Dead Clade Walking
Encyclopedia
The phrase Dead Clade Walking refers to the fact that some clades
(groups) of organisms which survived mass extinctions, either become extinct a few million years after the mass extinction or fail to recover in numbers and diversity.
(2002) as a reference to Dead Man Walking
, a film whose title is based on USA prison slang
for a condemned prisoner's last walk to the execution chamber.
s was significantly higher in the stage (major subdivision of an epoch – typically 2–10 million years' duration) following a mass extinction than in the stages preceding the mass extinction. His analysis focused on marine mollusc
s since they constitute the most abundant group of fossils and are therefore the least likely to produce sampling error
s. Jablonski suggested that two possible explanations deserved further study:
"Dead Clade Walking" has since appeared in other scientists' writings about the aftermaths of mass extinctions.
Cladistics
Cladistics is a method of classifying species of organisms into groups called clades, which consist of an ancestor organism and all its descendants . For example, birds, dinosaurs, crocodiles, and all descendants of their most recent common ancestor form a clade...
(groups) of organisms which survived mass extinctions, either become extinct a few million years after the mass extinction or fail to recover in numbers and diversity.
Origin of phrase
The phrase "Dead Clade Walking" was coined by David JablonskiDavid Jablonski
David Jablonski is an American professor of geophysical sciences at the University of Chicago. His research focuses upon the ecology and biogeography of the origin of major novelties, the evolutionary role of mass extinctions—in particular the K-T extinction—and other large-scale processes in the...
(2002) as a reference to Dead Man Walking
Dead Man Walking (film)
Dead Man Walking is a 1995 American drama film directed by Tim Robbins, who adapted the screenplay from the non-fiction book of the same name...
, a film whose title is based on USA prison slang
Prison slang
Prison slang is an argot used primarily by criminals and/or detainees in correctional institutions. As might be expected, many of the terms deal with criminal behavior, sex or violence...
for a condemned prisoner's last walk to the execution chamber.
Evidence
Jablonski found that the extinction rate of marine invertebrateInvertebrate
An invertebrate is an animal without a backbone. The group includes 97% of all animal species – all animals except those in the chordate subphylum Vertebrata .Invertebrates form a paraphyletic group...
s was significantly higher in the stage (major subdivision of an epoch – typically 2–10 million years' duration) following a mass extinction than in the stages preceding the mass extinction. His analysis focused on marine mollusc
Mollusca
The Mollusca , common name molluscs or mollusksSpelled mollusks in the USA, see reasons given in Rosenberg's ; for the spelling mollusc see the reasons given by , is a large phylum of invertebrate animals. There are around 85,000 recognized extant species of molluscs. Mollusca is the largest...
s since they constitute the most abundant group of fossils and are therefore the least likely to produce sampling error
Sampling error
-Random sampling:In statistics, sampling error or estimation error is the error caused by observing a sample instead of the whole population. The sampling error can be found by subtracting the value of a parameter from the value of a statistic...
s. Jablonski suggested that two possible explanations deserved further study:
- Post-extinction physical environments differed from pre-extinction environments in ways which were disadvantageous to the "dead clades walking".
- EcosystemEcosystemAn ecosystem is a biological environment consisting of all the organisms living in a particular area, as well as all the nonliving , physical components of the environment with which the organisms interact, such as air, soil, water and sunlight....
s that developed after recoveries from mass extinctions may have been less favorable for the "dead clades walking".
"Dead Clade Walking" has since appeared in other scientists' writings about the aftermaths of mass extinctions.