†Xiphiorhynchoides haeringensis, a new genus and species of Billfish – Paleontology of the Oligocene Ashley and Chandler Bridge Formations of South Carolina

FIERSTINE, Harry L. & Friedrich H. PFEIL:
†Xiphiorhynchoides haeringensis, a new genus and species of Billfish (Perciformes: Xiphioidei: Xiphiidae: †Xiphiorhynchinae) from Bad Häring, Tyrol, Austria, Lower Oligocene (NP 22)

In den küstennahen, marinen Tiefwassersedimenten der Paisslberg-Formation, Unteroligozän (Rupelium, NP 22) wurde im Bergpeterl-Bruch von Bad Häring, Tirol, 1983 ein fast vollständiges, gut erhaltenes Skelett (Schädel und vorderer Teil des Körpers) eines großen Schwertfisches gefunden, der Beziehungen zur Gattung †Xiphiorhynchus aufweist. Es ist das bisher am vollständigsten erhaltene Exemplar der Unterfamilie †Xiphiorhynchinae. Sein Rostrum zeigt viele Eigenheiten von †Xiphiorhynchus: Es ist aufgebaut aus paarigen Praemaxillae, die distal miteinander verbunden sind, es hat ein internes Kanalsystem mit einem zentralen und zwei Paaren lateraler Kanäle und seine ventrale Oberfläche ist mit zahlreichen winzigen villiformen Zähnchen bedeckt. Die folgenden Merkmale waren bisher bei †Xiphiorhynchus noch nicht bekannt: der Unterkiefer, der ebenso lang wie der Oberkiefer und mit der Symphyse verschmolzen ist, die großen Hyoidknochen, das vollständige Suspensorium, Brustflossen und Brustgürtel, Dorsal- und Analflossen, bis zu elf artikulierende Wirbel. Nicht lokalisieren konnten wir die Beckenflossen, Maxillae, Nasalia, Praenasalia und Schuppen.
Das Neurocranium unterscheidet sich von anderen der Gattung †Xiphiorhynchus zugeordneten durch sein verlängertes Siebbein (os ethmoidale) und das offensichtliche Fehlen von Nasalia. Zusätzlich sind alle Elemente des Brustgürtels in dorso-ventraler Ebene ausgerichtet. Das Exemplar von Bad Häring unterscheidet sich damit ausreichend von †Xiphiorhynchus, sodass wir es hier als neue Gattung und Art †Xiphiorhynchoides haeringensis beschreiben.

FIERSTINE, Harry L. & Robert E. WEEMS:
Paleontology of the Oligocene Ashley and Chandler Bridge Formations of South Carolina, 4: Analysis and New Records of Billfishes (Perciformes: Xiphioidei)

The billfish fauna of the Ashley and Chandler Bridge formations consists of three species of †Aglyptorhynchus [†A. robustus (LEIDY, 1860), †A. palmeri n. sp., and †A. alsandersi n. sp.] and one species of †Xiphiorhynchus [†X. rotundus (WOODWARD, 1901), plus numerous specimens identifiable either to †Aglyptorhynchus sp., †Xiphiorhynchus sp., or Istiophoridae genus and species indeterminate. Numerous morphological features are described for the first time, including the maxilla and opisthocelous first vertebra of †A. robustus, the anterior neurocranium and suspensorium of †A. palmeri, and a series of middle precaudal and posterior caudal vertebrae identified as †Aglyptorhynchus sp. Based on the ball and socket articulation of the first vertebra and occipital condyle, and the probable articulation of the maxilla to the neurocranium and angulo-articular, it is postulated that †Aglyptorhynchus had a mobile rostrum to increase its gape and a mobile head that may have been useful in prey capture. The middle precaudals have elongated and flattened neural spines, but they are very thin and probably did little to stiffen the vertebral column. The caudal fin skeleton is composed of three vertebrae (preurals 2 and 3, and hypural) with the preural 2 having a deep groove for articulation with a stout hemal spine. The hypural is a single fused structure with a well-developed hypurapophysis and deep grooves for overlapping caudal fin rays.
†Aglyptorhynchus is assigned to the Family †Palaeorhynchidae BLAINVILLE, 1818, partly because it shares with †Palaeorhynchus BLAINVILLE, 1818, the unusual feature of a downturned flange on the maxilla. Because detailed morphology of most individual bones of †Palaeorhynchus is unknown, †Aglyptorhynchus is separated from †Palaeorhynchus in the new subfamily †Aglyptorhynchinae.
The remains of †Xiphiorhynchus in the Ashley and Chandler Bridge formations demonstrate that the genus was probably represented by more than one species in the late Oligocene of North America, that additional specimens of †X. rotundus were present and the length of some vertebrae indicate xiphiorhynchins grew to a large size that rivals or exceeds the largest recorded size of the extant swordfish (Xiphias LINNAEUS, 1758). The presence of an istiophorid in an Oligocene deposit is noteworthy because no other specimen that has been unequivocally identified as an istiophorid has ever been found in a deposit older than middle Miocene.
No differences were observed between the billfish fauna of the Ashley and Chandler Bridge formations, in spite of the fact that the former is considered to be about 2 Ma older and was deposited in a middle-outer continental shelf environment, whereas the Chandler Bridge Formation was deposited in a nearshore, possibly lagoonal setting. The presence of †Aglyptorhynchus and †Xiphiorhynchus on both sides of the Atlantic Ocean and in the Tethys Seaway supports the hypothesis that a single North Atlantic-Tethys biogeographic province may have existed during the early Tertiary.