Mesozoic

Crommium angustatum Grateloup, 1827 fossil snail shell (apical view) from the Oligocene of France. (42 mm across at its widest) Of all the molluscs, the gastropods (snails) have made the most ecological adaptations. They can be found in almost all fundamental environments: marine, freshwater, terrestrial. Most gastropods live in the ocean, and have a single, asymmetrically coiled, external shell of calcium carbonate (CaCO3 - usually aragonite). The hard calcareous shell is the most easily fossilized part of the gastropod. The soft parts of a snail (the “slug” portion) include a well developed head having eyes, tentacles, and a mouth, and a well developed, strong, muscular foot used principally for locomotion. The shell is carried upright on the snail’s back, or is partially dragged behind. When threatened by a predator, many snails can retract their soft parts into the shell’s interior for protection. Many fossil snails in the Paleozoic rock record are often not well preserved, or are preserved as internal molds. The original aragonite of many gastropod shells is not stable on geologic time scales, and often recrystallizes or dissolves completely away. Fossil snail shells in Mesozoic and Cenozoic rocks are usually better preserved. Classification: Animalia, Mollusca, Gastropoda, Naticoidea, Ampullinidae Age: Rupelian Stage (Stampian Stage), Lower Oligocene Locality: Gaas, Landes Department, Aquitaine, southwestern France

Crommium angustatum Grateloup, 1827 fossil snail shell (apical view) from the Oligocene of France. (42 mm across at its widest) Of all the molluscs, the gastropods (snails) have made the most ecological adaptations. They can be found in almost all fundamental environments: marine, freshwater, terrestrial. Most gastropods live in the ocean, and have a single, asymmetrically coiled, external shell of calcium carbonate (CaCO3 - usually aragonite). The hard calcareous shell is the most easily fossilized part of the gastropod. The soft parts of a snail (the “slug” portion) include a well developed head having eyes, tentacles, and a mouth, and a well developed, strong, muscular foot used principally for locomotion. The shell is carried upright on the snail’s back, or is partially dragged behind. When threatened by a predator, many snails can retract their soft parts into the shell’s interior for protection. Many fossil snails in the Paleozoic rock record are often not well preserved, or are preserved as internal molds. The original aragonite of many gastropod shells is not stable on geologic time scales, and often recrystallizes or dissolves completely away. Fossil snail shells in Mesozoic and Cenozoic rocks are usually better preserved. Classification: Animalia, Mollusca, Gastropoda, Naticoidea, Ampullinidae Age: Rupelian Stage (Stampian Stage), Lower Oligocene Locality: Gaas, Landes Department, Aquitaine, southwestern France

Crommium angustatum Grateloup, 1827 fossil snail shell (abapertural view) from the Oligocene of France. (57 mm tall) Of all the molluscs, the gastropods (snails) have made the most ecological adaptations. They can be found in almost all fundamental environments: marine, freshwater, terrestrial. Most gastropods live in the ocean, and have a single, asymmetrically coiled, external shell of calcium carbonate (CaCO3 - usually aragonite). The hard calcareous shell is the most easily fossilized part of the gastropod. The soft parts of a snail (the “slug” portion) include a well developed head having eyes, tentacles, and a mouth, and a well developed, strong, muscular foot used principally for locomotion. The shell is carried upright on the snail’s back, or is partially dragged behind. When threatened by a predator, many snails can retract their soft parts into the shell’s interior for protection. Many fossil snails in the Paleozoic rock record are often not well preserved, or are preserved as internal molds. The original aragonite of many gastropod shells is not stable on geologic time scales, and often recrystallizes or dissolves completely away. Fossil snail shells in Mesozoic and Cenozoic rocks are usually better preserved. Classification: Animalia, Mollusca, Gastropoda, Naticoidea, Ampullinidae Age: Rupelian Stage (Stampian Stage), Lower Oligocene Locality: Gaas, Landes Department, Aquitaine, southwestern France

Permineralized Jurassic fern rhizome from Korsaröd (Sweden) of Osmundastrum pulchellum. It has preserved Nuclei and Chromosomes, a fine subcellular detail has rarely been documented in fossils. It´s Rooted in DNA content was used to extrapolate relative genome, finding relationships with extant Osmundastrum cinnamomeum, and confirmed a monophyletic Osmunda. Osmundastrum pulchellum is one of the earliest fossil Osmundastrum rhizomes known so far, and the first of its kind from the Mesozoic of Europe. Its impressive preservation has lead to know even the biotic interactions with the Plant. It also has recovered the only know case know to preserve the ongoing mitosis processes in plant cells via calcification from volcanic hydrothermal brine.

