Mesozoic Fishes 5 – Global Diversity and Evolution

Katia A. GONZÁLEZ-RODRÍGUEZ, Luis ESPINOSA-ARRUBARRENA and Gerardo GONZÁLEZ-BARBA: An overview of the Mexican fossil fish record
[S. 9–34, 8 Abbildungen (5 farbig), 1 Anhang]

The fossil fish record of Mexico is poorly known despite numerous recent discoveries of new localities that represent different ages and environments. The stimulus for a new era in Mexican paleoichthyology occurred in 1976, with the arrival of Shelton P. APPLEGATE in the country. Before “Shelly’s” time, the study of fossil fishes was delegated to geologists and paleontologists mostly interested in geological exploration for oil and other resources, not vertebrate paleontology. The diverse geological episodes that occurred in Mexico during millions of years generated a large array of different environments that supported a great diversity of biotas, including fishes. Paleozoic ichthyological records in Mexico are scarce, represented only by three reports of the shark Helicoprion. Early Mesozoic fishes have not yet been discovered, but Late Jurassic deposits contain halecomorphs, pycnodontiforms and ichthyodectiforms. So far, the most abundant records correspond to Cretaceous marine fishes. Some localities such as Tlayúa (Puebla), Vallecillo (Nuevo León), El Chango (Chiapas), and El Rosario (Coahuila) are Konservat-Lagerstätten. Some others were discovered more recently and, although their entire diversity is still unknown, certain families such as Macrosemiidae and Ichthyotringidae have already been reported for the first time in the New World. Mexican Cenozoic records, discovered mainly in the Baja California Peninsula, include abundant marine shark and ray teeth but only a few teleost remains. Freshwater teleost records are almost entirely confined to central Mexico and, according to the known records, they seem to be biased towards the Neogene (following the final episodes of the Sierra Madre Occidental and the formation of the Mexican Volcanic Belt). Study of Mexican fossil fishes will help us to understand the patterns of distribution and the phylogenetic relationships of the groups present in this part of the world, and the collaboration of international paleoichthyologists will increase our knowledge of the fossil fishes of Mexico.

Kathryn E. MICKLE: Revisiting the actinopterygian preoperculum
[S. 35–71, 25 Abbildungen, 1 Tabelle]

The preoperculum has been a closely studied character among actinopterygians. Previous studies have identified the preopercular conditions of palaeoniscoids as primitive, subholosteans as intermediate, and holosteans as advanced. Changes in the preoperculum across actinopterygians are thought to have functional implications regarding the jaw suspensorium and feeding mechanisms. Here, a wider study of the preoperculum in Paleozoic, Mesozoic, and Recent fishes reveals that the conventional wisdom that there is a gradual and progressive change from the palaeoniscoid condition to a more advanced condition in holostean and teleost fishes is an oversimplification. For instance, there are numerous palaeoniscoid fishes with vertical preopercula and specialized feeding regimes. When the preopercular conditions of Paleozoic and Mesozoic fishes are examined within a phylogenetic context, the original hypothesis is also not supported. A hindrance to this study is the fact that phylogenetic hypotheses for a wide variety of fishes are lacking. This character study highlights the need for strong phylogenetic hypotheses of relationships for a broad sampling of Paleozoic and Mesozoic actinopterygians, as well as the need for more in depth studies into specific morphological characters and interpretations regarding their homology.

Hugo MARTÍN-ABAD and Francisco José POYATO-ARIZA: Amiiforms from the Iberian Peninsula: historic review and research prospects
[S. 73–86, 6 Abbildungen, 1 Tabelle]

The fossil record of amiiform fishes from the Iberian Peninsula is known from 12 different sites. It extends along the three periods of the Mesozoic era, being much more abundant during the Early Cretaceous. The majority of these sites has yielded isolated remains, mostly teeth; complete and articulated specimens are known from three Konservat-Lagerstätten only: Montral-Alcover, El Montsec, and Las Hoyas. Generic and specific level assessments are possible in these three localities only.

The historical taxonomical problems of the cited amiiform taxa are commented. Special mention deserves the case of the genus Urocles (= Megalurus), traditionally cited from El Montsec and Las Hoyas. This genus is invalid since 1998, but its taxonomic history goes back to the 1830’s.

The amiiform fishes from Las Hoyas have traditionally been assigned to the same taxa as those coming from El Montsec, but they have not been studied in detail yet, so their taxonomical assessment is in need of confirmation. These specimens, characterized by a great quality of preservation and an abundant record, may provide significant information concerning the ontogenetic development of the fishes of this order.

Gloria ARRATIA and Hans-Peter SCHULTZE: Outstanding features of a new Late Jurassic pachycormiform fish from the Kimmeridgian of Brunn, Germany and comments on current understanding of pachycormiforms
[S. 87–120, 17 Abbildungen (9 farbig), 1 Tabelle]

A new pachycormiform, †Orthocormus roeperi n. sp., is described from the upper Kimmeridgian of Brunn, Bavaria, Germany. The well-preserved specimen provides new information on features of the head, vertebral column and fins. The rostrodermethmoid bears a pair of straight, large paramedial teeth; the premaxilla is sutured with the rostrodermethmoid; there are small conical teeth on the upper jaw, a large tooth on the posterior part of the premaxilla, and both large and small teeth on the maxilla; the lower jaw carries large teeth anteriorly and smaller ones posteriorly; a dermosphenotic with a short anterior process forms only a portion of the complete dorsal margin of the orbit. The vertebral column is formed by a persistent notochord without chordacentra, but with well-developed, protruding arcocentra in the caudal region. The scythe-like pectoral fins possess rays with long bases, scarcely segmented, and finely branched distally; the characteristic Y-like branching pattern described for other pachycormiforms is apparently missing. The dorsal and anal fins present characteristic lateral expansions at their bases, possibly to facilitate water flow. The unpaired fins have numerous long and slender basal fulcra preceding the principal rays. There are more than 100 caudal rays, including 32 epaxial and 24 hypaxial principal rays. Large lateral processes are present on the lateral wall of the well-developed arch of the parhypural and on the hypural plate, suggesting the presence of a powerful hypochordal longitudinalis muscle. A protruding structure, named here the scaly caudal apparatus, covers laterally part of the hypural plate and the bases of the principal rays. This peculiar structure has not been previously reported in any pachycormiform. The scaly caudal apparatus, formed by large modified scales with a precise arrangement, is interpreted as an adaptation to fast swimming comparable to that of modern tunas and may occur in other pachycormiforms such as †Sauropsis as well.

