Dark matter is observed by the gravitational effect that  it has on radiation and the visible universe. The gravitational  force it has from dark matter plays a critical role in the shape of  the galaxies orbit and the because of the hot gases in the groups  of galaxies.
The Angus breed is perhaps the most used, most well-known breed of beef cattle in the U.S. With origins in northeast Scotland, Angus, also known as Black Angus, is popular among Brits and Americans and was first imported to the United States in 1873.
The truth of the Pit Bull breed is that they were bred for their aggressive traits. Anyone that denies that is clueless. Nice line up of dogs but this is not an accurate list of the most popular breeds in US. For example, English Cocker Spaniel ranks 62nd on the AKC list.