Lance Grande

A Comprehensive Phylogenetic Study of Amiid Fishes (Amiidae) Based on Comparative Skeletal Anatomy. an Empirical Search for Interconnected Patterns of Natural History

ABSTRACT The comparative osteology, phylogenetic relationships, and historical biogeography of all known taxa of fossil and living amiid fishes (Halecomorphi: Amiidae) are investigated in detail. Previously, the detailed osteology of nearly all fossil amiids was unknown. We present the first well-supported comprehensive phylogeny for fossil and living amiid fishes. We synthesize clearly documented phylogenetic data on amiids and other halecomorph fishes with other historical phenomena such as ontogeny, historical biogeography, stratigraphic paleontology, and paleoecology (both “stationary” and “historical”). We also use our study of halecomorph fishes as a platform to explore several fundamental methodological and theoretical concepts important to phylogenetic/evolutionary investigations. These concepts pertain mainly to (1) the use of comparative empirical data to interpret various historical patterns and (2) the practice of integrating fossil and living species together in original (i.e., non-literature...

An overview of Acipenseriformes

Acipenseriformes occupy a special place in the history of ideas concerning fish evolution, but in many respects, phylogenetic studies of the group remain in their infancy. Even such basic questions as the monophyly of Acipenser (the largest genus) are unanswered. We define relationships based on comparative osteology, which allows us to incorporate well-preserved fossils into analyses. Acipenseriformes has existed at least since the Lower Jurassic (approximately 200 MYBP), and all fossil and recent taxa are from the Holarctic. Phylogenetic relationships among Paleozoic and Early Mesozoic actinopterygians are problematic, but most workers agree that Acipenseriformes is monophyletic and derived from some component of ‘paleonisciform’ fishes. (‘Paleonisciformes’ is a grade of primitive non-neopterygian actinopterygians, sensu Gardiner 1993.) Taxa discussed in comparison here are: †Cheirolepis, Polypterus, †Mimia, †Moythomasia, †Birgeria, †Saurichthys, Lepisosteus and Amia. We review generic diversity within the four nominal families of fossil and recent Acipenseriformes (†Chondrosteidae, †Peipiaosteidae, Polyodontidae, and Acipenseridae), and provide a cladogram summarizing osteological characters for those four groups. Monophyly of the two extant families is well-supported, but there are no comprehensive studies of all of the known species and specimens of †Chondrosteidae and †Peipiaosteidae. As a result, sister-group relationships among †Chondrosteidae, †Peipiaosteidae, and Acipenseroidei (= Polyodontidae + Acipenseridae) are unresolved. We discuss five features fundamental to the biology of acipenseriforms that benefit from the availability of our new phylogenetic hypothesis: (1) specializations of jaws and operculum relevant to jaw protrusion, feeding, and ram ventilation; (2) anadromy or potamodromy and demersal spawning; (3) paedomorphosis and evolution of the group; (4) the bioegeography of Asian and North American polyodontids and scaphirhynchines; and (5) the great abundance of electroreceptive organs in the rostral and opercular regions. Finally, we summarize our nomenclatural recommendations.

Osteology and Phylogenetic Relationships of Fossil and Recent Paddlefishes (Polyodontidae) with Comments on the Interrelationships of Acipenseriformes

ABSTRACT The comparative osteology and phylogenetic relationships of fossil and living paddlefishes (Polyodontidae) are investigated in detail for the first time. This peculiar, poorly known group is of great significance to phylogenetic studies of primitive actinopterygians, because it is one of only two chondrostean families that have survived to the present. Consequently the group is frequently used as an outgroup for studies of the many fossil chondrostean groups and for higher-level studies of actinopterygian (and even osteichthyan) interrelationships. The family has a long but spotty fossil record dating back to the Upper Cretaceous, including species represented by relatively complete skeletons or at least skulls. These relatively complete fossils are extremely rare and belong to the species †Paleopsephurus wilsoni MacAlpin, 1947 from the Upper Cretaceous Hell Creek Formation of Montana (redescribed here); †Polyodon sp. nov. from the lower Paleocene Tullock Formation of Montana (described here); an...

