Eric J. Hilton

• Doctor of Philosophy
• Professor (Associate) at Virginia Institute of Marine Science

Ichthyoplankton data sets based on collections from estuaries in South Carolina, North Carolina, Virginia, Delaware, and New Jersey and from ocean cruises off the U.S. East Coast were examined to determine spawning locations in the ocean, cross-shelf distributions of larvae, and movements of spot (Leiostomus xanthurus) into estuaries. Spot spawn du...

The recently discovered mass mortality of fishes from the Tanis Site in the North Dakota portion of the Late Cretaceous Hell Creek Formation contains many well-preserved, three-dimensional skeletons. Among these are representatives of two acipenseriform families, Acipenseridae (sturgeons) and Polyodontidae (paddlefishes). This paper describes two n...

Batrachoidiformes are benthic fishes that utilize the undersides of rocks as spawning nests. Their larvae are attached to the nest and nourished by a large yolk sac. The evolutionary shift from feeding, free-swimming larvae to sedentary larvae that are reliant on their yolk sac for nutrition can lead to changes in skeletal development. Batrachoidif...

Although the Cretaceous is widely regarded as a time of great evolutionary transition for the freshwater fish fauna of North America, the fossil record of this period is notoriously poor, consisting mostly of fragments and isolated skeletal elements. Exceptions include the acipenseriforms, discussed in this paper, and some exceedingly rare teleosts...

American Shad Alosa sapidissima is an anadromous clupeid that once supported a robust fishery but has declined drastically throughout its native range due to overfishing, dam proliferation, and poor water quality. A hatchery program on the James River in Virginia was introduced in 1992 to support the recovery of stocks. Following a moratorium of th...

Compilation of lower actinopterygians including morphology and taxonomy of Oalaleoniscimorphs, Stem neopterygians, and Chondrostei.

The fossil record of the family Acipenseridae (sturgeons) extends to the Late Cretaceous (c. 85 MY), with a ghost lineage extending to approximately 120 MY when the first members of the family Polyodontidae are known. Much of the fossil record of Acipenseridae is formed by isolated and fragmentary dermal bones, which bear characteristic surface orn...

Reliable estimation of phylogeny is central to avoid inaccuracy in downstream macroevolutionary inferences. However, limitations exist in the implementation of concatenated and summary coalescent approaches, and Bayesian and full coalescent inference methods may not yet be feasible for computation of phylogeny using complicated models and large dat...

Museum specimens serve as the bedrock of systematic and taxonomic research and provide the basis for repeatability or reinterpretation of preserved aspects of phenotypes. Specimens are also fundamental to fields such as ecology, behavior, and development. Each specimen is a record of biodiversity and documents a particular species present at a part...

Predation on the federally-endangered Atlantic Sturgeon (Acipenser oxyrinchus), and sturgeons generally is understudied. Most predation is presumed to occur on eggs and larvae, and be the result of interactions with other aquatic organisms, primarily other fishes. Predation on larger juvenile sturgeon by terrestrial and avian predators remains larg...

Extant members of Acipenseridae are generally classified in four genera: Scaphirhynchus, Pseudoscaphirhynchus, Huso and “Acipenser,” which is widely recognized to be paraphyletic. Advances have been made in understanding the systematic relationships among sturgeons based on both morphological and molecular data. Analysis of mitochondrial DNA data s...

The family †Peipiaosteidae contains the genera † Peipiaosteus , † Stichopterus , † Spherosteus , † Yanosteus , and † Liaosteus , all from Late Jurassic to Early Cretaceous deposits of China, Russia, Kazakhstan, and Mongolia. Although the family has taxonomically expanded since it was first established for † P. pani Liu and Zhou, 1965, the amount of...

American Shad, Alosa sapidissima, is an anadromous alosine clupeid that inhabits a native range spanning the coastal waters from Newfoundland to Florida. Concern about the significant decline in landings of American Shad in Virginia prompted management plans that ended in a complete moratorium of an historically significant fishery in 1994. The Vir...

The caudal-fin skeleton is a primary data source for systematics of fishes, with characters from this complex being proposed as synapomorphies at many taxonomic levels. Batrachoidiformes is recognized as monophyletic, although intraordinal relationships are unclear. Likewise, interrelationships of Batrachoidiformes to other percomorphs are not well...

The association between lateral‐line canals and skull bones in fishes has been the subject of several studies and raised a series of controversies, particularly with regard to the hypothesized role of lateral‐line organs (i.e. neuromasts) in osteogenesis and the consequences for hypotheses of homology of the bones associated with lateral‐line canal...

