 |
| Nimbacinus peterbridgei (top right) and Ngamalacinus nigelmarveni (bottom right) interacting with Kuterintja ngama (top left) and Gumardee springae (bottom left). Churchill, Archer & Hand, 2024 Illustration by Peter Schouten. |
ABSTRACT
New thylacinid species of Badjcinus, Nimbacinus, and Ngamalacinus are described from upper Oligocene deposits of the Riversleigh World Heritage Area, northwestern Queensland. Badjcinus timfaulkneri, Nimbacinus peterbridgei, and Ngamalacinus nigelmarveni are among the oldest thylacinids yet known and indicate an earlier diversification of the family than previously understood. Maximum parsimony analysis supports a sister group relationship between Ng. nigelmarveni and Ng. timmulvaneyi, but the relationships of the two other new taxa are unresolved. Bayesian dated total evidence analysis using morphological and molecular data supports the generic assignment of B. timfaulkneri and Ng. nigelmarveni but not that of Ni. peterbridgei. Both phylogenies herein support a taxonomic reassignment of Thylacinus macknessi to the genus Wabulacinus, a conclusion also supported by the results of previous studies. Body mass estimates based on molar size regressions indicate body sizes ranging from 3.7 kg to 11.4 kg for the new thylacinid species. Badjcinus timfaulkneri exhibits an extremely deep jaw compared with other thylacinids, with mandibular bending strength analysis suggesting that it was a highly durophagous carnivore much like the modern dasyurid Sarcophilus harrisii. This analysis also suggests Ni. peterbridgei had a dentary more similar in shape to that of plesiomorphic thylacinid faunivores such as Ni. dicksoni and T. cynocephalus suggesting that it had a relatively more generalist faunivorous diet. The molars of Ng. nigelmarveni suggest they were better suited for longitudinal slicing than the molars of B. timfaulkneri and Ni. peterbridgei, indicating a more hypercarnivorous diet compared with that of those species.
SYSTEMATIC PALEONTOLOGY
MAMMALIA Linnaeus, 1758
MARSUPIALIA Illiger, 1811 sensu Beck et al., 2014
DASYUROMORPHIA Gill, 1872 sensu Kealy & Beck 2017
THYLACINIDAE Bonaparte, 1838
BADJCINUS Muirhead & Wroe, 1998
BADJCINUS TIMFAULKNERI sp. nov.
Species Diagnosis—Badjcinus timfaulkneri differs from all other known thylacinids in possessing the following combination of lower dental features: large diastemas between both p1–p2 and p2–p3; broad talonids on all lower molars; m1 paraconid and paracristid highly reduced; m1 metaconid absent; m2–4 metaconids reduced; m4 larger than m3; three cusps on m4 talonid; two mental foramina below midpoints of m1 and m2. Badjcinus timfaulkneri differs from B. turnbulli in the following lower dental features: p1 less reduced in size relative to p2 and p3; larger diastemata between p1–p2 and p2–p3; anterior cingulid absent on m1; talonids broader on all molars.
Etymology—The species name timfaulkneri honors Tim Faulkner, head of conservation at the Australian Reptile Park and founder of The Devil Ark, for his life’s dedication to the conservation of dasyuromorphian marsupials and of Australian wildlife in general.
Holotype—QM F61721 (Fig. 1) is a near complete right dentary of an adult individual retaining p2 and m1–4, with alveoli for p1 and p3. Dental measurements are given in Table 1.
 |
| Nimbacinus peterbridgei (top right) and Ngamalacinus nigelmarveni (bottom right) interacting with Kuterintja ngama (top left) and Gumardee springae (bottom left). Illustration by Peter Schouten. |
NIMBACINUS Muirhead & Archer, 1989
NIMBACINUS PETERBRIDGEI sp. nov.
Species Diagnosis—Nimbacinus peterbridgei differs from the larger Ni. dicksoni in the following combination of lower dental features: the premolars and molars markedly less robust overall; the anterior cingulid on m2–4 extends beyond the buccal extremity of the trigonid; the cristid obliqua less transverse; the m4 trigonid angle is smaller; the m4 hypoconulid is large and is situated at the transverse midpoint of the talonid, rather than being lingually proximal to the entoconid; the hypoconid and entoconid are less reduced on m4.
Etymology—The species name peterbridgei honors mineralogist Peter Bridge OAM who has dedicated his life to bringing the past of Australia’s natural and cultural history into the present by supporting our paleontological field expeditions and publishing as well as authoring via Hesperian Press hundreds of books about Australia’s extraordinary human and natural history.
Holotype—QM F61723 (Fig. 3) is a right dentary preserving p1, p3, m2–4 and alveoli for p2 and m1. Dental measurements are shown in Table 2.
NGAMALACINUS Muirhead, 1997
NGAMALACINUS NIGELMARVENI Sp. Nov.
Species Diagnosis—Ngamalacinus nigelmarveni differs from Ng. timmulvaneyi in the following lower dental features; trigonids broader; trigonid angles smaller; entoconids and hypoconulids not closely twinned on m2–3; m3 entoconid smaller than that cusp in m2; metacristid longer on m2; m4 talonid broader; m4 posterior cristid longer and more transverse, with a distinct postmetacristid valley near the junction of the posthypocristid and prehypoconulecristid; m4 hypoconulid larger; m4 posterior cingulid longer and contacts the base of the postmetacristid valley.
Etymology—The species name nigelmarveni honors British television presenter and naturalist Nigel Marven for his lifetime dedication to inspiring young paleontologists through his unique and daring style of presenting documentaries on ancient life.
Timothy J. Churchill, Michael Archer and Suzanne J. Hand. 2024. Three New thylacinids (Marsupialia, Thylacinidae) from late Oligocene Deposits of the Riversleigh World Heritage Area, northwestern Queensland. Journal of Vertebrate Paleontology. e2384595. DOI: doi.org/10.1080/02724634.2024.2384595
