Erratum: Musineon glaucescens (Apiaceae), a new species from central Montana, U.S.A.

AbstractThe Careless Creek Quarry (CCQ) is a multitaxic bonebed in the Campanian Judith River Formation of south-central Montana (USA) that produced a diverse assemblage of vertebrates, including several dinosaurian clades. We describe the morphology of the CCQ hadrosaurid material and reevaluate its taxonomic affinities. Our osteological comparative observations, coupled with maximum parsimony phylogenetic analyses, indicate that the majority of the hadrosaurid material is referable to kritosaurin saurolophines. Only an ischium is unambiguously referable to Lambeosaurinae. Most of the kritosaurin specimens likely represent a taxon that forms a polytomy with species of Gryposaurus and Rhinorex condrupus Gates and Sheetz, 2015. This form may represent individuals of either G. latidens Horner, 1992 or G. notabilis Lambe, 1914, or a new species cogeneric or not with Gryposaurus. The juvenile material exemplifies several patterns of mandibular and appendicular osteological variation previously observed in other hadrosaurids. However, it also shows some departures from the common trends, supporting the fact that not all skeletal growth changes can be generalized to all hadrosaurids.

Purgatorius titusi, represented by 51 teeth and jaw fragments, is described from the lower Paleocene Bear Formation of the Crazy Mountains Basin in south-central Montana. Several synapomorphies, including a weak postprotocingulum and mesial inflection of molar trigonids, are indicative of the taxon's “plesiadapiform” affinities. Other features, such as wider stylar shelf and a less squared lingual outline on upper molars, are more primitive than those of Purgatorius unio, heretofore the earliest occurring species of well-represented primatomorphs.

Musineon glaucesens is described as a new species from two populations in the Big Belt Mountains of Montana, U.S.A. It appears to be most closely allied to the small genus Musineon which is endemic to western North America. It occurs just outside the range of M. vaginatum but differs from that species by its larger fruits, more widely lobed and glaucous leaves, and talus-slope habitat. 

The palaeostomatopod crustacean Bairdops beargulchensis Schram & Horner, 1978 (Malacostraca, Hoplocarida) from the Mississippian Bear Gulch Limestone is now seen as a taxonomic composite that arose from the confusion of specimens of two distinct hoplocarid species. These species are herein described as the palaeostomatopod Bairdops beargulchensis Schram & Horner, 1978 and a new species of archaeostomatopod, Tyrannophontes acanthocercus. Tyrannophontes acanthocercus is quite distinct from the Pennsylvanian archaeostomatopod T. Theridion from the Essex fauna (Mazon Creek), with which it was originally compared. Bairdops beargulchensis is very similar to the Mississippian palaeostomatopod, B. elegans, from the Scottish Glencartholm fauna. A previously proposed synonymy of B. beargulchensis with T. theridion is therefore rejected. A preliminary restudy of the archaeostomatopods T. Theridion and Gorgonophontes peleron, and the palaeostomatopods Perimecturus Rapax and P. parki, reveals some newly recognized characters of those taxa and suggests some novel interpretations of hoplocarid evolution. A cladistic phylogenetic analysis of the Hoplocarida including the Paleozoic forms resolves the higher level relationships of the hoplocarids (palaeostomatopods, archaeostomatopods, aeschronectids, and unipeltatans).