Taxonomic Impediment or Impediment to Taxonomy? A Commentary on Systematics and the Cybertaxonomic-Automation Paradigm

Marcelo R. de Carvalho AE Flavio A. Bockmann AE Dalton S. Amorim AE Carlos Roberto F. Brandao AE Mario de Vivo AE Jose L. de Figueiredo AE Heraldo A. Britski AE Mario C. C. de Pinna AE Naercio A. Menezes AE Fernando P. L. Marques AE Nelson Papavero AE Eliana M. Cancello AE Jorge V. Crisci AE John D. McEachran AE Robert C. Schelly AE John G. Lundberg AE Anthony C. Gill AE Ralf Britz AE Quentin D. Wheeler AE Melanie L. J. Stiassny AE Lynne R. Parenti AE Larry M. Page AE Ward C. Wheeler AE Julian Faivovich AE Richard P. Vari AE Lance Grande AE Chris J. Humphries AE Rob DeSalle AE Malte C. Ebach AE Gareth J. Nelson

Redescription of Hypsidoris farsonensis (Teleostei: Siluriformes), with a reassessment of its phylogenetic relationships

ABSTRACT †Hypsidoris farsonensis Lundberg and Case (1970) from the Eocene Green River Formation of Wyoming, is redescribed in detail based on much new material. The new material consists of (1) better preparations of the original type and referred specimens, and (2) many previously unreported specimens with exceptionally detailed preservation. Based on new information presented here †H. farsonensis is interpreted (A) not to belong in Ictaluridae as originally proposed, and (B) to be the sister group to all known catfish families other than Diplomystidae. Diplomystidae appears to be the sister group to †Hypsidoris plus all other known catfishes. Because of its apparent phylogenetic position (sister group to a group containing thirty nominal families), †Hypsidoris is given superfamilial (†Hypsidoroidea, new superfamily) and familial (†Hypsidoridae, new family) rank, and may be more relevant to our understanding of the early evolution of siluriform subgroups than previously thought. Catfishes (Siluriformes) ...

FRESHWATER STINGRAYS OF THE GREEN RIVER FORMATION OF WYOMING (EARLY EOCENE), WITH THE DESCRIPTION OF A NEW GENUS AND SPECIES AND AN ANALYSIS OF ITS PHYLOGENETIC RELATIONSHIPS (CHONDRICHTHYES: MYLIOBATIFORMES)

Abstract Freshwater stingrays from the Fossil Butte Member of the late early Eocene Green River Formation of Wyoming are reviewed, and a new genus and species of fossil stingray is described. †Asterotrygon maloneyi, n.gen., n.sp. is remarkably well preserved and is known from articulated skeletons of juveniles and adults, both males and females. It is distinguished from all Recent and fossil stingrays, including †Heliobatis radians from the same formation, by the unique presence of a dorsal fin covered with dermal denticles directly anterior to the caudal stings. Other characters that in combination distinguish the new fossil genus from all other stingrays include: retention of separate, individual vertebrae extending to the tail extremity instead of a cartilaginous rod posterior to caudal stings; dorsal surface of disc and tail covered by numerous, closely packed, minute denticles; tail relatively stout at base; and relative proportions of disc and tail. †Asterotrygon, n.gen. shares with certain stingray genera postorbital processes of neurocranium separated from a supraorbital process by a small notch in the supraorbital shelf, presence of both dorsal and ventral tail-folds posterior to caudal stings (and internally supported by rudimentary radial elements), and hyomandibulae separated from lower jaws by a gap that originally contained the hyomandibular-Meckelian ligament. A calcified angular cartilage between the hyomandibula and Meckels cartilage is tentatively identified in †Asterotrygon, n.gen. as well. †Asterotrygon, n.gen. is unquestionably a stingray, presenting many myliobatiform synapomorphies including caudal stings on the dorsal aspect of tail, lack of jugal arches in neurocranium, a thoracolumbar synarcual cartilage posterior to scapulocoracoid, absence of thoracic ribs, and laterally expanded, shelflike postorbital processes. †Asterotrygon, n.gen. and †Heliobatis primitively retain a narrow and slightly arched puboischiadic girdle and primitively lack calcified rostral elements in adults. A phylogenetic analysis of 23 stingray genera, two outgroups, and 44 informative morphological characters resulted in 35 equally most parsimonious trees. The strict consensus reveals the following hierarchical structure: Hexatrygon + (†Asterotrygon, n.gen., Plesiobatis, Urolophidae + (Urotrygonidae + (†Heliobatis + (Potamotrygonidae + (amphi-American Himantura, Pteroplatytrygon, Himantura, Taeniura, Dasyatis + (Gymnuridae + Myliobatidae)))))). Our resulting tree has nodes in common with previous phylogenetic analyses of stingrays (e.g., Hexatrygon is the most basal stingray genus; gymnurids and myliobatids [pelagic stingrays] are well-supported sister-groups), but includes novel components, such as a clade that includes all dasyatid genera (as a polytomy) and the component Gymnuridae + Myliobatidae. “Dasyatidae” is not monophyletic in any of the minimum-length trees obtained; Urolophidae (Urolophus and Trygonoptera) and Urotrygonidae (Urobatis and Urotrygon) are both monophyletic, but are not sister-groups. †Asterotrygon, n.gen. forms a clade with urolophids in 21 of the 35 equally most parsimonious trees. Successive approximations weighting adds only one additional node in relation to the strict consensus, which unites Pteroplatytrygon, Dasyatis, and Himantura sensu stricto (in a polytomy) with Gymnuridae + Myliobatidae. The resulting stingray phylogeny is at odds with previous phylogenies mostly regarding the affinities of amphi-American Himantura and Taeniura, which do not form a monophyletic group with the South American freshwater stingrays (Potamotrygonidae) in any of the minimum-length trees obtained. Similar to most elasmobranch groups, stingrays display much character conflict, and cladogram topologies are very sensitive to changes in character coding. Due to a high degree of character variation present in certain generic-level terminal taxa, a more fully representative species-level phylogeny is necessary to clarify the systematic importance of tail-fold configuration, ceratobranchial fusion patterns, and other characters discussed in our study. Three additional synapomorphies of stingrays were uncovered by our study, pertaining to the configuration of the basihyal, first pair of hypobranchial cartilages, and to the forward extension of the basibranchial copula. Our phylogenetic results imply the following biogeographic patterns: the relationships of †Asterotrygon, n.gen. demonstrate a strong Indo-west Pacific historical correlation, while †Heliobatis displays an affinity with the Americas; the node containing the greatest diversity of modern stingrays (“Dasyatidae” + (Gymnuridae + Myliobatidae)) evolved only after an American stingray lineage was established sometime earlier than the early Eocene; and potamotrygonids date at least from the late early Eocene, and not the Miocene, as previous studies have implied. The mechanism responsible for the invasion of the potamotrygonid ancestor into South America could indeed have been a marine transgression as advocated by other authors, albeit a much earlier (pre-Miocene) one, during either the Late Cretaceous or the late Paleocene to early Eocene.

