This from History of Anchors...I do not necessarily agree with some of the conclusions but I believe the dates are accurate.
Anchors developed rapidly from the first half of the 20th century, with the advent of the
"CQR", developed by
Geoffrey Ingram Taylor of
Scotland in the early 1930s, now manufactured by Lewmar.
American Richard Danforth invented and developed the
"Danforth" pattern in the 1940s, a return to the symmetrical concept but with very large flat plate flukes. This anchor offers very good holding power for its weight (high efficiency) but does not perform well in other respects, meaning that it is not a good general purpose anchor. The original Danforth is still manufactured and sold by Tie Down Engineering in the USA.
Peter Bruce of the
Isle of Man in the UK developed the claw-type
"Bruce" anchor in the 1970s. Bruce Anchor Co has its primary role in the very large anchor business, producing mooring anchors and permanent installation types for heavy industry, such as oilrigs. On the back of this reputation, the Bruce small boat anchor type was initially very successful, and represented some significant improvements over the CQR.
New generation anchors have come into force since the latter part of the 20th century. The German "Buegelanker" features a simple single flat triangular fluke, with a roll-bar to ensure correct setting. A surprisingly simple design, this has proven more effective than its ancestors. Frenchman Alain Poiraud developed the "Spade" anchor in the 1990s, a huge leap in performance over any types which proceeded it. The Spade was the first anchor to successfully make use of a concave fluke, which provides the greatest efficiency (as opposed to the convex "plow" type of the CQR, or the flat "plate" type of the Danforth).