Sinornithosaurus form from those found on birds from the same geological deposits. The body (contour) feathers were generally between 3-4.5 cm long and included two types: the first type are formed of several filaments joined together into "tufts", similar to modern down feathers. The second type, including those on the arms, were composed of rows of filaments ("barbs") joined together along a main shaft ("rachis"), making them similar in structure to modern bird feathers. However, unlike the wing feathers of flying birds, they did not have the secondary branches with tiny little hooks ("barbules") that flight feathers have, which allow the
Calamus Swamp Calamus Swamp Calamus Swamp is a public preserve located from Circleville in Pickaway County, Ohio, United States. It has a natural kettle lake/wetland and is owned by the Columbus Audubon, the local chapter of Audubon. Calamus Swamp includes the only known kettle lake in Central Ohio that is naturally vegetated and undisturbed. The kettle lake was made in the last ice age by the glacier that covered 2/3 of Ohio. When Ada May Burke and Sally V. May got the land, they donated it to Columbus Audubon, who then made it into a public preserve. According to the Columbus Audubon