Memoirs of the Queensland Museum | Nature 59 © Queensland Museum 2015 PO Box 3300, South Brisbane 4101, Australia Phone 06 7 3840 7555 Fax 06 7 3846 1226 Email [email protected] Website www.qm.qld.gov.au National Library of Australia card number ISSN 2204-1478 (Online) ISSN 0079-8835 (Print) NOTE Papers published in this volume and in all previous volumes of the Memoirs of the Queensland Museum may be reproduced for scientific research, individual study or other educational purposes. Properly acknowledged quotations may be made but queries regarding the republication of any papers should be addressed to the Director. Hard copies of the journal can be purchased from the Queensland Museum Shop or are freely available online through the museum website. A Guide to Authors is displayed at the Queensland Museum web site www.qm.qld.gov.au A Queensland Government Project Typeset at the Queensland Museum Predation of the Early Cretaceous (Late Albian) pachycormiform, Australopachycormus hurleyi Kear, in Queensland’s Eromanga Basin Alan BARTHOLOMAI Director Emeritus, Queensland Museum, PO Box 3300, South Brisbane, Qld 4101, Australia. Citation: Bartholomai, A. 2015. Predation of the Early Cretaceous (Late Albian) pachycormiform, Australopachycormus hurleyi Kear, in Queensland’s Eromanga Basin. Memoirs of the Queensland Museum – Nature 59: 245–255. Brisbane. ISSN 2204-1478 (Online) ISSN 0079-8835 (Print): Accepted 18 Dec 2014. First published online: 30 November 2015. http://dx.doi.org/10.17082/j.2204-1478.59.2015.2014-04 LSID - urn:lsid:zoobank.org:pub:D351FC80-BDBA-47C6-BEB4-1A9C0A2FB4D0 ABSTRACT Additional remains of the marine pachycormiform fish, Australopachycormus hurleyi Kear, 2007, have been located in collections of the Queensland Museum from the Early Cretaceous (Late Albian) Toolebuc Formation of the Eromanga Basin, near Boulia in central western Queensland. The specimens significantly extend knowledge of the neurocranium, especially relating to the morphology of the orbital area, maxilla and mandible. The additional specimens show evidence of predation, with one possibly also having been regurgitated in a partially digested state. Australopachycormus hurleyi; neopterygian; pachycormiform; Early Cretaceous (Late Albian); Eromanga Basin; Toolebuc Formation. Investigation of collections of fossil actinop­ (2013) from near Richmond in the north of the terygian fishes in the Queensland Museum, both Basin, also from the Toolebuc Formation. in Brisbane and in its material loaned to the The Toolebuc Formation is a thin, organic Stonehouse Museum in Boulia, central western Queensland, has revealed the presence of rich unit, generally 20­45 m thick, that includes two additional neurocranial specimens of coquinitic limestone and shales (including the pachycormiform, Australopachycormus oil and kerigenous shales). Cook et al. (2013) hurleyi, Kear, 2007. These not only provide indicate that the Formation was deposited in additional morphological detail to that a layered epeiric sea, with dysoxic to anoxic outlined in Kear (2007) but also exhibit details benthic conditions. Henderson (2004) showed of preservation that help interpret their that the Formation contained shell beds in taphonomy. Currently known material of A. response to benthic oxygen fluctuations during hurleyi, including the holotype, QMF52641, a maximum deepening event. Many of the has mostly come from the marine Toolebuc fossil vertebrates from near Boulia have been Formation of Early Cretaceous (Late Albian) collected as isolated neurocrania or partial age, from the poorly exposed western rim of skeletons in calcareous concretions that have the Eromanga Basin near Boulia, within the been concentrated and exposed on the soil Great Artesian Superbasin, defined by Jell et surface by physical factors, with little or no al. (2013). Only an isolated rostrodermethmoid evidence of lateral transport. This is the case has been identified by Wretman and Kear with the current specimens. However, in recent Memoirs of the Queensland Museum | Nature 2015 59 www.qm.qld.gov.au 245 Bartholomai, A. years, more complete skeletons particularly of acetic acid prepared neurocranium and a coloured large reptiles have been found. fibre glass cast of the specimen prior to acetic acid preparation. The specimen was collected 15 miles Preparation of the specimens involved (ca. 24 km) north of ‘Springvale’ Station, NE of mechanical and acetic acid techniques. Boulia, CWQ. Age and Formation. From the marine Toolebuc Abbreviations Formation of Early Cretaceous (Late Albian) age. bc .......................... brain case cfct ............... compression fracture Description. The following descriptive notes cdk ......................coronoid tusk augment the original description of