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Lacewing larvae in the Cretaceous were more diverse in appearance than they are today, best documented by numerous fossils preserved in amber. One morphotype of an unusual larva from about 100 Ma old Kachin amber (Myanmar) was formally recognised as a distinct group called Ankyloleon. The original description erected a single formal species, Ankyloleon caudatus. Yet, it was indicated that among the five original specimens, more species were represented. We here report five new specimens. Among these is the so far largest as well as the so far smallest specimen. Based on this expanded material we can estimate certain aspects of the ontogenetic sequence and are able to recognise a second discrete species, Ankyloleon caroluspetrus sp. nov. We discuss aspects of the biology of Ankyloleon based on newly observed details such as serrations on the mandibles. Long and slender mouthparts, legs and body together with a weakly expressed outer trunk segmentation provide indications for a lifestyle hunting for prey in more confined spaces. Still many aspects of the biology of these larvae must remain unclear due to a lack of a well comparable modern counterpart, emphasising how different the fauna of the Cretaceous was.
Polychelidan lobsters (Decapoda: Polychelida) are crustaceans with extant species which are restricted to deep water environments. Fossil species, however, used to live in more varied palaeoenvironments, from shallow water to deep water, and were more diverse morphologically. We redescribe two species of polychelidan lobsters, the Late Triassic Rosenfeldia triasica Garassino, Teruzzi & Dalla Vecchia, 1996 and the Late Jurassic Eryon oppeli Woodward, 1866, recently assigned to the same genus, Rosenfeldia, based upon only a few characters. Our investigation of all available material of both species leads us to distinguish these two species and to erect Rogeryon gen. nov. to accommodate Eryon oppeli. The palaeobiology of both species is interpreted for the first time. Rosenfeldia triasica with its stout first pereiopods and mandibles with both incisor and molar processes (documented for the first time in Polychelida) was benthic and probably fed either on slow-moving sedentary preys or was a scavenger. Rogeryon oppeli gen. et comb. nov. was benthic, visually adapted to shallow water palaeoenvironments, and possibly had a diet similar to that of slipper lobsters and horseshoe crabs. The redescription of these two species highlights the palaeobiological diversity of fossil polychelidans.