Ganawamaya acris Cooke 1992
Creators: name: Butler, Kaylene
name: Travouillon, Kenny J.
name: Price, Gilbert J.
name: Archer, Michael
name: Hand, Suzanne J.
Publisher: name: Zenodo
Year: 2018
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Mammalia
Diprotodontia
Balbaridae
Ganawamaya
Ganawamaya acris

description: Ganawamaya acris Cooke, 1992
Figures 1–2
v* 1992 Ganawamaya ornata Cooke, p. 202, figs. 1, 3.
Holotype. QM F16840, right dentary with i1, p3 and m1–m4 from RSO Site, Riversleigh WHA, northwestern Queensland, Australia (Cooke, 1992).
Referred Specimens. Boid Site: QM F24693, right dentary with p3, m1–m2, broken m3–m4. Camel Sputum Site: QM F58648, left maxilla with P3, M1– M4; QM F16841, right maxilla with P3, M1–M4; QM F19677, left maxilla with M2–M3; QM F19693, right maxilla with broken M1, M2–M4; QM F19862, left maxilla with P3, M1; QM F19901, right dentary with p3, m2–m4; QM F19969, right dentary with m3; QM F19970, left dentary with m2–m4; QM F19981, left maxilla with M2–M3; QM F20161, left maxilla with M1–M4; QM F20286, right maxilla with M3– M4; QM F20523, left maxilla with P3, M1–M4; QM F20617, left maxilla with P3, M1; QM F20618, left maxilla with M1–M4; QM F23476, right maxilla with P3, M1; QM F23485, right maxilla with M2–M3; QM F23485, right maxilla with M2–M3; QM F24189, right maxilla with broken M1, M2, broken M3. Creaser’s Ramparts Site: QM F20365, right dentary with i1, p3, m1–m4; QM F30870, left dentary with i1, p2, dp3, m1; QM F23820, right maxilla with M2–M4; QM F30274, right maxilla with P3, M1–4. Gag Site: QM F58649, partial left dentary with m1–m2. Inabeyance Site: QM F58650, right p3; QM F24514, left dentary with i1, p3, broken m1–m2, m3–m4. Judith’s Horizontalis Site: QM F58651, left maxilla with P3, M1–M4. Neville's Garden Site: QM F13090, right maxilla with M2–M4; QM F19879, right dentary with m1–m4; QM F19880, left dentary with m3, m 4 in crypt; QM F24186, left dentary with p3, m1; QM F24222, left dentary with m1–m3. Price is Right Site: QM F58652, left dentary with i1, p3, m1–m2, m4; QM F58653, left dentary with p3, m1–m4; QM F58654, right dentary with p3, m1–m3; QM F58655, left p3 cap. RSO: QM F20033, left dentary with dp3, unerupted p3, m3. Upper Site: QM F58656, left maxilla with P3, M1–M4; QM F19618, left maxilla with M2; QM F19625, right m2; QM F19639, right dentary with m1 and unerupted p3; QM F19661, right m1 and m2; QM F19665, right dentary with m3–m4; QM F19684, right maxilla with P3, M1; QM F19686, right maxilla with dP3, unerupted P3, M1– M2; QM F19840, palate with left M1–M4 and right M2–M4; QM F19884, right maxilla with M1, QM F19927, left maxilla with M3; QM F19944, right dentary with m1–m3; QM F19946, right M2,; QM F20192, right dentary with m2–m3; QM F20280, right maxilla with M1; QM F20292, right dentary with m1; QM F20296, right maxilla with M2–M4. Wayne's Wok Site: QM F58657, right dentary with p3; QM F57789, right dentary with m1–m3; QM F58659, right dentary with p2, dp3, unerupted p3, m3; QM F16839, right dentary with p3, m1–m3; QM F16842, left dentary with i1, p3; QM F19577, cranium with left P3, M1–M3; QM F19596; right dentary with p2, dp3, unerupted p3; QM F19821, right maxilla with M1–M4; QM F19846, left dentary with m4; QM F19899, right dentary with i1, dp3, unerupted p3, m1, m3; QM F19920, right maxilla with partial M1–M4; QM F19935, right maxilla with M1–M2; QM F20563, right dentary with m1; QM F24192, right maxilla with M2–M4; QM F31461, cranium with left P3, M1–M4 and right M1–M4; QM F36412, right maxilla with P3, M1–M3; QM F57788, left m4; QM F57790, right dentary with i1, p3, m1–m4.