Australopachycormus hurleyi by Kear (2007). co ...........................coronoid Measurements for the specimens are presented den...........................dentary in the Appendix. dt ....................... dentary teeth dpal . dermopalatine The cranial roof is obtusely angular across ecp ......................ectopterygoid the dermopterotic­parietal area, becoming broadly convex across the back of the orbits fr..............................frontal and narrowing to a more tightly dorsally ga .................... gill arch element convex cross section anteriorly; no fronto­ gr ..........................gill rakers parietal boss appears present; the anterodorsal ha ..................hyoid arch element neurocranial surface slopes posteriorly at a low hm .................... hyomandibular angle to the horizontal, then bends slightly le ......................lateral ethmoid dorsally above the brain case. The posterior mx ............................maxilla of the neurocranium has suffered bone loss in pmx . .premaxilla QMF10913 (Fig. 1A­D) making it difficult to pa ............................ parietal identify most individual elements of the brain par ......................parasphenoid case. The brain case appears to have been almost pro­op ............... prootic­opisthotic fully ossified. Posteriorly, only dorsolateral surface bone remains. The lateral margin of qu...........................quadrate the dermopterotic is damaged by conical, rder ................rostrodermethmoid compaction fracturing and compression into the sc pl . sclerotic plate post­temporal fossa. The dermosphenotic forms sph­pts­obs.....sphenotic­pterosphenoid much of the dorsal margin of the orbit and is orbitosphenoid attenuated anteriorly. The hyomandibular facet ve .......................vertebral arch exhibits local, dorsal compressed fracturing into the base of the post­temporal fossa. Other isolated, CLASS ACTINOPTERYGII circular, pressure fractures are also evident on the parasphenoid. The posterior portion of SUBCLASS NEOPTERYGII the anterior semi­circular canal is exposed in dorsal view. Laterally, the subtemporal fossa is insignificant. ORDER PACHYCORMIFORMES The orbit is best preserved in QMF10913 Australopachycormus hurleyi Kear, 2007 (Fig. 1A) but neurocranial elements within (Figs 1–4) the orbit are mostly fractured and somewhat displaced on the right side. Very eroded and Australopachycormus hurleyi Kear, 2007: 1033–8. often fractured elements are exposed on the Material Examined. QMF52641, holotype (see Kear right side of QMF49220. The eye was large (see 2007). QMF49220, an incomplete skull and a plaster cast of the specimen before preparation. The specimen Appendix) and was supported by two, heavy is from ‘Lorna Downs’ Station (at 23° 22.127’ S and 140° sclerotic plates joined dorsally and ventrally, with 11.858’ E) near Boulia, CWQ. QMF10913, a partial each expanded mesially and transversely; the 246 Memoirs of the Queensland Museum | Nature 2015 59 Australopachycormus hurleyi Kear FIG. 1. Australopachycormus hurleyi Kear, 2007, specimen QMF10913; A, left lateral view of partial skull showing conical compression fractures along and below dermopterotic margin and large sclerotic plates; B, right lateral view showing displaced lateral ethmoid, united sphenotic­pterosphenoid­ orbitosphenoid and lack of defined junctions in braincase; C, dorsal view showing enlarged parietals and displaced but little corrosion of lateral ethmoid and united sphenotic­pterosphenoid­orbitosphenoid and arched dorsal surface of parasphenoid; and D, ventral view showing broad parasphenoid with several conical compression fractures. Scale bar = 1 cm. Memoirs of the Queensland Museum | Nature 2015 59 247 Bartholomai, A. plates are gently convex externally and gently above a smoothly concave outer surface that is concave internally. The surface of each plate is overlain ventrally by the upper margin of the ornamented over the outer moiety by very fine, pterosphenoid. The pterosphenoid is small, reticulating ridges, especially ventrally. penetrated anteriorly by a large optic fenestra. A foramen for the trochlear nerve penetrates the The lateral ethmoid is large and complex in bone above the optic fenestra. Internally, the QMF10913 (Fig. 4A) but is corroded in QMF49220 pterosphenoid contributes to the base of the (Fig. 4B). The anterior is poorly preserved in both braincase. The orbitosphenoid appears to be the specimens examined. The posterior surface is largest of the bones. It internally contributes to curved, smooth and expanded medially, forming the anterior of the cranial cavity and externally the anterior border of the orbit; it expands provides the smoothly concave upper wall of dorsally and curves posteriorly to broadly the orbit; it is separated