George Olshevsky
Encyclopedia
George Olshevsky is a freelance editor
, writer
, publisher, amateur paleontologist, and mathematician
living in San Diego, California
.
Olshevsky maintains the comprehensive online Dinosaur Genera List. He is known as the originator of the Birds Came First hypothesis in the descent of birds debate, which states that all dinosaurs are the descendants of small, arboreal and perhaps flying ancestors.
Olshevsky is part of a collaborative effort to recognize and standardize terms used to describe uniform polychora and uniform polytope
s, the analogues of uniform polyhedra in four and higher dimensions.
, The Amazing Spider-Man
, Fantastic Four
, Marvel Team-Up
, etc.) mostly between 1976 and 1988, although he notes that beyond the 1976 date, he "never did manage to index every single Marvel superhero comic, just the more popular runs". Since that time, he does not think of himself as an active comics collector, although he notes that the impulse to index remains - his Dinosaur Genera List is "essentially an index to all the dinosaur names"; his Uniform Polychora website is "an index to all the convex uniform polychora" and his day job (as of the late 1990s/early 2000s) is freelance book indexing.
's Predatory Dinosaurs of the World, Olshevsky realized that the arguments expounded there for the secondarily flightlessness of the Maniraptora
might well be adapted to argue for the same condition in all Theropoda
, indeed in all Dinosauria.
"BCF" accepts the close relationship between dinosaurs and birds, but argues that, merely given this relationship, it is just as likely that dinosaurs descended from birds as the other way around. In this case the term "birds" refers to a morphological state, not to Aves as they have been cladistically
defined. Olshevsky does not claim that the branch leading to modern birds
split off from other dinosaurs very early; in fact precisely the opposite: he thinks that Aves is but the most derived expression of a vast diversification of flying dinosaurs all through the Jurassic
.
BCF admits that most dinosaurs found are large and very derived
in morphology
compared to a hypothetical flying ancestor, and it also accepts the results of cladistic analysis connecting these large species into a cladogram
, suggesting that the intermediate forms were also large. BCF could have avoided this problem by claiming that just a very basal form was volant and all subsequent forms large. Instead Olshevsky resorted to a far more radical position by emphasising the point that a cladogram doesn't logically imply the morphology of its intermediate steps. He claimed, basing himself partly on Cope's law, that there was a hidden stem lineage of small arboreal forms that during the Mesozoic
was the real engine driving dinosaurian evolution, generating time and again larger ground-dwelling species. The smallness and arboreality of the forms was used to explain the fact that they rarely left a trace in the fossil record. Of course being small and arboreal doesn't imply the capacity to fly and Olshevsky allowed his hypothesis to diverge in three subhypotheses: the weakest was that the stem line consisted of small tree-living species; the stronger was that these could glide; the strongest that they possessed full powered flight.
BCF has not found acceptance among professional paleontologists. It was only published twice, once in a magazine, Mesozoic Meanderings, which Olshevsky himself produced, and once in the popular-science magazine Omni
. Paul perfunctorily dismissed the hypothesis in his Dinosaurs of the Air; in the peer-reviewed literature it is never even mentioned as such. However this does not mean the hypothesis has been completely ignored by professionals. Olshevsky is a well-known figure among dinosaur enthusiasts in the USA and has been for many years a very active participant in the various internet fora dedicated to the study of dinosaurs. This has led to much debate about BCF. The main objections from the professional side are that the scenario as a whole is too vague to be testable and that the empirical support for the most interesting subhypothesis — full flight capacity — is poor. Only for the group of the Tetanurae
, which are already quite derived theropods, are there some slight indications, and these can be explained as exaptation
s. Because of the many convergences needed, BCF is also not very parsimonious when analysed from a cladistic point of view, as it implies that flight was lost many times. The parsimony problem would only be remedied if many flying forms would be found basal to the various groups. Current paleontological consensus is that dinosaurs started as, and largely remained, ground-dwelling forms, that most major branching points in Mesozoic dinosaurian phylogeny were not volant and that it were only the members of the derived dinosaurian clade Maniraptora that took to the trees — and to the air — during the Jurassic
.
Editing
Editing is the process of selecting and preparing written, visual, audible, and film media used to convey information through the processes of correction, condensation, organization, and other modifications performed with an intention of producing a correct, consistent, accurate, and complete...
, writer
Writer
A writer is a person who produces literature, such as novels, short stories, plays, screenplays, poetry, or other literary art. Skilled writers are able to use language to portray ideas and images....
, publisher, amateur paleontologist, and mathematician
Mathematician
A mathematician is a person whose primary area of study is the field of mathematics. Mathematicians are concerned with quantity, structure, space, and change....
living in San Diego, California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
.