Dispersal sets the fundamental scales of ecological and evolutionary dynamics and has important implications for population persistence. Patterns of marine dispersal remain poorly understood, partly because dispersal may vary through time and often homogenizes allele frequencies. However, combining multiple types of natural tags can provide more pr...

The caudal-fin skeleton is a primary data source for systematics of fishes, with characters from this complex being proposed as synapomorphies at many taxonomic levels. Batrachoidiformes is recognized as monophyletic, although intraordinal relationships are unclear. Likewise, interrelationships of Batrachoidiformes to other percomorphs are not well...

Acta Zoologica has played a key role as a publishing outlet for advancing zoological knowledge since its foundation in 1920 by Nils Holmgren. With the journal celebrating its centennial, we have assembled a virtual issue that celebrates some of the morphological highlights from the history of Acta Zoologica, which has been a venue for precise and d...

Sexual dimorphism of the snout has evolved independently in at least four separate clades of the gymnotiform family Apteronotidae. This phenomenon may help identify sex, except in the absence of mature individuals, and has led to confused taxonomy for several species. We examined a large collection of Compsaraia samueli collected during the breedin...

The bony-tongue fishes, Osteoglossomorpha, have been the focus of a great deal of morphological, systematic, and evolutionary study, due in part to their basal position among extant teleostean fishes. This group includes the mooneyes (Hiodontidae), knifefishes (Notopteridae), the abu (Gymnarchidae), elephantfishes (Mormyridae), arawanas and piraruc...

The zoarcoid family Bathymasteridae contains seven species in three genera (Bathymaster, Rathbunella, Ronquilus) found in the North Pacific Ocean. Although several synapomorphies have been identified for the family, molecular analyses recover the family as a paraphyletic grade. The goals of this study are to provide a description of the skeleton of...

Citation for this article: Kovalchuk, O. M., and E. J. Hilton. 2017. Neogene and Pleistocene sturgeon (Acipenseriformes, Acipenseridae) remains from southeastern Europe. Journal of Vertebrate Paleontology, 37:5, e1362644, DOI: 10.1080/02724634.2017.1362644

The skeleton of the jaws and neurocranium of sturgeons (Acipenseridae) are connected only through the hyoid arch. This arrangement allows considerable protrusion and retraction of the jaws and is highly specialized among ray-finned fishes (Actinopterygii). To better understand the unique morphology and the evolution of the jaw apparatus in Acipense...

Although the form and function of feeding apparatus structures and diet composition are linked in adult fishes, it is often not clear when during ontogeny ecomorphological patterns develop, enabling early life history stage (ELHS) fishes to partition foraging niches and reduce competition. Species of drums (Sciaenidae) demonstrate tremendous variab...

Executive Summary Speckled trout (Cynoscion nebulosus) is the focus of an important recreational fishery in the southeastern United States. Speckled trout in Virginia has been cited as both a transitional population and as a mostly non-migratory population. The degree of residency is important to understand for the effective management of the speci...

The head is considered the major novelty of the vertebrates and directly linked to their evolutionary success. Its form and development as well as its function, for example in feeding, is of major interest for evolutionary biologists. In this study, we describe the skeletal development of the cranium and pectoral girdle in Siberian (Acipenser baeri...

The comparative morphology of the scales of roundscale spearfish Tetrapturus georgii and white marlin Kajikia albida was investigated. In addition, variation in scale morphology across different body regions within each species was analysed. Although considerable morphological variation was observed among scales from different body regions in both...

The Atlantic Sturgeon, Acipenser oxyrinchus oxyrinchus, is a large member of the family Acipenseridae, historically reaching lengths of at least 4.6 m in length (with some estimates of 5–6 m). In North America, A. o. oxyrinchus occurs in major rivers and coastal environments along the east coast from Labrador, Canada to Florida, USA; there are also...

Shortnose Sturgeon = SNS (Acipenser brevirostrum) is a small diadromous species with most populations living in large Atlantic coast rivers and estuaries of North America from New Brunswick, Canada, to GA, USA. There are no naturally land-locked populations, so all populations require access to fresh water and salt water to complete a natural life...

"Apteronotus" bonapartii (Castelnau 1855) was described based on a single specimen caught in a lake draining into the Río Ucayali, Perú, and is now reported from several rivers in South America. Because the generic placement of this species is currently uncertain, in this paper we use the genus name "Apteronotus" within quotes for reference to "Apt...

