Description: The trilobites, belonging to the arthropod phylum and trilobita, only lived in the Paleozoic ocean, appeared in the Cambrian of the Early Paleozoic, and were completely extinct in the geological disaster event at the end of the Permian. The shell of the trilobite body is divided into a central axis and two lateral leaves, so it is called trilobite, and is divided into three parts from front to back. All trilobites are marine, most of them live in benthic habitat, and a few of them live in sand or drift. It appeared in the early Cambrian, with a large number of species and species. It reached its peak in the late Cambrian, and the Ordovician was still very prosperous. It began to decline after entering the Silurian, and completely disappeared at the end of the Permian. From the back, the trilobite is oval or oval, and the adult is 3-10 cm long and 1-3 cm wide. Smaller than 6 mm. The trilobite body is wrapped with a layer of shell, and the hard shell is the dorsal shell and its ventral edge. The ventral joint is chitin, and other parts are covered by soft film. Generally, the trilobite fossils collected are dorsal shells. The middle part of the trilobite's dorsal shell is called the axis or the central axis, and the left and right sides are called the rib leaves or ribs. The trilobite shell is smooth. Or there are pits, tumor packages, spots, radial lines, concentric lines, short spikes, etc. Most of the head is longitudinally divided into three lobes by two dorsal grooves, the middle part is the saddle and neck ring, the two sides are the cheeks, and the eyes are located in the cheeks. The buccal part is crossed by the facial line. The inner part between the two lines is collectively referred to as the skull, and the two sides are referred to as the movable cheek or free cheek. The thorax is composed of several thoracic segments with different shapes, and adults have 2-40 segments. The middle part is the central axis, and the two sides are called ribs. There are rib grooves on each rib node and intercostal grooves between the two rib nodes. The tail is formed by the fusion of several body segments, ranging from 1 to 30. The shape is generally semi-circular, but it varies greatly. It can be divided into a central axis and two ribs. Ribs are segmented, with rib groove and intercostal groove. Ribs may have edges, and there are often marginal spines on the edges. The class trilobites can be divided into 7 orders: Glomerozera, Ledelichia, Corydoptera, Brachynchoptera, Hymenoptera, Schizoptera, and Ribotidae. The trilobites are symbiotic with marine corals, sea lilies, brachiopods, cephalopods, etc. Most of them are adapted to the life of crawling or semi-swimming on the shallow seabed, and some are swimming or floating in the ocean. They feed on small organisms such as protozoa, sponges, coelenterates, brachiopods, or algae.
Price: 49.99 USD
Location: nanyangshi
End Time: 2025-01-22T07:46:10.000Z
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