Olshevsky maintains the comprehensive online Dinosaur Genera List. He is known as the originator of the Birds Came First hypothesis in the descent of birds debate, which states that all dinosaurs are the descendants of small, arboreal and perhaps flying ancestors.
Olshevsky is part of a collaborative effort to recognize and standardize terms used to describe uniform polychora and uniform polytope
Uniform polytope
A uniform polytope is a vertex-transitive polytope made from uniform polytope facets of a lower dimension. Uniform polytopes of 2 dimensions are the regular polygons....
s, the analogues of uniform polyhedra in four and higher dimensions.
Marvel Comics indexing
George Olshevsky was born on June 12, 1946, and for many years (particularly the 1960s to the 1980s) "collected Marvel Comics and compiled the Official Marvel Comics Index for Marvel," owning for 14 years "the world’s only complete collection of Marvel superhero comics that extended all the way back to Marvel’s first comic book, Marvel Comics #1, October–November 1939". While compiling the Marvel Indices, he "produced some 60 fully illustrated books, totaling more than a million and a quarter words," producing indices to all the major Marvel Superheroes (including AvengersAvengers (comics)
The Avengers is a fictional team of superheroes, appearing in magazines published by Marvel Comics. The team made its debut in The Avengers #1 The Avengers is a fictional team of superheroes, appearing in magazines published by Marvel Comics. The team made its debut in The Avengers #1 The Avengers...
, The Amazing Spider-Man
The Amazing Spider-Man
The Amazing Spider-Man is an American comic book series published by Marvel Comics, featuring the adventures of the fictional superhero Spider-Man. Being the mainstream continuity of the franchise, it began publication in 1963 as a monthly periodical and was published continuously until it was...
, Fantastic Four
Fantastic Four
The Fantastic Four is a fictional superhero team appearing in comic books published by Marvel Comics. The group debuted in The Fantastic Four #1 , which helped to usher in a new level of realism in the medium...
, Marvel Team-Up
Marvel Team-Up
Marvel Team-Up is the name of several American comic book series published by Marvel Comics. The series featured two or more Marvel characters in one story...
, etc.) mostly between 1976 and 1988, although he notes that beyond the 1976 date, he "never did manage to index every single Marvel superhero comic, just the more popular runs". Since that time, he does not think of himself as an active comics collector, although he notes that the impulse to index remains - his Dinosaur Genera List is "essentially an index to all the dinosaur names"; his Uniform Polychora website is "an index to all the convex uniform polychora" and his day job (as of the late 1990s/early 2000s) is freelance book indexing.
Birds Came First
The Birds Came First-hypothesis ("BCF") is a radical expansion of the possibility that some dinosaurs are secondarily flightless, arguing that all dinosaurs are "postvolant". The hypothesis, or ecomorphological and phylogenetic scenario, was developed by Olshevsky in the early nineties. Shortly after reading Gregory S. PaulGregory S. Paul
Gregory Scott Paul is a freelance researcher, author and illustrator who works in paleontology, and more recently has examined sociology and theology. He is best known for his work and research on theropod dinosaurs and his detailed illustrations, both live and skeletal...
's Predatory Dinosaurs of the World, Olshevsky realized that the arguments expounded there for the secondarily flightlessness of the Maniraptora
Maniraptora
Maniraptora is a clade of coelurosaurian dinosaurs which includes the birds and the dinosaurs that were more closely related to them than to Ornithomimus velox. It contains the major subgroups Avialae, Deinonychosauria, Oviraptorosauria and Therizinosauria. Ornitholestes and the Alvarezsauroidea...
might well be adapted to argue for the same condition in all Theropoda
Theropoda
Theropoda is both a suborder of bipedal saurischian dinosaurs, and a clade consisting of that suborder and its descendants . Dinosaurs belonging to the suborder theropoda were primarily carnivorous, although a number of theropod groups evolved herbivory, omnivory, and insectivory...
, indeed in all Dinosauria.
"BCF" accepts the close relationship between dinosaurs and birds, but argues that, merely given this relationship, it is just as likely that dinosaurs descended from birds as the other way around. In this case the term "birds" refers to a morphological state, not to Aves as they have been cladistically
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...
defined. Olshevsky does not claim that the branch leading to modern birds
Modern birds
Modern birds are the most recent common ancestor of all living birds and all its descendants.Modern birds are characterised by feathers, a beak with no teeth , the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a lightweight but strong skeleton...
split off from other dinosaurs very early; in fact precisely the opposite: he thinks that Aves is but the most derived expression of a vast diversification of flying dinosaurs all through the Jurassic
Jurassic
The Jurassic is a geologic period and system that extends from about Mya to Mya, that is, from the end of the Triassic to the beginning of the Cretaceous. The Jurassic constitutes the middle period of the Mesozoic era, also known as the age of reptiles. The start of the period is marked by...
