Giant dwarf crocodiles from the Miocene of Kenya and crocodylid faunal dynamics in the late Cenozoic of East Africa.

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.

Footprint evidence of early hominin locomotor diversity at Laetoli, Tanzania.

Bipedal trackways discovered in 1978 at Laetoli site G, Tanzania and dated to 3.66 million years ago are widely accepted as the oldest unequivocal evidence of obligate bipedalism in the human lineage1-3. Another trackway discovered two years earlier at nearby site A was partially excavated and attributed to a hominin, but curious affinities with bears (ursids) marginalized its importance to the paleoanthropological community, and the location of these footprints fell into obscurity3-5. In 2019, we located, excavated and cleaned the site A trackway, producing a digital archive using 3D photogrammetry and laser scanning. Here we compare the footprints at this site with those of American black bears, chimpanzees and humans, and we show that they resemble those of hominins more than ursids. In fact, the narrow step width corroborates the original interpretation of a small, cross-stepping bipedal hominin. However, the inferred foot proportions, gait parameters and 3D morphologies of footprints at site A are readily distinguished from those at site G, indicating that a minimum of two hominin taxa with different feet and gaits coexisted at Laetoli.

Snapshots of human anatomy, locomotion, and behavior from Late Pleistocene footprints at Engare Sero, Tanzania.

Fossil hominin footprints preserve data on a remarkably short time scale compared to most other fossil evidence, offering snapshots of organisms in their immediate ecological and behavioral contexts. Here, we report on our excavations and analyses of more than 400 Late Pleistocene human footprints from Engare Sero, Tanzania. The site represents the largest assemblage of footprints currently known from the human fossil record in Africa. Speed estimates show that the trackways reflect both walking and running behaviors. Estimates of group composition suggest that these footprints were made by a mixed-sex and mixed-age group, but one that consisted of mostly adult females. One group of similarly-oriented trackways was attributed to 14 adult females who walked together at the same pace, with only two adult males and one juvenile accompanying them. In the context of modern ethnographic data, we suggest that these trackways may capture a unique snapshot of cooperative and sexually divided foraging behavior in Late Pleistocene humans.

Holocene footprints in Namibia: the influence of substrate on footprint variability.

We report a Holocene human and animal footprint site from the Namib Sand Sea, south of Walvis Bay, Namibia. Using these data, we explore intratrail footprint variability associated with small variations in substrate properties using a "whole foot" analytical technique developed for the studies in human ichnology. We demonstrate high levels of intratrail variability as a result of variations in grain size, depositional moisture content, and the degree of sediment disturbance, all of which determine the bearing capacity of the substrate. The two principal trails were examined, which had consistent stride and step lengths, and as such variations in print typology were primarily controlled by substrate rather than locomotor mechanics. Footprint typology varies with bearing capacity such that firm substrates show limited impressions associated with areas of peak plantar pressure, whereas softer substrates are associated with deep prints with narrow heels and reduced medial longitudinal arches. Substrates of medium bearing capacity give displacement rims and proximal movement of sediment, which obscures the true form of the medial longitudinal arch. A simple conceptual model is offered which summarizes these conclusions and is presented as a basis for further investigation into the control of substrate on footprint typology. The method, model, and results presented here are essential in the interpretation of any sites of greater paleoanthropological significance, such as recently reported from Ileret (1.5 Ma, Kenya; Bennett et al.: Science 323 (2009) 1197-1201).

Peripheral blood levels of matrix metalloproteinases in patients referred for percutaneous balloon mitral valve commissurotomy.

BACKGROUND AND AIM OF THE STUDY: Inflammation may play a central role in the progression of stenotic valvular heart disease. Serum levels of matrix metalloproteinases (MMPs), markers of extracellular matrix (ECM) turnover and potential markers of active inflammation, have been recently demonstrated in several inflammatory processes. The present study was designed to examine whether systemic evidence of ECM turnover was present in advanced stenotic mitral valve disease. METHODS: Serum levels of MMP-1, -3 and -9 were measured in 114 patients with mitral stenosis referred for percutaneous balloon mitral valve commissurotomy, and compared to those in 48 healthy, age- and gender-matched controls. RESULTS: Serum levels of MMP-1, -3 and -9 did not vary according to hemodynamic profile or heart failure class at the time of blood sampling. Levels of MMP-1 and -3 were not significantly different between those patients with mitral stenosis and controls. The level of MMP-9 was significantly higher in patients with mitral stenosis than in controls, and did not appear to be altered by commissurotomy. CONCLUSION: Serum levels of MMP-9 were elevated in patients with mitral stenosis, providing further evidence that inflammation and ECM remodeling plays an important role in the pathophysiology of valvular heart disease.

Usefulness of percutaneous balloon mitral commissurotomy in preventing the development of atrial fibrillation in patients with mitral stenosis.

A prospective cohort of patients with mitral stenosis and no history of atrial arrhythmias showed no decrease in the incidence of atrial fibrillation (AF) after successful versus unsuccessful Inoue balloon percutaneous balloon mitral valve commissurotomy. Advanced age and left atrial dimension best predicted which patients developed AF during follow-up, whereas percutaneous balloon mitral valve commissurotomy procedural success and left atrial pressure reduction did not have an impact on incidence of AF.

C-reactive protein elevation independently influences the procedural success of percutaneous balloon mitral valve commissurotomy.

BACKGROUND: Markers of systemic inflammation including C-reactive protein (CRP) appear to predict morbidity and mortality in various clinical conditions. The presence of systemic inflammation and its impact on the procedural success of percutaneous balloon mitral valve commissurotomy (PBMC) in patients with rheumatic mitral stenosis has not been previously demonstrated. METHODS: Measurements of CRP with a high-sensitivity assay were performed at the time of PBMC or during post-procedural follow-up in 119 patients with mitral stenosis of rheumatic morphology. Patients were questioned to exclude confounders of CRP elevation and categorized into undetectable (< or =0.10 mg/L) and detectable (>0.10 mg/L) CRP levels. Detectable levels were further classified into assay range (>0.10 and < or =6.0 mg/L) and elevated (>6.0 mg/L). RESULTS: CRP was detectable in 76% of patients and elevated (>6.0 mg/L) in 36% of patients studied. Procedural success occurred in 89% of patients with undetectable CRP, as compared with only 67% in patients with detectable CRP (P =.028). This effect remained after controlling for age and valve score (previously described predictors of PBMC success). CONCLUSIONS: Systemic inflammation is common in patients with rheumatic mitral valve stenosis, and the relationship between procedural success and CRP suggests persistent inflammation may affect the results of PBMC.