The results of a survey of other pachycormiforms as well as of the literature suggest that incomplete knowledge of pachycormiform morphology can be explained by incomplete and poor preservation of many specimens. There has been a tendency to generalize the presence of structures based on few taxa. The fish described here is the best-preserved pachycormiform from Bavaria, Germany, as well as from the Upper Jurassic worldwide. It presents previously unknown characters and also characters that contradict some previous assumptions. Incomplete knowledge of most characters confounds the placement of Pachycormiformes within Neopterygii.

Jeff LISTON: The plasticity of gill raker characteristics in suspension feeders: Implications for Pachycormiformes
[S. 121–143, 9 Abbildungen]

Pachycormids apparently represent part of the first radiation of the total group of teleosts, and therefore are important in understanding stem teleost phylogeny. Gill rakers (or fanunculi) are elements of the gill skeleton (branchial basket) in fishes that function primarily to protect respiratory lamellae, and sometimes have a secondary role in feeding. Characteristics of gill rakers have been used for taxonomic diagnosis and cladistic analysis of the interrelationships of Pachycormiformes, with particular importance for Leedsichthys and Asthenocormus. The material on which these determinations have been based is reviewed, along with the validity of the use of gill rakers in analyses of extinct fishes in general, based on their utility in extant fishes, following the presentation of a standardized nomenclature for these structures. Gill rakers are demonstrated to be an unreliable source of taxonomic characters in suspension feeders. The assignment of specimen PETMG F34 to Leedsichthys, solely based on the presence of elaborated but dissimilar gill rakers, is rejected, as there are no osteological resemblances to any other specimen of that taxon. The characters used to erect Leedsichthys notocetes are demonstrated to be artifacts generated by erosion and fracture, and this material is consequently synonymised within Leedsichthys problematicus.

Jeff LISTON, Michael G. NEWBREY, Thomas James CHALLANDS and Colin E. ADAMS: Growth, age and size of the Jurassic pachycormid Leedsichthys problematicus (Osteichthyes: Actinopterygii)
[S. 145–175, 13 Abbildungen, 3 Tabellen]

The Jurassic pachycormid osteichthyan Leedsichthys problematicus is renowned for having been able to achieve prodigious size for a bony fish. Building on work of MARTILL (1986a), a thorough examination of all known material was conducted in order to constrain estimates of the size of this animal and examine its rate of growth. Important specimens of Leedsichthys are described for the first time. The histology of Leedsichthys is reviewed, and the presence of growth annuli is used to establish ages for five specimens. Age and growth data were obtained from gill rakers (n=4) and lepidotrichia (n=2). Lepidotrichia show upward curvilinear growth profiles and ages ranging from 21 to 40 annuli, which are assumed to represent years. Both growth profiles start at a small size (0.26 and 0.33 mm radial distance), which is assumed to represent age 1. However, annuli can be lost near the margins of the elements. Gill rakers exhibit a sigmoidal growth profile. Age of gill rakers was estimated by adjusting the alignment of the inflection points of the growth profiles thereby giving adjusted ages. Gill rakers ranged in age from 19–38 annuli, but all show evidence of reabsorption of annuli near the focal points and at the margins of most elements. Sizes for the five individuals range from 8.0–16.5 m for ages of 19–40 years. Growth rate (0.01–0.05 K) was relatively slow as expected for a large, long-lived fish. At age 1, individuals were 1.6 m in length. Estimates for the length of L. problematicuscompare well with published lengths of other large suspension feeders such as those for basking and whale sharks.

Soledad GOUIRIC-CAVALLI and Alberto Luis CIONE: “Pholidophorus argentinus” DOLGOPOL DE SAEZ, 1939 from Upper Jurassic beds of the Neuquén Province of Argentina is not a pholidophoriform but an aspidorhynchid (Actinopterygii, Aspidorhynchiformes)
[S. 177–186, 4 Abbildungen (3 farbig)]

The Late Jurassic marine deposits of Argentina host a diverse fish fauna that is currently under study. One of the species is Pholidophorus argentinus DOLGOPOL DE SAEZ, 1939, which is based on the caudal region of a single specimen collected in the Neuquén Basin. Here we propose that the material comes from the Picún Leufú Formation of the Neuquén Basin. DOLGOPOL DE SAEZ assigned the fish to Pholidophorus AGASSIZ on the basis of a combination of characters that were preliminarily revised by one of us (AC) several years ago. It was concluded that the type specimen did not present any diagnostic character to justify erection of a different species or to allow an assignment to the genus Pholidophorus s. str. Consequently, the specimen was referred to as Halecomorphi indet. A detailed anatomical study of the holotype permits us now to assign it to the Family Aspidorhynchidae. It is remarkable that the caudal anatomy, especially the fin rays, of this family is scarcely known. In fact, this is the first description of the caudal fin of a Jurassic aspidorhynchid from the Southern Hemisphere.

