This extinction eliminated about half of marine invertebrate genera and left some groups with very few surviving species.
Over these geological timescales there have been at least five (Raup & Sepkoski, 1982; see also Harnik et al., 2012) relatively sudden (c. 1 10 Myr; Briggs, 1995) major marine extinctions, estimated to have eradicated at least half of marine species (Briggs, 2003; but see Bambach, 2006).
Roughly half of the marines charged with crimes in Iraq exhibit clear signs of post-traumatic stress disorder, a Marine defense lawyer said.
Defense Secretary Donald H. Rumsfeld signed a mammoth deployment order today sending about 35,000 new troops, half of them marines, to the Persian Gulf region, Pentagon and military officials said.
Although some fauna appear to have survived these events (see e.g. Thuy et al., 2012), in the most severe case approximately half of all marine families (Sepkoski, 1986) and more than 95% of marine species (Raup, 1979; Benton & Twitchett, 2003) disappeared.
Two hundred million years ago, at the end of the Triassic period, a mass extinction, often attributed to major volcanic activity, wiped out half of all marine life on Earth.
Only half of the marine division's 300 boats are in working order, observers say, and even those are often idle for want of fuel.
About half of the marine invertebrate genera went extinct at this time; whether land plants or terrestrial vertebrates suffered a similar extinction during this interval is unclear.
According to the federal Fish and Wildlife Service, one million of the world's 1.5 million aquarium hobbyists live in the United States, and Americans buy more than half of all marine aquarium fish sold globally.
More than half of the marine species on Earth disappeared.
