Changes in shell durability of common marine taxa through the Phanerozoic: evidence for biological rather than taphonomic drivers.

Abstract.-Phanerozoic trends in shell and life habit traits linked to postmortem durability were evaluated for the most common fossil brachiopod, gastropod, and bivalve genera in order to test for changes in taphonomic bias. Using the Paleobiology Database, we tabulated occurrence frequencies of genera for 48 intervals of ,11 Myr duration. The most frequently occurring genera, cumulatively representing 40% of occurrences in each time bin, were scored for intrinsic durability on the basis of shell size, reinforcement (ribs, folds, and spines), life habit, and mineralogy. Shell durability is positively correlated with the number of genera in a time bin, but durability traits exhibit different temporal patterns across higher taxa, with notable offsets in the timing of changes in these traits. We find no evidence for temporal decreases in durability that would indicate taphonomic bias at the Phanerozoic scale among commonly occurring genera. Also, all three groups show a remarkable stability in mean shell size through the Phanerozoic, an unlikely pattern if strong sizefiltering taphonomic megabiases were affecting the fossil record of shelly faunas. Moreover, small shell sizes are attained in the early Paleozoic in brachiopods and in the latest Paleozoic in gastropods but are steady in bivalves; unreinforced shells are common to all groups across the entire Phanerozoic; organophosphatic and aragonitic shells dominate only the oldest and youngest time bins; and microstructures having high organic content are most common in the oldest time bins. In most cases, the timing of changes in durability-related traits is inconsistent with a late Mesozoic Marine Revolution. The post-Paleozoic increase in mean gastropod reinforcement occurs in the early Triassic, suggesting either an earlier appearance and expansion of durophagous predators or other drivers. Increases in shell durability hypothesized to be the result of increased predation in the late Mesozoic are not evident in the common genera examined here. Infaunal life habit does increase in the late Mesozoic, but it does not become more common than levels already attained during the Paleozoic, and only among bivalves does the elevated late Mesozoic level persist through the Holocene. These temporal patterns suggest control on the occurrence of durability-related traits by individual evolutionary histories rather than taphonomic megabiases. Our findings do not mean taphonomic biases are absent from the fossil record, but rather that their effects apparently have had little net effect on the relative occurrence of shell traits generally thought to confer higher preservation potential over long time scales

Comparison of chosen physical fitness characteristics of Turkish professional basketball players by division and playing position.

The purpose of the present study was to compare chosen physical fitness characteristics of Turkish professional basketball players in different divisions (first and second division) and playing positions. Forty-five professional male basketball players (14 guards, 15 forwards, 16 centers) participated in this study voluntarily. For each player, anthropometric measurements were performed, as well as a multi-stage 20 m shuttle run, isokinetic leg strength, squat jump (SJ), countermovement jump (CMJ), 10-30 meter single-sprint and T-drill agility tests. The differences in terms of division were evaluated by independent t-test and the differences by playing position were evaluated by one-way ANOVA with Post Hoc Tukey test. First division players' CMJ measurements were significantly higher than those of second division players' (p≤0.05), whereas second division players' 10 m sprint times were significantly better than those of first division players' (p≤0.05). In addition, forwards and centers were significantly taller than guards. Centers were significantly heavier and their T-drill test performances were inferior to those of forwards and guards (p≤0.05). Moreover, guards had a significantly higher maximal oxygen uptake (VO2 max) than centers. Guards and forwards showed significantly better performance in the 10 and 30 m sprint tests than centers (p≤0.05). Forwards and centers had significantly better left leg flexor strength at 180°.s(-1)(p≤0.05). In conclusion, the findings of the present study indicated that physical performance of professional basketball players differed among guards, forwards and centers, whereas there were not significant differences between first and second division players. According to the present study, court positions have different demands and physical attributes which are specific to each playing position in professional basketball players. Therefore, these results suggest that coaches should tailor fitness programs according to specific positions on the court

A comparison of heart rate response and frequencies of technical actions between half-court and full-court 3-a-side games in high school female basketball players.

The purpose of this study was to compare heart rate (HR) response and frequency of technical actions between half-court and full-court 3-a-side games in female high school basketball players. Twelve young female basketball players (age 15.5 ± 0.5 years; height 165.1 ± 5.7 cm; body mass 57.3 ± 7.2 kg; training age 4.2 ± 0.7 years; HRmax 202.9 ± 5.6 b·min(-1)) participated in this study voluntarily. On the first day, anthropometric measurements (height and body mass) were taken for each player; this was followed by the Yo-Yo intermittent recovery test (YIRT) level 1 for the subjects. Then, half-court and full-court 3-a-side games were organized in random order at 2-day intervals. The HRmax for each player was determined during the YIRT, after which the HR was measured during the 3-a-side games. In addition, the frequencies of different categories of technical actions were counted manually during the 3-a-side games. A paired t-test was calculated for each dependent variable, including HR, percentage of maximum HR (%HRmax), and the frequencies of different technical actions to compare half-court and full-court 3-a-side games. The study results indicate that the full-court 3-a-side games produced significantly higher responses than the half-court 3-a-side games in terms of HR and %HRmax (p < 0.05), whereas the half-court games resulted in significantly higher frequencies of technical actions (p < 0.05). The results of this study suggest that, if coaches want to achieve greater HR responses, coaches of female high school basketball players should organize full-court 3-a-side games, whereas coaches who want to focus on technical actions should arrange half-court 3-a-side games

Ultrasonographic assessment of the quadriceps muscle and femoral cartilage in transtibial amputees using different prostheses.

BACKGROUND: In patients with lower limb amputations, gait alteration, increased loading on the intact extremity, and use of prosthesis may lead to joint degeneration. OBJECTIVE: To explore the effects of prosthesis type on quadriceps muscle and distal femoral cartilage thicknesses in transtibial amputees. STUDY DESIGN: A cross-sectional study. METHODS: A total of 38 below-knee amputees were enrolled in the study, of which 13 patients were using vacuum system type prosthesis and 25 patients were using silicon liner pin system prosthesis. Patients' femoral cartilage and quadriceps muscle thickness measurements were performed using musculoskeletal ultrasound. RESULTS: When compared with the intact sides, cartilage and rectus femoris, vastus intermedius, and vastus medialis muscle thickness values were significantly decreased on the amputee sides (all p < 0.05). Clinical characteristics and ultrasound measurements were similar between the two groups except the lateral and medial femoral condyle thicknesses, thinner in the silicon liner pin system users (both p < 0.05). CONCLUSION: The distal femoral cartilage and quadriceps muscle thicknesses were found to be decreased on the amputated sides, and the negative impact on the cartilage seemed to be worse in the silicon liner pin system users. CLINICAL RELEVANCE: This study might provide another argument as regards the preference of vacuum system type prosthesis to prevent possible knee osteoarthritis due to cartilage thinning in adult transtibial amputees