The growth and reproductive characteristics of Longnose Gar, Lepisosteus osseus, from the tidal portions of the major rivers in Virginia were analyzed using a three-dimensional population demographic model. This was the first study concerning Longnose Gar to test multiple growth models, and the biphasic double von Bertalanffy model best fit the dat...

Drums (family Sciaenidae) are common in tropical to temperate coastal and estuarine habitats worldwide and present a broad spectrum of morphological diversity. The anatomical variation in this family is particularly evident in their feeding apparatus, which may reflect the partitioning of adult foraging habitats. Adult and early life history stage...

This study provides a complete description of the osteology of the crescent gunnel Pholis laeta based on cleared-and-stained specimens and X-rays to help provide sufficient morphological data to generate a robust phylogeny for the family Pholidae. Pholis laeta exhibits high variation in the structure of its caudal skeleton. The length of the preura...

The caudal-fin skeleton is a primary data source for studies of the systematics of fishes, with characters from it being proposed as synapomorphies at many levels of organization. Batrachoidiformes is recognized as a monophyletic group, although the interrelationships among the genera and species are not entirely clear. Similarly, the relationships...

Three newly discovered larval specimens of the genus Muraenolepis collected from the waters of the western Antarctic Peninsula are described. Knowledge of their natural history is sparse and information about their early life history is based on only a few larval stages. Here, the available literature on larval eel cods is reviewed, and the specime...

Increases in human populations along coasts have altered the estuarine nursery habitats that are important for many aquatic organisms. These perturbations include changes to the sensory environment due to increased turbidity resulting from runoff and nutrient loading; these changes are occurring faster than fish species can become adapted to the ne...

Many of the primary groups of fishes currently recognized have been established through an iterative process of anatomical study and comparison of fishes that has spanned a time period approaching 500 years. In this paper we give a brief history of the systematic morphology of fishes, focusing on some of the individuals and their works from which w...

This is the first in a planned series of studies in which we examine the cranial muscle ontogeny of exemplar taxa of actinopterygian clades to obtain a better understanding of the evolution of the cranial musculoskeletal system within the Actinopterygii. The Longnose Gar, Lepisosteus osseus, is a member of the basal actinopterygian family Lepisoste...

The anatomy of the feeding apparatus in fishes, including both oral and pharyngeal jaw elements, is closely related to the ecology of a species. During ontogeny, the oral and pharyngeal jaws undergo dramatic changes. To better understand how such ontogenetic changes occur and relate to the feeding ecology of a species, ontogenetic series of four cl...

Comparing larval fish assemblages in different estuaries provides insights about the coastal distribution of larval populations, larval transport, and adult spawning locations (Ribeiro et al. 2015). We simultaneously compared the larval fish assemblages entering two Middle Atlantic Bight (MAB) estuaries (Delaware Bay and Chesapeake Bay, USA) throug...

The structure and ontogeny of lateral-line canals in the Rock Prickleback, Xiphister mucosus, were studied using cleared-and-stained specimens, and the distribution and morphology of neuromasts within lateral-line canals were examined using histology. X. mucosus has seven cephalic canals in a pattern that, aside from four branches of the infraorbit...

The Chinese sturgeon, Acipenser sinensis, is a large member of Acipenseridae now found only in the Yangtze River and the Yellow and East China seas. The goal of this paper was to describe the skull of A. sinensis in the context of recent anatomical and systematic studies of sturgeons. Five specimens (354–670 mm standard length) were prepared as ske...

Larvae of Atlantic croaker Micropogonias undulatus enter Mid-Atlantic Bight estuaries annually between September and February. A high prevalence of ectoparasitic crustacean infection of ingressing larval M. undulatus was observed in Chesapeake Bay; this ectoparasite was identified as a species of Lepeophtheirus within the copepod family Caligidae f...

Comparing larval fish assemblages in different estuaries provides insights about the coastal distribution of larval populations, larval transport, and adult spawning locations. We simultaneously compared the larval fish assemblages entering 2 Middle Atlantic Bight (MAB) estuaries (Delaware Bay and Chesapeake Bay, USA) through weekly sampling from 2...

Acipenseriformes hold an important place in the evolutionary history of bony fishes. Given their phylogenetic position as extant basal Actinopterygii, it is generally held that a thorough understanding of their morphology will greatly contribute to the knowledge of the evolutionary history and the origin of diversity for the major osteichthyan clad...