Early development of the actinopterygian head. I. External development and staging of the paddlefish Polyodon spathula

A large sample of embryological material of the North American paddlefish Polyodon spathula (Acipenseriformes: Polyodontidae) confirms that early development in Polyodon is very similar to that reported for the sister group of Polyodontidae, the sturgeons (Acipenseridae). Polyodon illustrates many basic aspects of acipenseriform (and actinopterygian) head development that have not been adequately described. In this paper, we provide an overview of external features of cranial development using scanning electron microscopy. The observations are correlated with staging schemes previously proposed for paddlefishes and other acipenseriforms. Events that occur after the start of neurulation (stage 19) to the start of feeding (stage 46) are emphasized. New information on the structure and folding of the mandibular and hyoid segments permits an understanding of the early development of the pharyngeal region. In addition, we offer new descriptions of the hatching gland, the olfactory organ, the sensory barbel, and the initiation of paddle outgrowth. We also comment on the mode of origin of the hypophysis, and refute the notion that it is derived from the lips of the anterior neuropore as suggested in older literature. This information sets the stage for future comparative and experimental studies of the embryology of basal actinopterygians.

Skeletal Anatomy of the Shortnose Sturgeon, Acipenser brevirostrum Lesueur, 1818, and the Systematics of Sturgeons (Acipenseriformes, Acipenseridae)