.
BCF admits that most dinosaurs found are large and very derived
Derived
In phylogenetics, a derived trait is a trait that is present in an organism, but was absent in the last common ancestor of the group being considered. This may also refer to structures that are not present in an organism, but were present in its ancestors, i.e. traits that have undergone secondary...
in morphology
Morphology (biology)
In biology, morphology is a branch of bioscience dealing with the study of the form and structure of organisms and their specific structural features....
compared to a hypothetical flying ancestor, and it also accepts the results of cladistic analysis connecting these large species into a cladogram
Cladogram
A cladogram is a diagram used in cladistics which shows ancestral relations between organisms, to represent the evolutionary tree of life. Although traditionally such cladograms were generated largely on the basis of morphological characters, DNA and RNA sequencing data and computational...
, suggesting that the intermediate forms were also large. BCF could have avoided this problem by claiming that just a very basal form was volant and all subsequent forms large. Instead Olshevsky resorted to a far more radical position by emphasising the point that a cladogram doesn't logically imply the morphology of its intermediate steps. He claimed, basing himself partly on Cope's law, that there was a hidden stem lineage of small arboreal forms that during the Mesozoic
Mesozoic
The Mesozoic era is an interval of geological time from about 250 million years ago to about 65 million years ago. It is often referred to as the age of reptiles because reptiles, namely dinosaurs, were the dominant terrestrial and marine vertebrates of the time...
was the real engine driving dinosaurian evolution, generating time and again larger ground-dwelling species. The smallness and arboreality of the forms was used to explain the fact that they rarely left a trace in the fossil record. Of course being small and arboreal doesn't imply the capacity to fly and Olshevsky allowed his hypothesis to diverge in three subhypotheses: the weakest was that the stem line consisted of small tree-living species; the stronger was that these could glide; the strongest that they possessed full powered flight.
BCF has not found acceptance among professional paleontologists. It was only published twice, once in a magazine, Mesozoic Meanderings, which Olshevsky himself produced, and once in the popular-science magazine Omni
Omni (magazine)
OMNI was a science and science fiction magazine published in the US and the UK. It contained articles on science fact and short works of science fiction...
. Paul perfunctorily dismissed the hypothesis in his Dinosaurs of the Air; in the peer-reviewed literature it is never even mentioned as such. However this does not mean the hypothesis has been completely ignored by professionals. Olshevsky is a well-known figure among dinosaur enthusiasts in the USA and has been for many years a very active participant in the various internet fora dedicated to the study of dinosaurs. This has led to much debate about BCF. The main objections from the professional side are that the scenario as a whole is too vague to be testable and that the empirical support for the most interesting subhypothesis — full flight capacity — is poor. Only for the group of the Tetanurae
Tetanurae
Tetanurae, or "stiff tails", is a clade that includes most theropod dinosaurs, as well as birds. Tetanurans first appear during the early or middle Jurassic Period.-Definition:...
, which are already quite derived theropods, are there some slight indications, and these can be explained as exaptation
Exaptation
Exaptation, cooption, and preadaptation are related terms referring to shifts in the function of a trait during evolution. For example, a trait can evolve because it served one particular function, but subsequently it may come to serve another. Exaptations are common in both anatomy and behaviour...
s. Because of the many convergences needed, BCF is also not very parsimonious when analysed from a cladistic point of view, as it implies that flight was lost many times. The parsimony problem would only be remedied if many flying forms would be found basal to the various groups. Current paleontological consensus is that dinosaurs started as, and largely remained, ground-dwelling forms, that most major branching points in Mesozoic dinosaurian phylogeny were not volant and that it were only the members of the derived dinosaurian clade Maniraptora that took to the trees — and to the air — during the Jurassic
Jurassic
The Jurassic is a geologic period and system that extends from about Mya to Mya, that is, from the end of the Triassic to the beginning of the Cretaceous. The Jurassic constitutes the middle period of the Mesozoic era, also known as the age of reptiles. The start of the period is marked by...
.
Olshevsky's websites
- Dinosaur Genera List
- Dinosaur Home Page
- Polyhedra home page
- List of convex uniform polychora
- Multidimensional Glossary
Other links
- Dinosaur Detective: George "Dinogeorge" Olshevsky
- The birds first? A theory to fit the facts - evolution of reptiles into birds, Omni, June, 1994 by George Olshevsky
- REVIEW OF THE TYRANNOSAURIDAE by George Olshevsky
- Discovering Dinosaurs: 6 books by George Olshevsky & Sandy Fritz
- Hypothetical Dinobird