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We describe two new osteolaemine crocodylids from the Early and early Middle Miocene of Kenya: Kinyang mabokoensis tax. nov. (Maboko, 15 Ma) and Kinyang tchernovi tax. nov. (Karungu and Loperot, 18 Ma). Additional material referable to Kinyang is known from Chianda and Moruorot. The skull was broad and dorsoventrally deep, and the genus can be diagnosed based on the combined presence of a partial overbite, a subdivided fossa for the lateral collateral ligament on the surangular, and a maxilla with no more than 13 alveoli. Phylogenetic analyses based on morphological and combined morphological and molecular data support a referral of Kinyang to Osteolaeminae, and morphological data alone put the new taxon at the base of Euthecodontini. Some Kinyang maxillae preserve blind pits on the medial caviconchal recess wall. Kinyang co-occurs with the osteolaemine Brochuchus at some localities, and together, they reinforce the phylogenetic disparity between early Neogene osteolaemine-dominated faunas and faunas dominated by crocodylines beginning in the Late Miocene in the Kenya Rift. The causes of this turnover remain unclear, though changes in prevailing vegetation resulting from tectonic and climatic drivers may provide a partial explanation.

Brochuchusis a small crocodylid originally based on specimens from the early Miocene of Rusinga Island, Lake Victoria, Kenya. Here, we report occurrences ofBrochuchusfrom several early and middle Miocene sites. Some are from the Lake Victoria region, and others are in the Lake Turkana Basin. Specimens from the middle Miocene Maboko locality form the basis of a new species,Brochuchus parvidens, which has comparatively smaller maxillary alveoli. Because of the smaller alveoli, the teeth appear to be more widely spaced in the new species. We also provide a revised diagnosis forBrochuchusand its type species,B.pigotti. A phylogenetic analysis supports a close relationship betweenBrochuchusand tube-snoutedEuthecodon, but although relationships among crocodylids appear poorly resolved in the set of optimal trees, this is becauseBrochuchusandEuthecodon, along with early Miocene “Crocodylus”gariepensisfrom the early Miocene of Namibia, jointly adopt two distinct positions—either closely related to the living sharp-nosed crocodile (Mecistops) or to a group including the living dwarf crocodiles (Osteolaemus). Character support for a close relationship withMecistopsis problematic, and we suspect a closer relationship toOsteolaemuswill be recovered with improved sampling, but the results here are ambiguous. In either case,Brochuchusis more closely related to living groups not currently found in East Africa. This material helps constrain the timing of crocodylian faunal turnover in the East African Rift Valley System, with endemic lineages largely being replaced byCrocodylusin the middle or late Miocene possibly in response to regional xerification and the replacement of continuous rainforest cover with open grasslands and savannas.UUID:http://zoobank.org/e6f0b219-5f3e-44e5-bdb9-60a4fae8d126

The intra- and intermolecular deprotonation reactions of [(CpC5F4N)Fe(PEtNR′PEt)H]+ (PEtNR′PEt = (Et2PCH2)2NR′) complexes are rate-limiting processes in the electrocatalytic oxidation of hydrogen and can be mediated by an amine base in the outer coordination sphere (OCS) by facilitating the matching of energy of deprotonation intermediates. A series of complexes with different N-substituents (R′ = Me, Et, CH2OMe, CH2N(Ph)Me, and (CH2)nNMe2; n = 1–4) was examined computationally using density functional theory to determine the influence of the identity and proximity of the OCS base on the intramolecular deprotonation. Complexes with an OCS dimethylamino substituent were the most suitably energy matched. The number of carbon atoms between the secondary and OCS nitrogen atoms dictated the strength of the hydrogen-bonding interaction and ring strain following deprotonation of the iron hydride. The previously reported [(CpC5F4N)Fe(PEtNR′PEt)H]+ (R′ = (CH2)3NMe2) electrocatalyst was predicted to have the most f...