T. Rex and the Crater of Doom

Walter Alvarez’s father, Luis W. Alvarez (1911-1988), was an American experimental physicist. He is best known for his contributions to the Manhattan Project and for winning the 1968 Nobel Prize for Physics. Like his son, he was a professor at the University of California, Berkeley. In his book, Walter Alvarez describes his father as an important supporter of his impact hypothesis research. Luis W. Alvarez helped his son’s research by using his professional connections at Berkeley to test rock samples and consulted with other Berkeley scientists to discuss the impact theory and its evidence, always sharing his ideas with his son.

A nuclear chemist, Frank Asaro (1927-2014) worked at Lawrence Berkeley National Laboratory at the University of California, Berkeley. Asaro was instrumental in helping Walter Alvarez process rock samples from the KT boundary layer. Asaro measured trace elements in the rock, helping Alvarez learn that iridium was present in the rock layers from this time period. Alvarez credits Asaro’s laboratory work with helping him piece together the clues about the dinosaur extinction: “We know today what killed the dinosaurs because of Frank Asaro’s ability to make these remarkable measurements” (67).

Canadian geologist Alan Hildebrand (born in 1955) is a Canadian geologist who researched the KT boundary for his graduate thesis at the University of Arizona. In the late 1980s, Hildebrand’s research took him to the Brazos River tsunami bed in Texas, which he inferred must have been caused by a tsunami that began south of Texas. Hildebrand was aware of the impact hypothesis and reasoned that the asteroid impact that caused the tsunami must have been somewhere in the Gulf of Mexico. He eventually located the Yucatan impact site and collaborated with oil company geologists Glen Penfield and Antonio Camargo to publish a paper proposing that the Chicxulub crater was a Cretaceous/Tertiary (KT) boundary crater. Alvarez credits Hildebrand for locating the crater and praises his scientific insights and persistent nature, calling him a “relentless detective” (109).

Mexican geologist Jose Manuel Grajales worked for the Mexican Petroleum Institute, which is the research branch of Mexican oil company PEMEX (Petroleos Mexicanos). Grajales located the rock samples that the Petroleum Institute had taken from the Chicxulub crater via deep drilling. By sharing these samples with Alvarez and his colleagues, Grajales helped them confirm that this site had impact-melt rocks and was the site of an asteroid impact. Alvarez credits Grajales for his persistent efforts to locate these rocks in the company’s archives and for his willingness to share them with researchers. Alvarez later collaborated with Grajales during field work in Mexico, relying on Grajales’s local knowledge and geological insights to find the right rock outcroppings to study.

Author of the Foreword to T. Rex and the Crater of Doom, Carl Zimmer (born in 1966) is an American science journalist who has contributed to numerous magazines such as Discover Magazine, Scientific American, and The Atlantic. He is a regular contributor to The New York Times, covering biology and other science topics. In addition, Zimmer is an adjunct professor at Yale University, where he teaches biology and writing. In his Foreword, Zimmer reveals his personal and professional interest in Alvarez’s work, which he feels is “one of the great discoveries in the modern history of geology and paleontology” (ix).

Dutch paleontologist Jan Smit (born in 1943) researched the KT boundary rock layer in the 1980s. Alvarez explains that as he was developing his own impact hypothesis, Jan Smit also found evidence of iridium in his rock samples from Caravaca, Spain, and agreed with Alvarez that it was evidence of a catastrophic event. After years of consulting with each other on their ideas, the two later collaborated in Mexico at the Chicxulub site. Alvarez praises Smit’s careful research and his willingness to openly collaborate, calling him “the codiscoverer of the evidence for impact” (79).