Macropodoids from the Tarkarooloo local fauna, including Nambaroo tarrinyeri n. gen. and sp., N. saltavus n. sp., N. novus n. sp. and Palaeopotorous priscus n. gen. and sp., include the most plesiomorphic macropodids and potoroids known. Together with the newly discovered macropodoids from the Pinpa and Yanda local faunas they are also the oldest macropodoids described. Study of the morphology of these plesiomorphic macropodoids indicates that the trigonid of the M2 in potoroids and macropodids is composed of different structures (the protoconid and metaconid in macropodids and the protoconid and protostylid in potoroids). Also, the posterior cingulum in macropodids is a neomorphic structure, and not homologous with the posterior cingulum (the posthypocristid and postentocristid) in potoroids and phalangerids. A unique M2 trigonid configuration, where the cristid obliqua connects with the protostylid, is here recognized as being present in plesiomorphic macropodoids and phalangerids, and possibly represents a synapomorphy for a clade containing members of those groups.

Mineral separates of five tuffs interbedded in the mammal-bearing Huayquerías and Tunuyán formations in Mendoza Province, west-central Argentina, were dated by the 40K-40Ar method. At the locality of Rio Seco Ultima Aguada on the east side the Meseta Guadal three biotite concentrates of a tuff from a level that apparently corresponds to the very top of the Huayquerias Formation (or less probably to the very bottom of the Tunuyan Formation, sensu Dessanti, 1946) yielded an average age of 5.8 ± 0.1 Ma. The boundary between the Huayquerias Formation (namesake and type formation and fauna of the Huayquerian Land Mammal Age) and the Tunuyan Formation (which contains a Montehermosan age fauna at this locality) is thus about 5.8 Ma. At the locality of Rio Seco de la Salada on the west side of the Meseta Guadal, glass concentrates from two tuffs in the upper part of the Tunuyan Formation yielded ages of 2.6 ± 0.1 and 2.4 ± 0.3 Ma, respectively (the latter date is from a tuff located 90 m stratigraphically above the former). These dates indicate that the rocks and faunas from the upper part of the Tunuyan Formation are of Chapadmalalan (i.e., 2.8 to 2.5 Ma) and Uquian (i.e., 2.5 to 1.5 Ma) age. The faunas from the lower and middle parts of the Tunuyan Formation on the east side of the Meseta Guadal are apparently all of Montehermosan age (i.e., ca. 6.0 to 2.8 Ma).

A new oromerycid, Montanatylopus matthewi n. gen., n. sp., is described from the early medial Chadronian (early Oligocene, about 36 Ma) of McCarty's Mountain, Madison County, Montana. It is much larger and has higher crowned teeth than other known oromerycids. Montanatylopus is most closely related to Eotylopus from the Chadronian of the High Plains and Trans-Pecos Texas.

Isolated cheek teeth of the hypsodont one-toed horses Astrohippus stocki and Dinohippus mexicanus are described from ten localities within the classic vertebrate-bearing beds of the Bone Valley phosphate mining district and one new locality (containing the Lockwood Meadows Local Fauna) in Sarasota, Florida. All occurrences of these taxa are from the upper Bone Valley Formation and further confirm a late Hemphillian (late Miocene to early Pliocene) age, or within the range of about 5.4 to 4.5 myBP for this part of the sedimentary sequence. In contrast to the common occurrences of hipparions in the Bone Valley Formation, A. stocki and D. mexicanus are relatively rare. In some dental charcters such as protocone length and crown height, A. stocki and D. mexicanus are no more advanced in their stage of evolution than the advanced three-toed horses Neohipparion eurystyle, N. gidleyi and Nannippus peninsulatus.

Mid-Carboniferous (upper Chesterian–lower Atokan) rocks exposed north of the Snake River Plain in east-central Idaho are assigned to the Arco Hills, Bluebird Mountain and lower Snaky Canyon formations (ascending order). In the southern Lemhi Range, calcareous algae and associated microproblematica from these rocks include representatives of at least 13 genera and genus-level taxa within the Dasycladaceae, Aoujgaliaceae, Ungdarellaceae, and incertae familiae. Local appearances of Masloviporidium delicata and Donezella lutugini are early Morrowan or younger as determined independently by studies of associated foraminifers and conodonts. Beresella polyramosa and Komia abundans are locally restricted to Atokan rocks. These findings are consistent with compiled data on worldwide stratigraphic distributions of these taxa, and suggest that certain Upper Paleozoic calcareous algae may be of limited value in biostratigraphic correlation.

In downtown Richmond, Va., a highly diatomaceous deposit contains a diatom assemblage in which 87 taxa have been identified. The diatoms indicate that this sedimentary unit is correlative with Lithologic Unit 19 of the Choptank Formation of middle Miocene age. Also in Richmond, a sedimentary unit correlated with the Eastover Formation overlies the Choptank Formation and contains a sparse diatom assemblage in which 24 taxa have been identified. The diatoms in this upper deposit form an assemblage that is distinctive from that of the Choptank Formation and is of late Miocene age. Both diatom assemblages are dominated by taxa indicating deposition in a littoral or shallow neritic marine environment. Although reasons for differences in diatom diversity and abundance between the two formations are obscure, these differences appear to reflect the greater primary productivity of diatoms in middle Miocene than in later Tertiary time.

Globorotalia danvillensis was described by Howe and Wallace (1932) from beds at Danville Landing on the Ouachita River, Louisiana. Fisk (1938) gave these beds formational status, because he considered them to be a mappable unit, representing the uppermost Eocene deposits in Louisiana. These beds are placed in the Globorotalia cerroazulensis s.l. Zone. Globorotalia danvillensis was later reported by Bergquist (in Bergquist and McCutcheon, 1942) from upper Eocene beds in Mississippi. The present authors have found the same species in beds of the Lower Jackson Group at Montgomery Landing, Louisiana, which include the upper part of the Porticulasphaera semiinvoluta Zone and the lower part of the Globorotalia cerroazulensis Zone. During the investigation it was found that the species exhibits small, secondary, sutural apertures on the spiral side, which places it in the genus Truncorotaloides Brönnimann and Bermúdez (1953). Howe (1939), in his study of the Cook Mountain foraminifera, followed the custom of that time (see Cushman and Dusenbury, 1934, p. 63) of tentatively referring small coiled species of planktonic foraminifera to Globigerina cretacea d'Orbigny. Re-examination of samples from the Cook Mountain Formation of Saline Bayou, Winn Parish, Louisiana (H. V. Howe collection M 524–527) reveals that many of Howe's specimens belong to Truncorotaloides danvillensis. This species occurs here together with T. rohri Brönnimann and Bermúdez.

In an effort to update taxonomic, locality, and morphological data for type specimens in the Museum of Geology, a number of catalogue and published errors were discovered. This contribution is intended to inform researchers of the errors and to remedy those problems that can now be solved. Original omissions of collection data have been updated as much as possible without introducing unsubstantiated conclusions. The discrepancies are reviewed as numerical and locality changes and are arranged taxonomically.