The following specimens are referred based on casts of the original specimen: Basal Conglomerate, Leaf Locality, Wipajiri Formation, Tirari Desert, Lake Eyre Basin, South Australia: UCMP 88204, right dentary with p3, m1–m4; UCMP 88212, left maxilla with M2–M3.
Emended species diagnosis. Ganawamaya acris differs from all other species of Ganawamaya in having the following unique combination of features: masseteric process of the maxilla with small rounded eminence; well-developed sulcus on the anterior extremity of the zygomatic arch; distinct process on the ectotympanic; large zygomatic epitympanic sinus with thin medial wall; large mastoid foramen on mastoid/squamosal suture; well-developed anterior cingulum on M1; less well-defined posthypocristid on m1 and m2 and no posthypocristid on m4; more prominent paraconid on m1; large and sinuous i1 with dorsal and ventral enamel flanges; no marked convexities on the lateral margins of the interloph valley of lower molars; no hypoconulid on lower molars; poorly developed anterior cingulum on M1; stylar cusp C less prominent and connected to postparacrista on M1; and larger molar size; no additional cuspid on the posterior end of the p3 below the occlusal margin.
Description
Cranial morphology described here is based on QM F31461 (Figures 1, 2). This cranium has been transected through the splanchnocranium suggesting that either the anterior portion was inadvertently separated in the field at the time of collection or was destroyed during the fossilization process. No specimens examined appear to represent the anterior portion of this cranium.
Maxilla and Palatine. No distinct masseteric process is evident. However, there is a small eminence in place of this process. The maxillopalatine fenestrae are not well preserved. However, the anterior margin is bordered by the maxilla from a point level with the anterior end of M2, and the posterior margin is bordered by the palatine from a point level with the anterior end of M3. The suborbital shelf of the maxilla is flat, narrow and anteriorly tapered. The infraorbital canal is situated in the anterior portion of the suborbital shelf. The infraorbital foramen, positioned dorsal to the anterior end of M1, is elliptical in shape. The sphenopalatine foramen is positioned posterior to the infraorbital canal on the anterior end of the palatine. Both the sphenopalatine foramina are oval in shape. A subrounded maxillary foramen is located posterior to the maxillojugal suture. The sphenorbital fissure is large (approximately 6 mm wide). The foramen rotundum is located posterolateral to the sphenorbital fissure from which it is separated by a thin wall.
Lacrimal. Only the most lateral potion of the lacrimal is preserved. Two small lacrimal foramina occur on the anterior margin of the orbit.
Frontal, parietal, and interparietal. The dorsal anterior portion of the frontal is not preserved. In dorsal view, however, part of a deep sulcus is evident along the posterior portion of the metopic suture. An ethmoidal foramen is positioned at the posteroventral corner of the frontal along the frontal-orbitosphenoid suture. A well-developed sagittal crest is evident along the parietal-parietal suture. The parietals curve gently to form a well-developed nuchal crest. A wedge between the anterior wings of the parietals is formed by the frontals. The anterior wings of the parietals terminate dorsally where post-orbital constriction of the cranium occurs. A frontal-squamosal contact is evident posterior to postorbital constriction of the cranium. There is no contact between the alisphenoid and the parietals. No interparietal-parietal suture is present, suggesting that these bones have completely fused.
Zygomatic arch. The majority of the zygomatic arch is not preserved. The jugal extends anteriorly to the ventral portion of the lacrimal. There is a distinct, well-developed sulcus on the anterior extremity of the zygomatic arch. This sulcus appears to be related to the attachment of the superficial masseter muscle (Warburton, 2009). As in other balbarids, the zygomatic arch transitions smoothly into the facial region as opposed to being separated by a sulcus. The glenoid fossa is generally flat and merges smoothly into the ventral surface of the jugal. A prominent postglenoid process is present.
Neurocranium. The neurocranium is slightly domed. The frontal and parietals form most of the roof of the neurocranium. The ventral walls of the neurocranium are formed laterally by the dorsal wing of the squamosal. The ventral portion of the neurocranium is not preserved.