Hans-Peter SCHULTZE and Gloria ARRATIA: The caudal skeleton of basal teleosts, its conventions, and some of its major evolutionary novelties in a temporal dimension
[S. 187–246, 24 Abbildungen (16 farbig), 4 Tabellen, Anhänge]

The present study represents an evaluation of the current knowledge of the caudal endoskeleton of basal fossil and extant teleosts and gives new information on the origin, development and homology of the elements of the caudal skeleton. One of the major problems is the lack of metamerization in the posterior region of the body that makes identification of elements and homology statements difficult. The definitions of preural region, ural region, and preural centrum 1 are analyzed. Other landmarks that facilitate the identification and homologization of certain caudal elements are also reviewed. New studies on the early development of the caudal skeleton of basal extant teleosts demonstrate that the ural region develops from an early polyural skeleton into a diural skeleton or into a compound terminal centrum in different ways in different teleosts. The two ural centra present in adult teleosts develop ontogenetically and phylogenetically from a polyural stage independently in different teleostean lineages origin. Thus, the two ural centra of the diural skeleton are not homologous across teleosts. Consequently, we propose to study the origin and composition of the ural region of different teleosts using the polyural terminology. This assumes a one-to-one relationship between ural centra and their respective hypaxial (e.g., ural 1/hypural 1; ural 2/hypural 2; ural 3/hypural 3) and epaxial elements. Polyural terminology facilitates interpretation of the composition of the two ural centra and their relationships to epaxial and hypaxial elements of the caudal fin. The compound terminal centrum (synonym: urostyle) present in most ostarioclupeomorphs (or otocephalans) and many euteleosts is currently assumed to be the result of a fusion involving preural centrum 1 and the first ural centrum. According to our studies based on day-to-day ontogenetic series, the compound terminal centrum is the result of an early fusion of preural centrum 1 with different ural centra in different teleosts. From the highest number of 13 hypurals found in the Early Jurassic †Pholidophorus bechei, a decreased number of 8 or 7 hypurals is observed in Late Jurassic elopiforms and 6 or fewer hypurals in extant teleosts. In most cases the reduction in number of hypurals has been interpreted as a fusion of elements, but this has not been shown ontogenetically. A complete series of true uroneurals occurs first in “true” teleosts (†Leptolepis coryphaenoides plus more advanced teleosts) at the base of the teleostean radiation. The homology of uroneurals is still not understood for most fossil and extant teleosts, with a reduction in number ranging from 7 to 3 to none in different extant teleostean lineages. In fossil basal “true” teleosts, the anterior-most uroneural seems to be a modification of ural neural arch 2 or 3, whereas the anterior-most uroneural is a modification of ural neural arch 4 in elopiforms, some osteoglossomorphs and salmonids. The origin and development of the pleurostyle (currently interpreted as a modified uroneural) in ostarioclupeomorphs remain unclear. The pleurostyle differs between groups, being chondral in some, but a membrane bone in others. “Uroneurals of a peculiar sort” develop as modified epaxial elements of preural as opposed to ural centra in fossil †pachycormiforms, some †aspidorhynchiforms and †’pholidophoriforms’. The homology of epurals is not fully understood for most basal teleosts. Epurals of basal teleosts are neural spines separated from neural arches. Basal teleosteomorphs and a few basal teleosts (and salmonids) possess simultaneously epurals derived from neural spines of both preural and ural centra. However, aspidorhynchiforms lack epurals. In †Leptolepis coryphaenoides plus more advanced teleosts the anterior-most epural corresponds to the neural spine of ural centrum 1, the second epural to ural centrum 2, and so on. In fossil and extant elopiforms, the three epurals correspond to ural centra 1–3 (polyural terminology), whereas in basal osteoglossomorphs the only epural present seems to belong to ural centrum 2 (polyural terminology). According to the present evidence, the origin of the one or two epurals present in ostario­clupeomorphs, as well as their homology, remains unknown.

Kelly J. IRWIN and Christopher FIELITZ: Ichthyodectiform fishes from the Late Cretaceous (Campanian) of Arkansas, USA
[S. 247–266, 12 Abbildungen, 2 Tabellen]

Several specimens of the ichthyodectiform fishes Xiphactinus audax and Saurocephalus cf. S. lanciformis are reported from the Upper Cretaceous (Campanian) Brownstown Marl and Ozan formations of southwestern Arkansas, U.S.A. Seven individuals of Xiphactinus, based on incomplete specimens, are represented by various elements: disarticulated skull bones, jaw fragments, pectoral fin-rays, or vertebrae. The circular vertebral centra are diagnostic for X. audax rather than X. vetus. The specimen of Saurocephalus consists of a three-dimensional skull, lacking much of the skull roof bones. It is identified as Saurocephalus based on the shape of the predentary bone. This specimen provides the first record of entopterygoid teeth in Saurocephalus. These specimens represent new geographic and geologic distribution records of these taxa from the western Gulf Coastal Plain, which biogeographically links records from the eastern Gulf Coastal Plain with those from the Western Interior Sea.

Alison M. MURRAY and Mark V. H. WILSON: Two new paraclupeid fishes (Clupeomorpha: Ellimmichthyiformes) from the Upper Cretaceous of Morocco
[S. 267–290, 8 Abbildungen (3 farbig), 2 Tabellen, 2 Anhänge]

A collection of fossil fishes from the Akrabou Formation of Morocco has provided a number of new species, including three members of the Ellimmichthyiformes. Two of these are here described in one genus and placed in the family Paraclupeidae. One, named here Thorectichthys marocensis gen. et sp. nov., is represented by numerous fairly well preserved specimens, but the second species, T. rhadinussp. nov., is represented by only three specimens, which are not well preserved. The third ellimmichthyiform from the Akrabou Formation, also represented by three specimens, is a member of the family Sorbinichthyidae. The Ellimmichthyiformes include species that have been found in a diversity of freshwater as well as estuarine or marginal marine habitats, from South and North America, the Mediterranean region and Asia. The Ellimmichthyiformes range from Neocomian (early Early Cretaceous) through Eocene in age, with the Moroccan material being probably early Turonian or possibly late Cenomanian in age, and from normal-salinity marine waters. The new paraclupeids, as well as a number of other recently described ellimmichthyiforms, are included in a new analysis of relationships based on previously documented osteological characters. The analysis indicates that the new genus Thorectichthys is sister to a clade containing Ellimma, Ellimmichthys, Rhombichthys, Paraclupea, Tycheroichthys, and Triplomystus.

