''Gannanoolithus'' (meaning "
Gannan stone egg") is an
oogenus
Egg fossils are the fossilized remains of eggs laid by ancient animals. As evidence of the physiological processes of an animal, egg fossils are considered a type of trace fossil. Under rare circumstances a fossil egg may preserve the remains of t ...
of
dinosaur egg
Dinosaur eggs are the organic vessels in which a dinosaur embryo develops. When the first scientifically documented remains of non-avian dinosaurs were being described in England during the 1820s, it was presumed that dinosaurs had laid eggs be ...
s likely laid by a
dromaeosaurid
Dromaeosauridae () is a family of feathered theropod dinosaurs. They were generally small to medium-sized feathered carnivores that flourished in the Cretaceous Period. The name Dromaeosauridae means 'running lizards', from Greek ('), meaning ...
theropod. It contains a
single oospecies, ''G. yingliangi'', known from the
Late Cretaceous
The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', ...
(
Maastrichtian
The Maastrichtian () is, in the ICS geologic timescale, the latest age (uppermost stage) of the Late Cretaceous Epoch or Upper Cretaceous Series, the Cretaceous Period or System, and of the Mesozoic Era or Erathem. It spanned the interv ...
)
Lianhe Formation of
Jiangxi Province
Jiangxi (; ; formerly romanized as Kiangsi or Chianghsi) is a landlocked province in the east of the People's Republic of China. Its major cities include Nanchang and Jiujiang. Spanning from the banks of the Yangtze river in the north into hi ...
, China.
Etymology
The
generic name, ''Gannanoolithus'', combines "Gannan", an alternate name of
Ganzhou City where the fossils were found, with the suffix "‑oolithus", meaning "stone egg". The
specific name Specific name may refer to:
* in Database management systems, a system-assigned name that is unique within a particular database
In taxonomy, either of these two meanings, each with its own set of rules:
* Specific name (botany), the two-part (bino ...
, ''yingliangi'', honors the Yingliang Stone Natural History Museum, where the fossils are housed. The authors also used the binomial variation "''Ganzhouoolithus yingliangensis''" in a figure in their publication.
Description
The ''Gannanoolithus''
holotype
A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of seve ...
specimen,
YLSNHM 01579, consists of a
clutch
A clutch is a mechanical device that engages and disengages power transmission, especially from a drive shaft to a driven shaft. In the simplest application, clutches connect and disconnect two rotating shafts (drive shafts or line shafts ...
of eight eggs. Specimens
CUGW EH067-1 (a single egg) and EH067-2 (a pair of eggs) were also referred to the oogenus. All of the known fossil eggs have been found in layers of the
Lianhe Formation in the Shahe Industrial Zone of
Ganzhou City in
Jiangxi Province
Jiangxi (; ; formerly romanized as Kiangsi or Chianghsi) is a landlocked province in the east of the People's Republic of China. Its major cities include Nanchang and Jiujiang. Spanning from the banks of the Yangtze river in the north into hi ...
, China. The eggs are symmetrically elliptic, ranging in size from long. The eggshells are thick. Similar to the preserved eggshells of ''
Deinonychus
''Deinonychus'' ( ; ) is a genus of Dromaeosauridae, dromaeosaurid Theropoda, theropod dinosaur with one described species, ''Deinonychus antirrhopus''. This species, which could grow up to long, lived during the early Cretaceous Period (geo ...
''-like
maniraptora
Maniraptora is a clade of coelurosaurian dinosaurs which includes the birds and the non-avian dinosaurs that were more closely related to them than to '' Ornithomimus velox''. It contains the major subgroups Avialae, Deinonychosauria, Ovirapt ...
n theropods, they demonstrate an
angusticanaliculate pore system. The porosity of ''Gannanoolithus'' eggs is similar to that of
extant
Extant is the opposite of the word extinct. It may refer to:
* Extant hereditary titles
* Extant literature, surviving literature, such as ''Beowulf'', the oldest extant manuscript written in English
* Extant taxon, a taxon which is not extinct, ...
crocodilians
Crocodilia (or Crocodylia, both ) is an order of mostly large, predatory, semiaquatic reptiles, known as crocodilians. They first appeared 95 million years ago in the Late Cretaceous period ( Cenomanian stage) and are the closest living ...
and
galliforms
Galliformes is an order of heavy-bodied ground-feeding birds that includes turkeys, chickens, quail, and other landfowl. Gallinaceous birds, as they are called, are important in their ecosystems as seed dispersers and predators, and are often r ...
, whose nests are typically covered.
Paleobiology
Due to similarities with North American fossil eggs, ''Gannanoolithus'' eggs were likely laid by a dromaeosaurid. Notably, the eggs are paired in the holotype clutch, which has been observed in some other ootaxa. This may indicate that the egg layer had paired functional oviducts, as has been suggested for
troodontids
Troodontidae is a clade of bird-like theropod dinosaurs. During most of the 20th century, troodontid fossils were few and incomplete and they have therefore been allied, at various times, with many dinosaurian lineages. More recent fossil disco ...
and
oviraptorosaurs
Oviraptorosaurs ("egg thief lizards") are a group of feathered maniraptoran dinosaurs from the Cretaceous Period of what are now Asia and North America. They are distinct for their characteristically short, beaked, parrot-like skulls, with or w ...
.
Parataxonomy
In their
phylogenetic analyses
In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...
, Wu et al. (2024) found ''Gannanoolithus'' to occupy an uncertain position in relation to other dinosaur ootaxa. They recovered it in a
polytomy
An internal node of a phylogenetic tree is described as a polytomy or multifurcation if (i) it is in a rooted tree and is linked to three or more child subtrees or (ii) it is in an unrooted tree and is attached to four or more branches. A tr ...
of other theropod eggs which is the
sister taxon
In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree.
Definition
The expression is most easily illustrated by a cladogram:
Taxon A and ...
to oviraptorosaur eggs, most of which belong to the
Elongatoolithidae
Elongatoolithidae is an oofamily of fossil eggs, representing the eggs of oviraptorosaurs (with the exception of the avian ''Ornitholithus''). They are known for their highly elongated shape. Elongatoolithids have been found in Europe, Asia, and b ...
. Their results are displayed in the
cladogram
A cladogram (from Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an evolutionary tree because it does not show how ancestors are related to ...
below:
References
{{Taxonbar, from=Q125561712
Egg fossils
Fossils of China
Late Cretaceous reptiles of Asia
Fossil parataxa described in 2024