Basicranium. Small foramina are evident on the occipital condyle with short canals that open posteriorly into the foramen magnum. A hypoglossal foramen is situated medial to these foramina. The paroccipital and mastoid processes are partly broken. However, both appear to project below the level of the occipital condyle. The mastoid process appears more massive than the paroccipital process. A large mastoid foramen occurs on the mastoid-squamosal suture. The occipital condyles are small. The posterior lacerate foramen is only partially preserved but it appears to have been large.
The tympanic wing of the alisphenoid is flat. The external auditory meatus is bordered ventrally by the ectotympanic and dorsally by the squamosal. The ectotympanic has a straight posterior border, concave lateral border, and convex anterior and medial border. The ventral wall of the postglenoid process is contributed to by the ectotympanic. A distinct process is evident on the anteromedialmost corner of the ectotympanic. The zygomatic epitympanic sinus is large with a thin mesial wall. The basioccipital is not preserved.
Upper dentition. The upper dentition for Ganawamaya acris is described in Cooke (1992) except for the dP3, which is preserved in QM F19686. In occlusal view, the dP3 is trapezoidal in outline with a longer buccal margin compared to the lingual one. The paracone and metacone are subequal in height and taller than the protocone and metaconule. The protocone is large and taller than the metaconule. The paracone and protocone are not connected by a protoloph. A weak crest extends lingually from the paracone to meet the preparacrista. The postprotocrista extends posteriorly from the protocone to meet a short, very poorly developed premetaconule crista. A small stylar cusp C (StC) is present buccal to the paracone. A well-developed stylar cusp A (StA) is evident anterobuccal to the paracone. A poorly developed preparacrista extends from the paracone to the base of the StA. A well-defined postparacrista extends posteriorly into the interloph valley where it meets a poorly developed premetacrista. A postmetacrista extends posteriorly from the metacone but it is unclear where it terminates because part of the back of the tooth is obscured by a small piece of unprocessed limestone matrix.
Lower dentition. The lower dentition for Ganawamaya acris is described in Cooke (1992) except for p2 and dp3 which are preserved in QM F30870 and QM F19596.
The p2 is a short, tear-shaped tooth in occlusal view with steeply sloping buccal and lingual faces. Two prominent cuspids are evident on the tooth each with faint associated transcristids. The main crest departs in a posterior direction from the anteriormost cuspid posteriorly and terminates at the posterior end of the tooth. In buccal view the occlusal surface appears slightly convex.
The dp3 is triangular in occlusal outline and tapers anteriorly. Anteriorly, it abuts with the posterior end of p2. The protoconid is centrally positioned on the trigonid and is the tallest cusp on the tooth. A paracristid descends anteriorly from the protoconid to contact a well-developed paraconid. In QM F19596, a small cusp is present anterolingual to the protoconid and is connected to the paracristid by a short crest. A distinct protostylid is present buccal to the protoconid. The metaconid is well developed. The protoconid, paraconid, and metaconid are laterally compressed. A postmetacristid descends posteriorly into the interlophid valley where it meets a preentocristid. The cristid obliqua extends anterolingually from the hypoconid to the interlophid valley. The hypolophid is formed buccally by the posthypocristid and lingually by a buccal crest from the entoconid. The posthypocristid continues along the posterior flank of the hypolophid and meets the postentocristid at the posterolingual end of the tooth, encircling a small hypocingulid (a cingulid around the posterior base of the hypolophid). The postentocristid is well developed and continues vertically down the entoconid.
Additional morphological variation observed compared to the description by Cooke (1992) in the lower dentition includes the following: a protostylid is present on m 1 in all juvenile specimens that have unworn molars (e.g., QM F19899, 57790, 57789); complex enamel ridges on the i1 of some juvenile specimens such as QM F19899 and QM F16842 (the holotype of Gan. ornata); the paracristid is straight in worn specimens (e.g., holotype of Gan. acris QM F 16840 and 57790) but sinuous in juvenile and unworn specimens (e.g., QM F19899 and 57789); five cuspids are present on the occlusal surface of p3 on specimens such as QM F16842, 19899 and 57790, but in the holotype, QM F16840, the fifth cuspid appears to be obscured by wear. A malformation of the bone is evident on the anterior ventral border of the dentary of QM F57789, and was previously noted in an unpublished thesis by Cooke (1996).