Michael G. NEWBREY, Donald B. BRINKMAN, Dale A. WINKLER, Elizabeth A. FREEDMAN, Andrew G. NEUMAN, Denver W. FOWLER and Holly N. WOODWARD: Teleost centrum and jaw elements from the Upper Cretaceous Nemegt Formation (Campanian–Maastrichtian) of Mongolia and a re-identification of the fish centrum found with the theropod Raptorex kreigsteini
[S. 291–303, 6 Abbildungen]

Isolated centra and a premaxilla of a teleost from the Upper Cretaceous Nemegt Formation (Late Campanian–Early Maastrichtian) of Mongolia are described and aligned with the hiodontids and the Late Cretaceous teleost Coriops from North America. The atlas of the Nemegt taxon has an anterior articular surface with the dorsal half being subdivided into two flat articulator surfaces as in those of the hiodontids. In more posterior abdominal centra, the centrum is strongly constricted at the notochord foramen, the rib loosely articulates in a facet on the lateral wall of the centrum posterior to the parapophysis as in hiodontids, and parapophyses are fused to the centrum. Neural arch articular facets are small and round. Distinct mid-dorsal foramina are absent or small and poorly developed. A single stout premaxilla is relatively straight and has a low rounded dorsal margin on the posterior end. There are two rows of strong conical teeth and the tooth bases of the lateral row protrude laterally. The Nemegt centra are then used to re-identify a teleost centrum associated with the Asian theropod, Raptorex kreigsteini. Initially the fish centrum found with R. kreigsteini was assigned to Lycoptera. The stratigraphic range of Lycopteridae, ~120–135 Ma, was used to infer an age of deposition for the basal taxon Raptorex. Subsequently this centrum was re-identified as a clupeomorph centrum. However, centra of Lycoptera are mainly comprised of the chordacentrum surrounded by a very thin autocentrum, thus giving the appearance of being tubular with an unconstricted notochordal foramen; they are thin-walled, small (≤2 mm diameter), and may have a broad bar (presence depends on the species and ontogenetic development) extending the length of the centrum in lateral view. Parapophyses are not fused with the autocentrum and articulate with the centrum at large facets as in those of lower teleosts. Pleural ribs in Lycoptera articulate with the parapophyses. The fish centrum found with R. kreigsteini is of a higher teleost with a well-developed autocentrum strongly constricting the notochord, thereby giving the centrum an amphicoelous shape. This centrum has several aspects in common with the Nemegt Formation teleost centra: poorly developed mid-dorsal foramen; shape and position of the facets, where the arch articulates, being circular and located near the anterior end of the centrum; presence of short, fused parapophyses at the ventro-lateral corner of the centrum; lateral surface of the centrum bearing a series of foramina of small to moderate size that are generally organized into rows. Thus we reject the hypotheses that the fish centrum found with R. kreigsteini has affinities with the Lycopteridae or the Clupeomorpha and reassign the centrum to the hiodontids. The morphological characteristics of the fish centrum found with R. kreigsteini suggest a Late Cretaceous hiodontid-like taxon and thus its co-occurrence with Raptorex suggests that dinosaur is an Upper Cretaceous theropod.

Cesar R. L. AMARAL, Jesús ALVARADO-ORTEGA and Paulo M. BRITO: Sapperichthys gen. nov., a new gonorynchid from the Cenomanian of Chiapas, Mexico
[S. 305–323, 9 Abbildungen, 1 Anhang]

Sapperichthys gen. nov. is described herein based on new Cenomanian specimens from the Sierra Madre Formation, Chiapas, Mexico. This new gonorynchid exhibits several diagnostic characters of the Gonorynchiformes such as the absence of orbitosphenoid and basisphenoid, the anterior neural arches expanded in the lateral plane, and the presence of three sets of intermuscular bones; and of the Gonorynchidae such as the elongate and narrow frontal bone except in postorbital region and the presence of two patches of conical teeth. It is diagnosed as a valid taxon and a basal gonorynchid on the basis of characters such as the presence of a rounded opercle with a spiny posterior border; a smooth subopercle; a vertical oriented and triangular hyomandibular head; a wide metapterygoid; a V-shaped dentary, loosely articulated with the anguloarticular; medially expanded supraneurals, not in contact with each other, and loosely articulated with the neural arches; about 40 vertebrae; and 11 dorsal fin rays. This new taxon is the oldest record for the Gonorynchiformes in North and Central America, suggesting an origin of the Gonorynchidae probably related to the opening of the Mediterranean/Caribbean Tethys.

Matthew P. DAVIS, Gloria ARRATIA and Thomas M. KAISER: The first fossil shellear and its implications for the evolution and divergence of the Kneriidae (Teleostei: Gonorynchiformes)
[S. 325–362, 21 Abbildungen (12 farbig), 2 Tabellen, 2 Anhänge]

A new genus and species of shellear (Gonorynchiformes: Kneriidae), †Mahengichthys singidaensis, is described from the Eocene Mahenge deposits in Tanzania, Africa. This work represents the first record of a fossil kneriid gonorynchiform fish. Previously, all gonorynchiform fossils have been attributed to either the families Chanidae or Gonorynchidae, with some taxa incertae sedis. We explore the phylogenetic position of †Mahengichthys singidaensis within the gonorynchiforms, utilizing parsimony and maximum likelihood methodologies that incorporate both morphological and molecular data. Our results indicate that †Mahengichthys singidaensis is a kneriid gonorynchiform within the tribe Kneriini, which includes the extant genera Kneria and Parakneria. This phylogenetic work provides a framework for estimating the divergence times of the Kneriidae for the first time using Bayesian methodology with calibrations that include information regarding extinct kneriids. We infer that the exclusively freshwater family Kneriidae most likely diverged and diversified during the Cretaceous to Paleogene in Sub-Saharan Africa, following the continent’s separation from South America.