The two members of the genus Xiphister, Xiphister atropurpureus and Xiphister mucosus, are inter- and subtidal marine fishes from the west coast of North America, ranging from southern Alaska to southern California. Although both species were described over 150 years ago and portions of their anatomy have been described in several studies, a detail...

HE names of many historical figures in American ichthyology and herpetology ring loudly in the ears of those who study fishes, reptiles, and amphibians. These early American biological pioneers (i.e., active in the 100 years or so following the independence of the United States in 1776) were among the first to document and describe the ichthyologic...

The four species included in the family Cryptacanthodidae are eel-like, burrowing fishes distributed in the cold-temperate coastal waters of the North Pacific and the western North Atlantic. This study describes the osteology and aspects of the ontogenetic skeletal development of two species, Cryptacanthodes maculatus from the western North Atlanti...

Whole mitochondrial genome (mitogenome) sequences provide a powerful approach for investigating and hypothesizing relationships at a broad range of phylogenetic levels, and these data have been used extensively across the diversity of fishes. Mitogenome sequence studies have typically used an exemplar approach wherein one individual is sampled and...

Paralichthys lethostigma (Southern Flounder) inhabits the continental shelf and estuarine waters of the Gulf of Mexico and the east coast of the North Atlantic, from peninsular Florida to Albemarle Sound in North Carolina. Between 30 May and 20 August 2012, we collected 15 juvenile (71-192 mm) Southern Flounder in fyke nets in the Mattaponi River,...

The link between the structure of the feeding apparatus, sensory modality (a sense or combination of senses relied on by an organism) and diet in early life history stage fishes is important for understanding ontogenetic shifts in foraging habitats during ontogeny. Species of the family Sciaenidae are used to examine how ontogenetic changes in feed...

Early life history stage (ELHS) fishes are more susceptible to starvation than adults and successful feeding at these stages is critical. Members of the family Sciaenidae are an excellent model group to investigate ontogenetic diet shifts because as adults they occupy a broad spectrum of feeding niches. Stomachs have been excised from 376 specimens...

The lower jaw of Lepisosteus osseus has been described as containing a U-shaped cartilaginous structure identified as a detached portion of Meckel’s cartilage. We investigated this structure through study of a growth series of L. osseus, including cleared-and-stained specimens and histological preparations. Meckel’s cartilage is well developed by 1...

Chesapeake Bay is the largest estuary in the USA and comprises vast areas of polyhaline to freshwater, tidal fish habitat. The Bay experiences large temperature differences between winter and summer, which in combination with the variety of salinities enables approximately 240 species of fish to be temporary inhabitants. This dynamic environment le...

The prowfish, Zaprora silenus, is the sole member of the family Zaproridae. It is a large, relatively elongate species with a robust head and body, and it feeds primarily on jellyfishes. Although the larvae and juveniles are pelagic, the adults are demersal, and the species is widely distributed from Southern California around the Pacific Rim to Ho...

The seasonal movements of Lepisosteus osseus (Longnose Gar) are largely unknown. The goal of this project was to characterize spawning movements and seasonal distributions by using acoustic tagging methods and examining historical catch records from a trawl survey. This is the first time that movements have been studied for an estuarine population...

Directed commercial fisheries for American shad Alosa sapidissima in the primary Virginia tributaries of the Chesapeake Bay have been under moratorium since 1994. Monitoring of adult American shad within these rivers has been ongoing since 1998 through a cooperative program involving commercial fishers. The monitoring program is designed to mimic t...

The present study of Lepisosteus osseus dimorphism expands upon previous work by examining a broader array of morphometric characters while removing the bias associated with overall body length. A stepwise discriminant function analyses (swDFA) found that five characters best distinguish the sexes: head width, mid-snout width, anal-fin height, anal...

The taxonomic diversity of bony fishes presents a seemingly endless diversity of forms that reflect the varied life history, ecology, and behavior of these animals. Matched to this taxonomic diversity, the skeletons of bony fishes also display a complex and diverse array of forms. The skeleton provides the architectural support for the musculature...

As eloquently stated by Nelson and Ladiges (2001) in the passage above, the way that systematic data is analyzed almost certainly will affect how it becomes interpreted. Often the way in which data are analyzed will depend on the type of data being considered. Regardless of the methods employed or data under consideration, there are several levels...

Sturgeons of the family Acipenseridae comprise 25 extant species, making it the most species-rich extant family of basal (i.e., nonteleostean) actinopterygians. Because of their basal position within Actinopterygii, the anatomical study of sturgeons has a long and rich history, although there remains much to be discovered. Here we describe and illu...

