Nagoya City Science Museum

Distinctive anatomical features of bones can influence not only how these structures perform in living animals but also the tendency of elements to be transported by flowing water after death. Such transport can be critical in the concentration of fossils from animals that live near freshwater habitats, providing important context for interpreting the composition of paleocommunities. Measurements of the tendency of flowing water to disperse skeletal elements have been collected for diverse taxa, including mammals, turtles, and birds. However, these extant models may not be entirely appropriate for many morphologically distinct extinct lineages, such as non-avian dinosaurs. To expand the range of models available for evaluating the influence of hydrodynamic transport on the assembly of fossil deposits, we used a flow tank to measure the water speeds that disperse bones from a subadult American alligator (Alligator mississippiensis), with the skull and mandible tested in multiple starting orientations. Alligator bones are sorted into three main dispersal groups: early (vertebrae, most girdle elements), intermediate (ribs, most limb bones), and late (pubis, femur), with the skull and mandible varying between intermediate and late depending on orientation. Late dispersing elements tended to be heavy or very flat. These results can refine interpretations of the taphonomic context for deposits of fossil crocodylians and morphologically similar taxa (e.g., choristoderes, phytosaurs) and provide an additional comparative model for deposits of non-avian dinosaurs. Moreover, variation in hydrodynamic sorting across lineages highlights how distinctive anatomical features can influence the concentration of fossils, shaping understanding of assemblage composition and paleofaunal evolution.

Abstract Procoely in presacral and caudal vertebrae except the biconvex first caudal vertebra is regarded as a key diagnostic feature of eusuchian crocodylomorphs, although its individual variation, which may have an impact on the evolutionary and functional interpretations, remains unexplored. Here, we examined 19 extant species as well as a few fossil species of crocodylians to identify individual (intraspecific) variation in the intervertebral joint polarities. We found joint alteration in eight individuals from seven extant species and three individuals from two extinct species. Most variant specimens show sacrocaudal joint alteration, while single Osteolaemus tetraspis peculiarly displays multiple joint polarity reversions (cotyle to condyle and vice versa) in anterior caudal vertebrae. Because the sacrocaudal joint polarity is frequently reversed and the first caudal vertebra becomes procoelous, caution should be taken when identifying an isolated first caudal vertebra of basal and outgroups of eusuchians. Almost exclusive occurrences of joint alteration at the less mobile sacrocaudal joint in crocodylians are consistent with the hypothesis that the joint alteration takes place at joints with a lesser range of motion.

Abstract We report the first evidence for high-mass star formation triggered by collisions of molecular clouds in M 33. Using the Atacama Large Millimeter/submillimeter Array, we spatially resolved filamentary structures of giant molecular cloud 37 in M 33 using 12CO(J = 2–1), 13CO(J = 2–1), and C18O(J = 2–1) line emission at a spatial resolution of ∼2 pc. There are two individual molecular clouds with a systematic velocity difference of ∼6 km s−1. Three continuum sources representing up to ∼10 high-mass stars with spectral types of B0V–O7.5V are embedded within the densest parts of molecular clouds bright in the C18O(J = 2–1) line emission. The two molecular clouds show a complementary spatial distribution with a spatial displacement of ∼6.2 pc, and show a V-shaped structure in the position–velocity diagram. These observational features traced by CO and its isotopes are consistent with those in high-mass star-forming regions created by cloud–cloud collisions in the Galactic and Magellanic Cloud H ii regions. Our new finding in M 33 indicates that cloud–cloud collision is a promising process for triggering high-mass star formation in the Local Group.

Abstract In an attempt to carry out a systematic study on the behavior of the photospheric abundances of Li, C, and O (along with Fe) for Hyades main-sequence stars in the $ T_{\rm eff}$ range of $ \sim$ 5000–7000 K, we conducted an extensive spectrum-synthesis analysis applied to four spectral regions (comprising lines of Fe-group elements, Li I 6708 line, C I 7111–7119 lines, and O I 6156–8 lines), based on the high-dispersion spectra of 68 selected F–G type stars belonging to this cluster. The abundances of C and O turned out to be fairly uniform in a marginally supersolar level, such as like the case of Fe: $ \langle$ [C$ /$ H]$ \rangle$$ =$$ +$ 0.15 ($ \sigma$$ =$ 0.08), $ \langle$ [O$ /$ H]$ \rangle$$ =$$ +$ 0.22 ($ \sigma$$ =$ 0.14), and $ \langle$ [Fe$ /$ H]$ \rangle$$ =$$ +$ 0.11 ($ \sigma$$ =$ 0.08), suggesting that the primordial abundances are almost retained for these elements. Strictly, however, they show a slightly increasing trend with a decrease in $ T_{\rm eff}$ (typically on the order of $ \sim$ 10$ ^{-4}$ dex K$ ^{-1}$ ); while this might be due to an improper choice of atmospheric parameters, we found it difficult to give a quantitatively reasonable explanation. Regarding Li, we confirmed the well-known $ T_{\rm eff}$-dependent trend in the Li abundance reported so far (a conspicuous Li-trough at 6300 K $ ≲$$ T_{\rm eff}$$ ≲$ 6700 K and a progressive decrease toward a lower $ T_{\rm eff}$ at $ T_{\rm eff}$$ ≲$ 6000 K), which means that the surface Li of Hyades stars is essentially controlled only by $ T_{\rm eff}$ ; other parameters, such as the rotational velocity, are almost irrelevant.

Curators are always searching for the best educational method to exploit new technology in their educational activities. Our research group previously produced teaching materials using 3DCG animation in cooperation with the Nagoya City Science Museum. In this paper, we present a system research and development project that comprehensively supports various kinds of astronomy education by curators who can use information technology based on these activities. As a base system of this project, we built a content management system to support online teaching resources delivery in astronomy education for curators. In astronomy education, the most important thing is seeing real stars outdoors. Therefore curators want to support learning for beginners not only in science museums but also at homes and outdoors. Our system provides teaching materials that can be conducted outdoors and linked to planetarium programs. Curators used the system in practice and evaluated it to clarify its effectiveness.