Michael G. NEWBREY, Alison M. MURRAY, Mark V. H. WILSON, Donald B. BRINKMAN and Andrew G. NEUMAN: A new species of the paracanthopterygian Xenyllion(Sphenocephaliformes) from the Mowry Formation (Cenomanian) of Utah, USA
[S. 363–384, 10 Abbildungen (3 farbig), 1 Tabelle]

A new species of Xenyllion (Sphenocephalidae) is described from the Upper Cretaceous (earliest Cenomanian) Mowry Formation of Utah, USA. The nearly complete, mostly articulated specimen represents a one-year-old individual and is about 38 mm in standard length. The specimen is included in Sphenocephaliformes because of the presence of a recurved spine on the posterodorsal extension of the opercle, large, widely-spaced spines on the preopercle, mandibular sensory canal enclosed in a bony tube, fine parallel ridges on the lateral face of the angular, and short ventral limb on the preopercle. The Utah specimen is a member of the genus Xenyllion because it lacks scales on the opercle, lacks an arch on the frontal bone, and lacks foreshortened vertebral centra. The new species differs from X. zonensis in six ways, including an opercle that has prominent ridges and spines on the ventrolateral margin, a broad rectangular subopercle that does not taper posterodorsally, and a cleithrum that is uniformly wide along its length and lacks a large posterodorsal lobate expansion. The new species shows that the diversity of Xenyllion is greater than previously thought and is comparable to that of the European Sphenocephalus from the Campanian. Xenyllion inhabited the Mowry Sea, suggesting that the genus originated in the Boreal Ocean and in a cool climate at or before the Albian/Cenomanian boundary.

Terry GRANDE, W. Calvin BORDEN and W. Leo SMITH: Limits and relationships of Paracanthopterygii: A molecular framework for evaluating past morphological hypotheses
[S. 385–418, 6 Abbildungen, 4 Anhänge]

Gadiforms and percopsiforms have historically been treated as prototypical or core paracanthopterygians. As such, they are the keys to unlocking the evolutionary history and limits of a revised Paracanthopterygii; therefore, we address the taxonomic compositions of gadiforms and percopsiforms and how they are related to each other and other putative basal acanthomorphs. We address these questions by first constructing a phylogenetic hypothesis based on multiple molecular loci. Both maximum likelihood and parsimony criteria strongly support a Paracanthopterygii comprised of Percopsiformes + [Zeiformes + (Stylephorus + Gadiformes)]. Polymixiids are sister to this clade. Polymixiids + paracanthopterygians are in turn sister to the acanthopterygians (batrachoidiforms, beryciforms, lophiiforms, ophidioids, percomorphs) in the parsimony analysis but sister to Acanthopterygii + Lampriformes (minus Stylephorus) in the likelihood analysis. Published morphological characters, putatively pertinent to paracanthopterygian systematics, were reviewed and evaluated by the direct examination of specimens. Results showed high congruence between the molecular tree and character-state distributions for many of the internal relationships. New interpretations of homologies of published characters are proposed based on topological and phylogenetic data.

W. Calvin BORDEN, Terry GRANDE and W. Leo SMITH: Comparative osteology and myology of the caudal fin in the Paracanthopterygii (Teleostei: Acanthomorpha)
[S. 419–455, 14 Abbildungen, 2 Anhänge]

There are no fewer than twenty phylogenetic hypotheses of basal acanthomorph relationships. Among basal acanthomorphs, the Paracanthopterygii have historically been one of the more difficult groups to characterize, leaving many systematists to question their composition and monophyly. Here we investigate the osteology and myology of the caudal fin of paracanthopterygians. We describe 26 characters (14 osteological, 12 myological) from Recent and fossil material and evaluated their congruence with a phylogenetic hypothesis [Polymixiiformes (Percopsiformes (Zeiformes (Gadiformes Stylephoriformes)))] derived from the analysis of DNA sequence data. Osteological characters support more basal nodes and nodes within zeiforms and percopsiforms. In contrast, myological characters reflected the unique caudal fin of gadiforms and stylephoriforms. Both types of characters revealed significant homoplasies when mapped onto the existing molecular hypothesis. Nonetheless, osteological homoplasy reflected the recurring trend among teleosts of simplification of the caudal skeleton. Myological homoplasy reflected in part the inclusion of fossil taxa and the unusual, but varied, states within gadiforms. Despite these issues and a general need for increased resolution of relationships within paracanthopterygian lineages, morphology of the caudal fin reasonably supported the revised relationships. Perhaps more importantly, it highlighted the significant work needed to place many fossil lineages accurately and to test hypotheses of homology.

Katia A. GONZÁLEZ-RODRÍGUEZ, Hans-Peter SCHULTZE and Gloria ARRATIA: Miniature armored acanthomorph teleosts from the Albian/Cenomanian (Cretaceous) of Mexico
[S. 457–487, 14 Abbildungen (9 farbig)]

Small, armoured teleosts in the Albian/Cenomanian of the Muhi Quarry near Zimapán, State of Hidalgo, Mexico, are described as “monocentrid-like” (beryciforms) and acanthomorph incertae sedis. Two new genera and species, †Handuichthys interopercularis gen. et sp. nov. and †Pseudomonocentris microspinosus gen. et sp. nov., are established. The two species are distinct from the acanthomorph incertae sedis †Dalgoichthys tropicalis gen. et sp. nov. by having a large interopercle, differences in shape of subopercle and infraorbitals 2 and 3, and arrangement of the body shields (irregular in †Handuichthys and †Pseudomonocentris, but distributed in characteristic longitudinal rows in † Dalgoichthys). †Handuichthys interopercularis gen. et sp. nov. and †Pseudomonocentris microspinosusgen. et sp. nov. are placed in a new family, †Pseudomonocentrididae. Members of the family †Pseudomonocentrididae are small fishes less than 6 cm maximum length, with large head, balloon-like body, and short and narrow caudal peduncle resembling extant pinecone fishes or monocentrids. †Pseudomonocentrids have a large opercle, a small and narrow subopercle posteroventral to the opercle, and a large interopercle, which is longer than the ventral margin of the preopercle. Strong pelvic and anal spines are present, whereas dorsal spines are absent. Head bones and body shields are ornamented with tubercles and bony ridges, and the body is covered with heavily ossified, overlapping shields, which are not arranged in well-defined horizontal or vertical rows. In contrast, the body of †Dalgoichthys gen. nov. is covered with heavily ossified, overlapping shields ordered in rows in similar fashion as extant agonids. †Dalgoichthys gen. nov. presents a curious mosaic of cottiform and scorpaeniform features such as a parietal [= postparietal] bone fused with the extrascapula that makes its identification problematic; therefore, the fish is interpreted as an acanthomorph incertae sedis, an assigment that should be revised when more specimens become available.

