Lazarussuchus
Encyclopedia
Lazarussuchus is a genus
of basal
choristodere
, a type of amphibious
reptile, from the late Oligocene
and early Miocene
of France
and the Czech Republic
. Two species have been named: the type species
L. inexpectatus ("unexpected") (Hecht, 1992) from the late Oligocene of France; and L. dvoraki (for Zdeněk Dvořák), from the early Miocene of the Czech Republic. It was not a large animal; the skull of L. inexpectatus was only about 4.53 centimeters long (1.78 in).
that has widely-separated appearances in the fossil record, due to observational artifacts from either (local) extinction
and later reintroduction, or sampling artifacts
. In the case of choristoderes, the group was thought to have gone extinct in the Eocene
; however, Lazarussuchus illustrated that they persisted for millions of years after this as small, lizard-like animals. Additionally, because Lazarussuchus appears to have been a very basal choristodere based on phylogenetic analyses
, more basal than Late Cretaceous
choristoderes and perhaps even more basal than the possible Late Triassic
choristodere Pachystropheus
, there is the implication of a lengthy ghost lineage
of small choristoderes that have not been found or recognized. Evans and Klembara, in their description of L. dvoraki, further postulated that based on the climatic history of Europe in the Miocene and onward, and the fossil record of other European reptiles, small choristoderes could have persisted for longer than the early Miocene; marked cooling did not set in until the late Pliocene
.
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of basal
Basal (phylogenetics)
In phylogenetics, a basal clade is the earliest clade to branch in a larger clade; it appears at the base of a cladogram.A basal group forms an outgroup to the rest of the clade, such as in the following example:...
choristodere
Choristodera
Choristodera is an order of semi-aquatic diapsid reptiles which ranged from the Middle Jurassic, or possibly Late Triassic, to at least the early Miocene. Choristoderes have been found in North America, Asia, and Europe. The most common fossils are typically found from the Late Cretaceous to the...
, a type of amphibious
Amphibious
Amphibious means able to use either land or water. In particular it may refer to:*Amphibious warfare, warfare carried out on both land and water*Amphibians, vertebrate animals of the Class Amphibia...
reptile, from the late Oligocene
Oligocene
The Oligocene is a geologic epoch of the Paleogene Period and extends from about 34 million to 23 million years before the present . As with other older geologic periods, the rock beds that define the period are well identified but the exact dates of the start and end of the period are slightly...
and early Miocene
Miocene
The Miocene is a geological epoch of the Neogene Period and extends from about . The Miocene was named by Sir Charles Lyell. Its name comes from the Greek words and and means "less recent" because it has 18% fewer modern sea invertebrates than the Pliocene. The Miocene follows the Oligocene...
of France
France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...
and the Czech Republic
Czech Republic
The Czech Republic is a landlocked country in Central Europe. The country is bordered by Poland to the northeast, Slovakia to the east, Austria to the south, and Germany to the west and northwest....
. Two species have been named: the type species
Type species
In biological nomenclature, a type species is both a concept and a practical system which is used in the classification and nomenclature of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the species...
L. inexpectatus ("unexpected") (Hecht, 1992) from the late Oligocene of France; and L. dvoraki (for Zdeněk Dvořák), from the early Miocene of the Czech Republic. It was not a large animal; the skull of L. inexpectatus was only about 4.53 centimeters long (1.78 in).
Lazarus taxon
A Lazarus taxon is a taxonTaxon
|thumb|270px|[[African elephants]] form a widely-accepted taxon, the [[genus]] LoxodontaA taxon is a group of organisms, which a taxonomist adjudges to be a unit. Usually a taxon is given a name and a rank, although neither is a requirement...
that has widely-separated appearances in the fossil record, due to observational artifacts from either (local) extinction
Extinction
In biology and ecology, extinction is the end of an organism or of a group of organisms , normally a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and recover may have been lost before this point...
and later reintroduction, or sampling artifacts
Sampling (statistics)
In statistics and survey methodology, sampling is concerned with the selection of a subset of individuals from within a population to estimate characteristics of the whole population....
. In the case of choristoderes, the group was thought to have gone extinct in the Eocene
Eocene
The Eocene Epoch, lasting from about 56 to 34 million years ago , is a major division of the geologic timescale and the second epoch of the Paleogene Period in the Cenozoic Era. The Eocene spans the time from the end of the Palaeocene Epoch to the beginning of the Oligocene Epoch. The start of the...
; however, Lazarussuchus illustrated that they persisted for millions of years after this as small, lizard-like animals. Additionally, because Lazarussuchus appears to have been a very basal choristodere based on phylogenetic analyses
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...
, more basal than Late Cretaceous
Late Cretaceous
The Late Cretaceous is the younger of two epochs into which the Cretaceous period is divided in the geologic timescale. Rock strata from this epoch form the Upper Cretaceous series...
choristoderes and perhaps even more basal than the possible Late Triassic
Late Triassic
The Late Triassic is in the geologic timescale the third and final of three epochs of the Triassic period. The corresponding series is known as the Upper Triassic. In the past it was sometimes called the Keuper, after a German lithostratigraphic group that has a roughly corresponding age...
choristodere Pachystropheus
Pachystropheus
Pachystropheus is a genus of prehistoric reptile, probably a choristodere , from the Rhaetian of southwestern England...
, there is the implication of a lengthy ghost lineage
Ghost lineage
A ghost lineage is a phylogenetic lineage that is inferred to exist but has no fossil record....
of small choristoderes that have not been found or recognized. Evans and Klembara, in their description of L. dvoraki, further postulated that based on the climatic history of Europe in the Miocene and onward, and the fossil record of other European reptiles, small choristoderes could have persisted for longer than the early Miocene; marked cooling did not set in until the late Pliocene
Pliocene
The Pliocene Epoch is the period in the geologic timescale that extends from 5.332 million to 2.588 million years before present. It is the second and youngest epoch of the Neogene Period in the Cenozoic Era. The Pliocene follows the Miocene Epoch and is followed by the Pleistocene Epoch...
.
External links
- Ghost lineages - brief article on the fossil record of choristoderes