock sources during Pleistocene glaciation. This petrological study suggests that the igneous gravels sampled from within the Rawhide PLTD allounit originated from the St. Francois Mountains (SFMs) in southwestern Missouri, with the implications that the SFM igneous terrain was in the direct path of the Independence “Kansan” glaciation. This could indicate a glacial extent further southwest than previously documented.

The specimens for this investigation were recovered from the only Pliocene locality in the Gulf Coastal Plain known to contain otoliths. A previous study of otoliths from this site was based on a meager 250 specimens and 22 bony fish taxa were identified. The present investigation, which was based on an additional 3,840 otoliths, revealed 12 more taxa and allowed two previously documented taxa to be definitively assigned to species. The additional taxa resulted in an otolith assemblage of 34 taxa and provided further, more detailed information on the paleoenvironmental setting. Within species diversity, the number of otolith-based taxa (34) indicates a moderately high richness. However, the relative abundance of each species present (evenness) is very low with one species (Micropogonias undulatus) representing 82.98% of the total number of specimens. Sciaenidae represent an astounding 96.45% of the total number of specimens. The abundance of the sciaenid M. undulatus (3,394 specimens) was especially significant for paleoecological determinations and indicated that 99.18% of the otoliths represented fish less than one-year-old (i.e., juveniles). This preponderance of M. undulatus sagittae pointed to shallow, soft-bottom estuarine creeks and bays and possibly upstream oligohaline creeks and strongly suggests a primary nursery area for the species. The analysis of the other taxa indicates a more open estuary near a shallow marine environment also existed.

This research concerns plant microfossils and megafossils from the Forest Hill Formation in Smith County.

The first Pliocene teleostean otoliths from the Gulf Coastal Plain are described from Dauphin Island, Mobile County, Alabama, USA. The 250 otolith specimens, mainly sagittae, were obtained from shell hash dredged from an offshore Pliocene unit deposited onshore as part of recent beach nourishment. Analysis of the otoliths revealed 22 species from 11 teleostean families. Sciaenid fishes dominate the assemblage and account for 79.6% of the total specimens, while the other 10 families (including indeterminates) comprise approximately 20% of the total. Comparison to modern biological and ecological requirements for the fishes represented by the otoliths suggest a shallow (0–20 m) neritic environment with some brackish and rare deep-water influence. Several of the most abundant taxa indicate shallow, soft bottom estuarine habitat with upstream oligohaline creeks (0.5 to 5.0 ppt salinity) serving as primary nursery area. However, the percentage of marine-only species may indicate more interaction with open estuary and shallow coastal areas and subtropical waters. The lack of invertebrate settlement on the otoliths likely indicates limited surface residence-time. All 22 taxa recovered from the Dauphin Island site are highly significant since they represent the first Pliocene occurrences of these taxa within the Gulf Coastal Plain of North America.

A Rangia johnsoni bed in the late Miocene Pascagoula Formation was encountered in three test holes drilled during the 2016-2017 United States Geological Survey STATEMAP geologic mapping project field work in Stone and George counties in southeastern Mississippi. Teleostean otoliths were recovered from drill samples in a R. johnsoni shell bed in a dark, carbonaceous clay at a depth of 103.6-106.7 m below land surface in Stone County (Test D-0057; 30.836452N, 088.915771W). The otoliths are well preserved and were identified as Micropogonias undulatus (Atlantic croaker) based on comparisons to Recent Gulf of Mexico otoliths. All otoliths were less than 5.54 mm in length and represented fish less than 90 mm in length. Since modern one-year-old M. undulatus are generally greater than 201 mm length, the otoliths represented juvenile fish (< 1 year). Modern juvenile M. undulatus reside for several months in oligohaline primary nursery areas, which consist of shallow upstream, organic-rich, soft-bottom estuarine creeks and bays. Analysis of the fossil otoliths is highly significant as it represents the first Miocene otoliths described from Mississippi and the central Gulf Coast and is the oldest occurrence of Micropogonias undulatus. The otoliths from the drill sample also provide valuable insight into the highly debated depositional environment of the R. johnsoni beds of the Pascagoula Formation in southeastern Mississippi. Additionally , otoliths from cores and well cuttings are essentially undescribed in the Gulf Coast and warrant study.