Yoshitaka YABUMOTO and Paulo M. BRITO: The second record of a mawsoniid coelacanth from the Lower Cretaceous Crato Formation, Araripe Basin, northeastern Brazil, with comments on the development of coelacanths
[S. 489–497, 5 Abbildungen (5 farbig), 1 Tabelle]

A well-preserved fossil coelacanth from the Lower Cretaceous Crato Formation in Araripe basin, northeast Brazil, is the second record of a coelacanth from this formation. The new specimen is slightly larger than the first one, with an estimated total length of about 100 mm. It is identified as Axelrodichthys araripensis MAISEY, 1986, based on the following features: the dorsal outline of the head is concave, the deepest portion of the lower jaw is located anteriorly, and the median extrascapular bone is present. The longer fin rays and the larger head as compared to those of adults are characteristics of juveniles of this species. The lung is already covered with thin, calcified plates at this stage. The toothed dermopalatine and ectopterygoid are described in this species for the first time. The scales have minute tubercles on the exposed area. The fact that the specimens of Axelrodichthys from the Crato Formation are juveniles as also are specimens of other species found in the Santana and the Crato formations led us to suggest paleoecological implications related to their reproductive biology.

Anne KEMP and Rodney W. BERRELL: Lungfish as environmental indicators
[S. 499–508, 5 Abbildungen]

Lungfish fossil material is widespread, and the records are almost continuous in some continents, from the time that lungfish first appeared. Lungfish live for a long time, and the dentition is never replaced during the life of the fish. Tooth plates, the parts most often preserved in lungfish, can provide information about how the fish lived, what it could have eaten, and how good the environment was. For many reasons, lungfish are good indicators of environmental health. However, analysis of the diseases present in fossil populations over time shows that the story is not positive for the future survival of the Australian lungfish. Mesozoic lungfish tooth plates show only a few examples of caries, and the range of diseases present in the dentitions of Cenozoic and living populations includes erosion, caries, abscesses, hyperplasia, parasitic invasion and osteopenia. Some lungfish tooth plates from Cenozoic environments show attrition, as do specimens from living lungfish, suggesting that the fish did not have enough food. Comparison of Mesozoic material with specimens from younger deposits suggests that the condition of lungfish populations and their environments has deteriorated over time.

Stephen L. CUMBAA, Charlie J. UNDERWOOD and Claudia J. SCHRÖDER-ADAMS: Paleoenvironments and Paleoecology of the Vertebrate Fauna from a Late Cretaceous Marine Bonebed, Canada
[S. 509–524, 5 Abbildungen (2 farbig), 1 Tabelle]

Bonebeds – concentrations of bioclastic debris of vertebrates in geological strata – can accumulate under a variety of conditions. They are common in marine deposits of the Late Cretaceous Western Interior Seaway of North America, and are often characterized as lag deposits. In general, these deposits represent unknown periods of accumulation and contain a mélange of taxa, possibly transported from a variety of habitats. As such, the contents of these marine bonebeds are often considered less useful for studies of paleoecology and paleoenvironments than are fossils recovered from rock units that represent continuous sedimentary deposition within one or more contiguous paleoenvironments. We examined the fossil contents of one particularly rich marine bonebed of “middle” Cenomanian age to determine if useful conclusions can be drawn with respect to the habitats and probable interactions of its pre-depositional fauna. This bonebed occurs as discontinuous lenses in shales of the upper part of the Belle Fourche Member of the Ashville Formation in the Pasquia Hills of Saskatchewan, Canada.

Acid preparation of these lenses revealed an assemblage containing: 20 chondrichthyan taxa: a chimaeriform, hybodontiforms, diverse lamniforms and rare rajiforms; 15 actinopterygian taxa: a caturid, pycnodonts, an aspidorhynchid, a pachycormid, a plethodid, ichthyodectids, pachyrhizodontids, an albulid, a putative salmoniform, enchodontids, and an acanthomorph; and nine tetrapods including turtles, pliosaurs and elasmosaurs, four marine bird taxa, a terrestrial bird, and a lizard. Evaluation of probable habitats of the fish fossils reveals many pelagic forms, but a sparse nectobenthic fauna. Only one or two genera of those identified are considered to be euryhaline, and there are no obligate freshwater forms. The overwhelming majority of taxa identified are fully marine. Inferred feeding strategies for fish taxa include several durophagous forms including Ptychodus, a pycnodont and an albulid, with most other taxa, including the most abundant shark species (lamniforms) and osteichthyans (Enchodus) appearing to have been active predators with piercing dentitions. There are also predators/scavengers with cutting dentitions (anacoracid sharks) and a probable planktivore (Cretomanta). Interpretation of the taphonomy and faunal content indicates that the bonebed accumulated near shore over a period up to tens of thousands of years and was largely composed of bioclastic detritus from shallow, contiguous habitats, with some input from a deeper, anoxic shelf assemblage.