Fisheries for American shad in the Virginia waters of Chesapeake Bay have been under moratorium since 1994. An offshore mixed-stock fishery operated beyond 1994, but chronic low abundances of American shad within many Atlantic coastal states prompted closure of that fishery in 2005. Although juvenile abundances have been monitored in Virginia s...

The monotypic Indo-Pacific genus Parastromateus Bleeker, 1864 is morphologically peculiar among carangid fishes in its overall body form and has been difficult to place phylogenetically. This has been partly the result of a lack of detailed morphological data for this and other carangid fishes. Here, we describe and analyze the osteology of Parastr...

Phenoscape Guide to Character Annotation. We describe our standard practices for annotation of entities and qualities in the Guide to Character Annotation. Our online version describes more specialized cases and issues (https://www.phenoscape.org/wiki/Guide_to_Character_Annotation). (0.09 MB DOC)

Background: The wealth of phenotypic descriptions documented in the published articles, monographs, and dissertations of phylogenetic systematics is traditionally reported in a free-text format, and it is therefore largely inaccessible for linkage to biological databases for genetics, development, and phenotypes, and difficult to manage for large-...

We present a redescription of †Chondrosteus acipenseroides, a basal member of the order Acipenseriformes (sturgeons, paddlefishes and their fossil relatives) from the Lower Jurassic of England. †Chondrosteus is known from several whole or partial skeletons and many isolated fragmentary elements. Even on many of the articulated skeleton and skull sp...

The Graveldiver, Scytalina cerdale, is a small, poorly known burrowing fish from the intertidal and subtidal zones of the west coast of North America, ranging from south-central California to Alaska. This is the sole member of the family Scytalinidae, which is included in the Zoarcoidei. Although it was described over 120 years ago, it is rare in n...

In 2006, we (Grande & Hilton, 2006) described a well-preserved fossil sturgeon (Acipenseridae) from the Late Cretaceous of Montana and proposed the name † Psammorhynchus longipinnis Grande & Hilton for the new species. Through accidental discovery of an on-line taxonomic database of flatworms (Tyler et al., 2006) and subsequent investigation, we re...

The skeletal anatomy of fossil hiodontids from western North America is examined based on newly-prepared specimens, including several specimens that were prepared using the acid transfer method and some using the 'lost fossil' technique. This study resulted in many new interpretations and clarifications, such as the presence of a curved tubular nas...

One focus of developmental biology is to understand how genes regulate development, and therefore examining the phenotypic effects of gene mutation is a major emphasis in studies of zebrafish and other model organisms. Genetic change underlies alterations in evolutionary characters, or phenotype, and morphological phylogenies inferred by comparison...

In this paper, we redescribe the apteronotid fish Orthosternarchus tamandua, the only species of its genus. Historically, O. tamandua was rare in collections and only limited anatomical data was available for this species. However, numerous specimens have become available recently as a result of deep-water trawls in the main channel of the Amazon R...

Ontogeny often provides the most compelling evidence for primary homology in evolutionary developmental studies and is critical to interpreting complex structures in a phylogenetic context. As an example of this, we document the ontogenetic development of the caudal skeleton of Caranx crysos by examining a series of cleared and stained larval and p...

The structure and composition of the ventral portion of the occipital region of the skull in Arapaima gigas (Osteoglossidae) is unique among teleostean fishes, and past comparative anatomical studies have variously interpreted it as containing only the basioccipital or the basioccipital fused to one or two vertebral centra. By studying an ontogenet...

Here we document sexual dimorphism in both external measurements of the head and discrete features of the skull in Apteronotus bonapartii. To quantify morphological variation in A. bonapartii, ten external morphometric measurements were taken from the head and body of 58 individuals. By using Discriminant Function Analysis, we found that the best p...

The pre-Pleistocene fossil record of sturgeons (family Acipenseridae) from North America is reviewed based on a survey of reports in the literature and firsthand examination of specimens in museum collections. We provide a redescription of the only known specimen of † Protoscaphirhynchus squamosus(Late Cretaceous, Montana), a very poorly preserved...

The Quillfish, Ptilichthys goodei, is a slender, elongate fish distributed along the coastline of the North Pacific from Oregon to the Sea of Japan. It is the sole mem- ber of the monotypic family Ptilichthyidae, which is classified among the Zoarcoidei (eelpouts and their allies). Little is known of its osteology and there is much con- flicting in...