Ganguroo robustiter, sp. nov. (Macropodoidea, Marsupialia), a middle to early late Miocene basal macropodid from Riversleigh World Heritage Area, Australia

ABSTRACT——Cranial and dental remains of the middle to early late Miocene macropodid kangaroo, Ganguroo robustiter, sp. nov., are described. Postcranial remains of G. robustiter were previously described as referable to G. bilamina. Ganguroo robustiter is more robust (approximately 20% larger) and more derived than G. bilamina and G. bites, in having a larger m4, a well-developed posterolingual ridge and lingual cingulum on P3, a longer P3/p3, and no stylar cusp C on M3–M4. We used previously published data matrices to analyze the phylogenetic relationship of G. robustiter. Both phylogenetic analyses, using craniodental and postcranial characters, place G. robustiter within Macropodidae, as the sister taxon to sthenurines and macropodines. Species of Ganguroo are not found to be monophyletic despite their extreme similarity in character scores. This may be due to the large amount of missing data for G. bilamina and G. bites for which no postcranial remains have been identified. Phylogenetic results are ambiguous, recovering unresolved trees with low bootstrap values, but the generic assignment of these taxa is maintained because they are remarkably similar. Species of Ganguroo may represent a phyletic lineage, with species increasing in size and losing cusp/cuspids on their premolars through time, which appears to coincide with a broader record of changing vegetation and climates through the middle Miocene.http://zoobank.org/urn:lsid:zoobank.org:pub:D0B542BE-C673-4260-8381-8B163A35AC36SUPPLEMENTAL DATA——Supplemental materials are available for this article for free at www.tandfonline.com/UJVP

摘要——本文记述了中新世中晚期袋鼠科（Macropodidae）新种粗壮甘戈袋鼠（Ganguroo robustiter）的颅齿与颅后骨骼遗骸。此前曾有研究将粗壮甘戈袋鼠的颅后骨骼遗骸归属于双板甘戈袋鼠（G. bilamina）。相较于双板甘戈袋鼠与比氏甘戈袋鼠（G. bites），粗壮甘戈袋鼠体型更为粗壮（体型大约20%），演化程度更高，具体特征包括：下第四臼齿（m4）更大，上第三前臼齿（P3）具发育良好的后舌侧脊与舌侧齿带，上第三前臼齿/下第三前臼齿（P3/p3）更长，且上第三至第四臼齿（M3–M4）无C型尖柱（stylar cusp C）。本研究采用已发表的特征矩阵，对粗壮甘戈袋鼠的系统发育关系开展分析。基于颅齿特征与颅后骨骼特征的两项系统发育分析均显示，粗壮甘戈袋鼠隶属于袋鼠科，为短面袋鼠亚科（sthenurines）与袋鼠亚科（macropodines）的姊妹群。尽管甘戈袋鼠属（Ganguroo）各物种的特征分值极为相似，但该属并未形成单系群。这一现象可能源于双板甘戈袋鼠与比氏甘戈袋鼠存在大量缺失数据，且目前尚未发现二者的颅后骨骼遗骸。系统发育分析结果存在歧义，得到的未解析系统发育树自展支持率较低，但由于各分类群形态特征极为相似，仍保留其原有的属级归类。甘戈袋鼠属物种或代表一个直系演化谱系，随着时间推移，其体型逐渐增大，前臼齿的齿尖逐渐丢失，这一演化趋势似乎与中新世中期更广范围内的植被与气候变迁记录相吻合。http://zoobank.org/urn:lsid:zoobank.org:pub:D0B542BE-C673-4260-8381-8B163A35AC36补充数据——本文的补充材料可通过www.tandfonline.com/UJVP免费获取。