Alison M. MURRAY, Mark V. H. WILSON, Stacey GIBB and Brian D. E. CHATTERTON: Additions to the Late Cretaceous (Cenomanian/Turonian) actinopterygian fauna from the Agoult locality, Akrabou Formation, Morocco, and comments on the palaeoenvironment
[S. 525–548, 17 Abbildungen (1 farbig)]

Actinopterygian fishes recovered from southeastern Morocco in 2006–2009 indicate the presence in the area of a number of forms not previously documented for northern Africa. The fauna is generally similar at the familial level to that of marine Cenomanian and Turonian sites long known from Lebanon and from the Jebel Tselfat locality in northern Africa, but includes elements (e.g., Macrosemiidae) that had not previously been reported from deposits of this age in the Tethys basin. Some taxa previously reported from this site are here reidentified or identified more precisely. The fauna represented includes a macrosemiid (Agoultichthys chattertoni) and two other holosteans, at least three different ellimmichthyiforms (two paraclupeids and the sorbinichthyid Sorbinichthys africanus), two dercetids, one Teleostei incertae sedis, the clupavid Lusitanichthys, at least two pycnodontiforms, and three or more species of acanthomorph. Some of these taxa are essentially circum-Tethyan, such as the Dercetidae; however, others, such as the Paraclupeidae, are known from Cretaceous deposits worldwide, including Mexico, Europe, Canada, and China. Increased collecting and documentation of the area indicates that the small ichthyofauna reported from Oued Daoura, is likely from the same locality or one very close (in area or stratum), but we retain the name “Agoult locality”. The specimens reported here were collected, or purchased at the locality, by the authors, and are thus from a known outcrop.

Helmut TISCHLINGER and Gloria ARRATIA: Ultraviolet light as a tool for investigating Mesozoic fishes, with a focus on the ichthyofauna of the Solnhofen archipelago
[S. 549–560, 2 Abbildungen (2 farbig)]

A historical review of the discovery and use of ultraviolet light (UV light) in studies of fossils is provided together with a presentation of UV techniques currently used in fossil invertebrate and tetrapod research. Advantages of the use of UV techniques are presented and discussed in detail, as are certain hazards that may derive from the use of these techniques when strict recommendations are not followed. While UV techniques have proven to be important in revealing sutures, other articulations, hidden bones, and/or the presence of soft tissues in fossil tetrapods and invertebrates, they have been scarcely used in fish research. We provide here a few examples documenting the importance of UV techniques in understanding early ontogenetic stages of development, in providing and/or clarifying some morphological characters, and even revealing unexpected new information in fishes (e.g., squamation and formation of vertebral elements in aspidorhynchids; ossification of bones in teleosts). A list of Mesozoic deposits that have given satisfactory results when their fossils have been studied under UV techniques is presented.

Mesozoic Fishes meetings are designed to bring together researchers, students, and other interested persons every four years to present research and to foster discussion and collaboration about fossil fishes of the Mesozoic. The meetings often also include presentations on related subjects such as early Cenozoic fishes. The first four meetings were all held in Europe (Eichstätt, Germany, 1993; Buckow (near Berlin), Germany, 1997; Serpiano (near Lugano), Switzerland, 2001; Miraflores de la Sierra (near Madrid), Spain, 2005). Therefore, it was a bold and exciting departure for our Mexican hosts to invite us all to Saltillo, Coahuila state, Mexico, for the 5th Mesozoic Fishes meeting, which was originally planned for August/September 2009. This would be the first Mesozoic Fishes meeting to be held outside of Europe.

The year 2009 proved to be a difficult one for the organization of the meeting for reasons beyond their control. One issue might have been news reports about drug-related violence in northern Mexico, leading potential attendees to be nervous about travel to the area. However, a bigger problem was an outbreak of so-called “swine flu” or “swine influenza” which was initially recognized in Mexico in April 2009 and, despite its name, it was spread from human to human, and later became a pandemic. Government health agencies recommended against travel to Mexico that spring and summer. In the end, there were too few registrants for the meeting to be held in 2009. The organizers took the difficult decision to cancel the meeting for 2009 and to organize it instead for the summer of 2010. This decision involved many difficulties including re-booking of hotels, meeting venues, social events, and excursions, and re-applying for financial and logistical support from a variety of Mexican government and academic institutions.

Fortunately for the Mesozoic Fishes community, and especially for those of us who attended, the organizers were able to accomplish all of the re-scheduling, and to invite us to Mesozoic Fishes 5 in Saltillo during August 2-7, 2010. By that time, conditions were much better for travel, and the number of registrants was larger than the previous year.

The meetings in Saltillo were held at the Museo del Desierto, a modern and beautiful facility with excellent exhibits about the fauna and flora of the region and featuring attractive gardens and beautiful views of the city and the surrounding valley and mountains. The official hosts included the Secretaría de Educación y Cultura del Estado de Coahuila, the Museo del Desierto itself in Saltillo, the Universidad Nacional Autónoma de México - Instituto de Geología, and the Museo de Paleontología of the Universidad Autónoma del Estado de Hidalgo. The organizing committee included María del Rosario Gómez-Núñez, Katia A. González-Rodríguez, and Jesús Alvarado-Ortega.

One of the most exciting things about the conference was meeting the large number of Mexican colleagues and students, and learning about their work and the very interesting fossil sites that are being studied in that country. The proportion of young scientists from Mexico and from elsewhere in Latin America was much higher than we have seen elsewhere, a fact that bodes well for the future of paleoichthyology in Central and South America. Mexican colleagues dedicated the meeting to the memory of the late Shelton P. Applegate, who stimulated research, collections, and graduate education based on Mexican fossil fishes over several decades. Shelley attended previous Mesozoic Fishes meetings, and died in 2005.

Presentations at the meeting were organized into five days of oral and poster sessions concerning fish taxa ranging taxonomically from chondrichthyans to teleosts and fossil assemblages ranging in age from Triassic to Cenozoic. Many important discoveries were announced and discussed, new research techniques were applied, and synthetic reviews of fossil sites were presented. The present volume is based largely on work that was presented at Mesozoic Fishes 5 in Saltillo, with additional contributions relevant to the theme of Mesozoic Fishes.

Special events included the opening of a new exhibition of Mexican fossil fishes at the Museo del Desierto; many of the fishes in the exhibition were the subject of presentations during the meeting. A memorable group dinner where we were entertained by a Mariachi band was held in a nearby restaurant. Excursions included a city tour with a visit to the central marketplace and a visit to the “Museum of the Dead” where we learned the meaning of being “like water for chocolate”, which means being exactly or perfectly ready. The field trip on the last day to Late Cretaceous sites in Coahuila state included visits to local museums and localities, a walk in the desert at Porvenir de Jalpa to view dinosaur trackways, a chance to see petroglyphs at Narihua, and a farewell banquet hosted by the people of the town General Cepeda that included musical and dance performances, followed by general dancing.