Remarks. A remnant protostylid is evident in unworn juvenile specimens of Balbaroo (e.g., B. fangaroo and B. nalima) but is absent in worn adult specimens (Black et al., 2014). In the description of Gan. acris by Cooke (1992), Ganawamaya is distinguished from species of Nambaroo by the lack of a protostylid on m1. The holotype of Gan. acris is however significantly worn and has a distinct wear facet where the protostylid was most likely present. Juvenile specimens, such as those attributed to ‘ Nambaroo sp. 4 ’ by Cooke (1997a) and the holotype of Gan. ornata Cooke, 1992, and some unworn adult specimens (Figure 3), retain features such as complex enamel ridges on molars, a sinuous paracristid, and a protostylid on the m1. The holotype of Gan. ornata is missing m1, and therefore lacks sufficient diagnostic morphological features to separate it from Gan. acris. Other previously unpublished Ganawamaya specimens identified from Wayne’s Wok, the type locality for Gan. ornata, are also consistent with Gan. acris. The dp3 and p3 of QM F2003 from the type locality of Gan. acris (RSO Site) is also identical to the holotype of Gan. ornata and specimens of Gan. acris. We therefore propose that specimens attributed to undescribed Ganawamaya and Nambaroo species (Ganawamaya sp. 4, Nambaroo sp. 2, Nambaroo sp. 4, Nambaroo sp. 5 and Nambaroo sp. 6) from Faunal Zone B by Cooke (1997a), in addition to the holotype of Gan. ornata (QM F16842), be referred to Gan. acris. One specimen, QM F58649, is from Faunal Zone C, unlike the majority of Gan. acris specimens, which suggests that the species spanned the early to middle Miocene.
Age and distribution. The holotype of Gan. acris, QM F 16840, is from RSO Site, Riversleigh WHA, northwestern Queensland. The RSO Site is interpreted as to be part of Riversleigh’s Faunal Zone B (Archer et al., 1989, 1997; Travouillon et al., 2006, 2011; Arena et al., 2015) with radiometric dates by Woodhead et al. (2016) supporting an early Miocene age for RSO Site (16.55 ± 0.29 Ma). The RSO Site is interpreted by Arena et al. (2015) to belong to interval B3 within Faunal Zone B. Other referred specimens are from sites also considered to be part of interval B3 of Faunal Zone B: Camel Sputum Site, Inabeyance Site, Judith’s Horizontalis Site, Neville's Garden Site, Upper Site and Wayne's Wok Site (Arena et al., 2015). Several referred specimens from Boid Site and Creaser’s Ramparts Site, are interpreted as Faunal Zone B, intervals B2 or B3 (Arena et al., 2015). Radiometric dates reported by Woodhead et al. (2016) for Camel Sputum Site (17.75 ± 0.78 Ma) and Neville’s Garden Site (17.85 ± 0.13 Ma) support the interpretation that these are early Miocene in age. The Price Is Right Site has been interpreted to represent Faunal Zone B (Travouillon et al., 2006, 2011). Arena et al. (2015) found that its biostratigraphy was inconclusive, and it was as likely to be in either interval B2, B3, or C1. One specimen, QM F58649, is from Gag Site, which is interpreted to represent intervals C1 or C2 of Faunal Zone C, and thus middle Miocene in age (Archer et al., 1989, 1997; Travouillon et al., 2006, 2011; Arena et al., 2015). One specimen from the Wipajiri Formation, South Australia, is attributed to Gan. acris in our study. The Wipajiri Formation appears to be early or middle Miocene in age based on biocorrelation with Riversleigh deposits (Archer et al., 1997; Travouillon et al., 2006; Black et al., 2012).
description: Published as part of Butler, Kaylene, Travouillon, Kenny J., Price, Gilbert J., Archer, Michael & Hand, Suzanne J., 2018, Revision of Oligo-Miocene kangaroos, Ganawamaya and Nambaroo (Marsupialia: Macropodiformes, Balbaridae), pp. 1-58 in Palaeontologia Electronica (8 A) (8 A) 21 (1) on pages 4-13, DOI: 10.26879/747, http://zenodo.org/record/10961544