Abstract 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 illustrate the skeletal anatomy of the shortnose sturgeon, Acipenser brevirostrum, as a representative of the family Acipenseridae. Acipenser brevirostrum, which is distributed along the east coast of North America, is a relatively small species of sturgeon, reaching a maximum of just over 1 m in total length. Our study is based on 105 skeletal and 147 alcohol-stored specimens representing a broad range of ontogenetic stages (ca. 18 to 1000+ mm TL). This study emphasizes the bony portions of the skeleton, their ontogeny, and parts of the skeleton that persist as cartilaginous elements into the adult stage; the earliest stages of development of the chondrocranium, however, will be the subject of a future project. In the present study, we intend to provide baseline data for future comprehensive ontogenetic and morphological studies of Acipenseridae. Although the Acipenseriformes are extremely morphologically derived compared to most basal actinopterygians, these data will be useful in broader systematics studies of basal Actinopterygii generally. Based on previous studies of acipenseriform phylogeny and using new anatomical data collected in this study, we studied the phylogenetic relationships of fossil and living acipenserids. The monophyly of Acipenseriformes is supported by two synapomorphies: palatoquadrates with symphysis between pars autopalatina and the absence of premaxillae and maxillae. Contrary to other recent studies, we recover †Chondrosteus as most basal among Acipenseriformes rather than †Peipiaosteus. †Peipiaosteus + Acipenseroidei is supported by the presence of fewer than seven but more than one branchiostegals, the posterior margin of the branchiostegals serrated, the absence of ossified basibranchials, and the absence of teeth on the gill rakers. Acipenseroidei ( =  Polyodontidae + Acipenseridae) is supported by one synapomorphy (presence of ventral rostral bones). Monophyly of both Polyodontidae and Acipenseridae is well supported. The family Polyodontidae (represented in our analysis by †Protopsephurus and Polyodon) is supported by the presence of well-developed anterior and posterior divisions of the fenestra longitudinalis, the parietals extending posterior to posttemporals, the presence of stellate bones, the ascending process of parasphenoid extending perpendicularly from the lateral margin of the parasphenoid, a serrated posterior margin on the subopercle, and the presence of “microctenoid” scales. The family Acipenseridae is supported by 11 synapomorphies: arching of the rostral canal, a single posteriormost ventral rostral bone, branchiostegals of different shapes, dorsalmost branchiostegal pillar-like and laterally concave, the presence of the palatal complex, an anterior shelf of hypobranchial one, a continuous series of median dorsal scutes extending from skull to dorsal fin, the supracleithrum reaching the level of extrascapulars, a cardiac shield formed by shoulder girdle, the clavicle–cleithrum suture tight and interdigitating, and the presence of a supracleithral cartilage. Within Acipenseridae, we recovered three groupings; Acipenser is not monophyletic. Within Acipenseridae, two supraspecific taxonomic groups are recognized and defined: Husinae (new usage) includes A. ruthenus and Huso huso, and Pseudoscaphirynchinae new subfamily includes A. stellatus and Pseudoscaphirhynchus. Husinae is defined by the frontal bones meeting in midline and a slight medial dermopalatine expansion, although neither of these characters is unique to this clade. Acipenser baerii is more closely related to Husinae than other acipenserids based on the presence of a variable number of distinctly raised prominences on the ventral rostral bones but is excluded from the subfamily pending further study, including denser taxon sampling within Acipenser. The new subfamily Pseudoscaphirynchinae is defined by having the horizontal arm of jugal bone undercut the nasal capsule, a uniquely derived character. Although suitable specimens of all species of Acipenseridae were not available, we note that this is the first robust morphological phylogenetic study addressing species-level relationships for this family, and we hope our study will serve as a baseline study for future comparative anatomical and systematic studies of Acipenseridae.

Revision and redescription of the genus Astephus (Siluriformes: Ictaluridae) with a discussion of its phylogenetic relationships

ABSTRACT †Astephus antiquus from Eocene Green Formation of Wyoming and Utah is redescribed in detail based on newly obtained material, and the position of †Astephus among Siluriformes is reconsidered. Phylogenetic evaluation of the genus is based on descriptive information from †Astephus antiquus, the only species known by nearly complete specimens and a species that contains the type species for the genus. It was determined that Lundbergs (1970, 1975a) assessment of †Astephus as an ictalurid is the most probable interpretation of available information. Assuming that †Astephus is an ictalurid, there is strong evidence indicating that it is the sister group to a group containing all other members of the family. †Astephus calvus (Cope), the type for the genus (designated by Jordan, 1919), is considered here to be a subjective junior synonym of †Astephus antiquus (Leidy). The only other valid species recognized here as probably belonging in the genus (and probably distinct from †A. antiquus) is †A. resimus ...

A GREEN RIVER (EOCENE) POLYCHROTID (SQUAMATA: REPTILIA) AND A RE-EXAMINATION OF IGUANIAN SYSTEMATICS

Abstract A pleurodontan iguanian from the Green River Formation (Eocene) is described in detail and named. The new taxon is known only from a single specimen preserving all areas of the body. Although many of the bone surfaces are eroded, almost all of the skeleton is present and some cartilaginous elements are preserved. The new taxon shares important characteristics with the extant anisolepines and leiosaurines, including the morphology and placement of the caudal autotomy planes, the postxiphisternal inscriptional ribs, and notched or fenestrated clavicles that are expanded proximally. This is the earliest complete iguanian known from the Americas and the earliest known iguanian that may be confidently referred to an extant “family.” A phylogenetic analysis including this taxon and other fossil and extant iguanians offers some support for the monophyly of Polychrotidae sensu lato, Tropiduridae sensu lato, and non-acrodont iguanians (Pleurodonta).