The meeting as a whole was very well organized, and participants felt warmly welcomed by the their Mexican hosts. We left Saltillo with a new appreciation of the exciting work being done in Mexico, with much to think about scientifically, with new opportunities for collaboration, and with new friends and renewed old friendships.

The Editors

ADAMS, Colin E., Scottish Centre for Ecology & the Natural Environment, University of Glasgow, Glasgow, Scotland.

ALVARADO-ORTEGA, Jesús, Instituto de Geologia, Universidad Nacional Autónoma de México; Ciudad Universitaria, Delegación, Coyoacán, México, México.

AMARAL, Cesar R. L., Instituto de Biologia Roberto Alcântara Gomes, Universidade do Estado do Rio de Janeiro, São Francisco Xavier, Maracanã, RJ, Brazil.

ARRATIA, Gloria, Natural History Museum and Biodiversity Institute, The University of Kansas, Dyche Hall, Lawrence, Kansas, U.S.A.

BERRELL, Rodney W., Macquarie University, Sydney, Australia.

BORDEN, W. Calvin, Department of Biology, Loyola University Chicago, Chicago, Illinois U.S.A.

BRINKMAN, Donald B., Royal Tyrrell Museum of Palaeontology, Drumheller, Alberta, Canada.

BRITO, Paulo M., Instituto de Biologia Roberto Alcântara Gomes, Universidade do Estado do Rio de Janeiro, São Francisco Xavier, Maracanã, RJ, Brazil.

CHALLANDS, Thomas James, School of Geosciences, Grant Institute of Earth Sciences, University of Edinburgh, Edinburgh, Scotland.

CHATTERTON, Brian D. E., Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, Canada.

CIONE, Alberto Luis, División Paleontología Vertebrados, Facultad de Ciencias Naturales y Museo, Universidad Nacional de La Plata, La Plata, Argentina.

CUMBAA, Stephen L., Palaeobiology, Canadian Museum of Nature, Ottawa, Ontario, Canada.

DAVIS, Matthew P., The Field Museum, Department of Zoology, Chicago, Illinois, USA.

ESPINOSA-ARRUBARRENA, Luis, Museo de Geología. Universidad Nacional Autónoma de Mexico.

FIELITZ, Christopher, Emory & Henry College, Emory, Virginia, U.S.A.

FOWLER, Denver W., Museum of the Rockies, and Department of Earth Sciences, Montana State University, Bozeman, U.S.A.

FREEDMAN, Elizabeth A., Museum of the Rockies, and Department of Earth Sciences, Montana State University, Bozeman, U.S.A.

GIBB, Stacey, Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, Canada.

GONZÁLEZ-BARBA, Gerardo, Museo de Historia Natural, Universidad Autónoma de Baja California Sur, La Paz, B.C.S., Mexico.

GONZÁLEZ-RODRÍGUEZ, Katia A., Instituto de Ciencias Básicas e Ingeniería, Museo de Paleontología, Centro de Investigaciones Biológicas, Universidad Autónoma del Estado de Hidalgo, Mineral de la Reforma, Hidalgo, Mexico.

GOUIRIC-CAVALLI, Soledad, División Paleontología Vertebrados, Facultad de Ciencias Naturales y Museo, Universidad Nacional de La Plata, La Plata, Argentina.

GRANDE, Terry, Department of Biology, Loyola University Chicago, Chicago, Illinois, U.S.A.

IRVIN, Kelly J., Arkansas Game & Fish Commission, Benton, Arkansas, U.S.A.

KAISER, Thomas, Zoological Institute and Museum, University of Hamburg, Hamburg, Germany.

KEMP, Anne, Australian Rivers Institute, Nathan Campus, Griffith University, Brisbane, Queensland, Australia.

LISTON, Jeff, Department of Natural Sciences, National Museums Scotland, Edinburgh, Scotland;
School of Earth Sciences, Wills Memorial Building, Queens Road, University of Bristol, England;
Division of Environmental & Evolutionary Biology, School of Life Sciences, College of Medical Veterinary & Life Sciences, University of Glasgow, Glasgow, Scotland.

MARTÍN-ABAD, Hugo, Unidad de Paleontología, Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, Cantoblanco, Madrid, Spain.

MICKLE, Kathryn, University of Kansas, Biodiversity Research Institute, Lawrence, Kansas, U.S.A.;
Rockhurst University, Biology Department, St. Ignatius Science Building, Kansas City, Missouri, U.S.A.

MURRAY, Alison M., Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada.

NEUMAN, Andrew G., Royal Tyrrell Museum of Palaeontology, Drumheller, Alberta, Canada.

NEWBREY, Michael G., Royal Tyrrell Museum of Palaeontology, Drumheller, Alberta, Canada;
Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada.

POYATO-ARIZA, Francisco José, Unidad de Paleontología, Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, Cantoblanco, Madrid, Spain.

SCHRÖDER-ADAMS, Claudia J., Department of Earth Sciences, Carleton University, Ottawa, Ontario, Canada.

SCHULTZE, Hans-Peter, Natural History Museum and Biodiversity Institute, The University of Kansas, Dyche Hall, Lawrence, Kansas, U.S.A.

SMITH, W. Leo, Division of Fishes, Field Museum of Natural History, Chicago, Illinois, U.S.A.

TISCHLINGER, Helmut, Stammham, Germany.

UNDERWOOD, Charlie J., School of Earth Sciences, Birkbeck College, London, UK.

WILSON, Mark V. H., Department of Biological Sciences, University of Alberta, Edmonton, Canada.

WINKLER, Dale A., Department of Earth Sciences, Southern Methodist University, Dallas, Texas, U.S.A.

WOODWARD, Holly N., Museum of the Rockies, and Department of Earth Sciences, Montana State University, Bozeman, U.S.A.

YABUMOTO, Yoshitaka, Department of Natural History, Kitakyushu Museum of Natural History and Human History, Kitakyushu, Fukuoka, Japan.