New species of Mesozoic benthic foraminifera from the former British Petroleum micropalaeontology collection, Ophthalmidium dracomaris n. sp. (1) holotype (NHMUK PM PF 74496); (2–5) paratypes (NHMUK PM PF 74497–74500). (8–9) Eobigenerina calloviensis n. sp.: (8) holotype (NHMUK PM PF 74504); (9) paratype (NHMUK PM PF 74505). (10–12) Trochammina fordonensis n. sp.: (10) holotype (NHMUK PM PF 74501); (11–12) paratype (NHMUK PM PF 74502–74503). (13–15) Arenoturrispirillina swiecickii n. sp.: (13) holotype (NHMUK PM PF 74506); (14–15) paratype (NHMUK PM PF 74507 + NHMUK PM PF 74552). (16–17) Ataxophragmium mariae n. sp.: (16) holotype (NHMUK PM PF 74553); (17) paratype (NHMUK PM PF 74554).

HKU zh:香港大學 Stephen Hui Geological Museum zh:許士芬地質博物館 Mesozoic 中生代 rocks Oct 2016

Graph of relative Dinosaur fossil populations from each period of geologic time in the Mesozoic, ordered by major clade

"Life in the Mesozoic" exhibit, Burke Museum, University of Washington, Seattle, Washington.

Quarry called “Ratssteinbruch” at Plauenscher Grund (gorge-like valley of the river Weißeritz nearby/in the city of Dresden, Saxony, Germany), Upper Carboniferous Monzonite (historically identified as Syenite) of the Meißen Massif (Paleozoic basement) unconformably overlain by Upper Cenomanian beds of the Dölzschen Formation, yellowish basal conglomerate and overlying bluish silty clay-marlstone (“plenus-Pläner”) of the Saxo-Bohemian Cretaceous Basin (Mesozoic platform).[1]

Figure 1. Evolution of macroecological traits in Dinosauria. Large scale event in dinosaur evolution (a); the origin of dinosaurs (star), hyperthermals (volcano), the earliest fossil Avialae (bird), the earliest fossil angiosperm (flower), the Cretaceous/Palaeogene mass extinction (asteroid). Phylogeny of dinosaurs (b) redrawn from Sereno and adapted to the current consensus and upon which an ancestral state reconstruction of temperature niche (mean annual temperature) after Chiarenza et al. is plotted; Mesozoic palaeogeographies (c) for Triassic (T), Jurassic (J) and Cretaceous (K). Silhouette colours symbolize body mass for each of the taxa represented; information on dietary habits are plotted after Barrett and Zanno & Makovicky; numbers represent clades discussed through this study: 1, Ornithischia; 2, Thyreophora; 3, Ornithopoda; 4, Hadrosauroidea; 5, Marginocephalia; 6, Ceratopsia; 7, Saurischia; 8, Sauropodomorpha; 9, Sauropoda; 10, Theropoda; 11, Ceratosauria; 12, Tetanurae; 13, Coelurosauria; 14, Maniraptoriformes; 15, Maniraptora; 16, Deinonychosauria; 17, Avialae; 18, Ornithothoraces. Palaeogeographies modified from original plots via R package ‘mapast’ using plate models by Scotese.

Life restoration of the Triassic ichthyosaur Qianichthyosaurus xingyiensis. References Motani, Ryosuke; Jiang, Da-yong; Tintori, Andrea; Ji, Cheng; Huang, Jian-dong (2017). "Pre- versus post-mass extinction divergence of Mesozoic marine reptiles dictated by time-scale dependence of evolutionary rates". Proceedings of the Royal Society B 284 (1854): 20170241. DOI:10.1098/rspb.2017.0241.

Australian Mesozoic pterosaurs. A, Aussiedraco molnari (QM F10613; holotype) mandible in dorsal view. Scale = 1 cm. B, Mythunga camara (QM F18896; holotype) partial skull and mandible in left lateral view. Scale = 5 cm. C, Thapunngaka shawi (KK F494; holotype) mandible in left lateral view. Scale = 5 cm. D, Ferrodraco lentoni (AODF 0876; holotype [part]) partial skull and mandible in left lateral view. Scale = 5 cm.

Sibişel River (Strei) near the Sânpetru Mesozoic Formation, Romania