- CHINESE DINOSAUR EGGS
- General Discussion by Florence Magovern
- Click images to zoom
Taxonomic nomenclature of dinosaur eggs is based on thin
section analysis of shell fragments. There are four main parataxonomic
families of eggs found in Henan Basin, Xixia County, China (1)
Faveoloolithidae, (2) Dendroolithidae (3) Spheroolithidae and
(4) Elongatoolithidae. Members of the parataxonomic family Faveoloolithidae
were found in the earliest (deepest deposits) 20 meters below
ground level and have a shell morphotype that is relatively primitive
in comparison with the others. Members of the Spheroolithidae
family are most commonly found in the middle layer of the egg
bearing beds which were deposited in the middle of late Cretaceous
period. The 17 inch long eggs of the Elongatoolithidae family
were most commonly found in the upper layer associated with the
most recent or latest of the late Cretaceous. (Zhao Zikui, 1979).
Smaller examples (approximately 6 inches in length) of the Elongatoolithidae
family are found in the Nanxiong Basin in Guangdong Province.
The fossilized remains of dinosaur eggs are, in most cases,
limited to the egg shell. The embryos themselves were rarely
preserved. The morphology and structure of the egg shells reveal
few clues which can be cited to justify naming which taxon produced
them. Only with fossilized remains of embryos in relatively advanced
stages of development, can we begin to associate dinosaur types
with fossilized eggs and egg shells.
Shell morphology is the basis that is used in naming the
egg types. The structure of the shell in thin section analysis
is used to identify the taxonomic family. The late Karl Hirsch
was one of the leading experts in this country on eggs and eggshell
fragments. He examined several shell fragments. These shell fragments
were taken from several different types of dinosaur eggs from
Henan Province, China. The following summary is based on thin
section analysis and Chinese research papers.
The round, "cantaloupe" size and shape eggs with
dark brown shells are the most common found in China. To date,
no embryoinic remains have been found to identify the species
of dinosaur. Instead, these eggs are classified by shell morphotype.
The first shell morphotype is known as Dendrolithus. The shell
has a continuous layer at the surface. The following nomenclature
is used to refer to these dark brown cantaloupe shaped eggs.
Parataxonomic family - Dendroolithidae
Genus sp. - Dendroolithus sp.
Formation - Kaoguo
Age: Late Cretaceous
Location: Xixia Basin, Henan Province, China
The shell structure of these eggs is said to be Dendrospherulitic.
The pore system is Prolatocanaliculate. These are the most common
type of egg found in China. All shell fragments we collected
during our visit to the newly discovered egg site in Central
China were of this type. The Dendrospherulitic eggs appear to
be related to the taxonomic group Ornithopoda?? We continue to
search for embryonic remains as proof. At present these assumptions
are based on comparisons with egg shell fragments found together
with fossilized embryos and hatchlings found at other dinosaur
nesting sites around the world. The vast majority of the eggs
found in China are actually hatched. Click
here to see a ct scan of one of these eggs showing the "hatching
A second, more rare type of eggs found in central
China, is classified as Faveoloolithidae, Faveoloolithus sp.
with the remaining information the same. They have the thickest
shells of all the eggs from China. They are slightly larger in
size than the Dendrolithus, generally flatter and have a rougher
more undulating shell texture. The structural morphotype is named
Filispherulitic. The pore system is multicanaliculate and there
is no continuous layer at the surface of the shell.
The Chinese have published data which indicate that these
eggs are most commonly found in the earliest of the late Cretaceous
deposits, and that the prevailing climate of the period was hot
and humid. Several species of sauropods inhabited China during
the late Cretaceous.
The third major taxonomic family of dinosaur eggs found in
Henan Province is Spheroolithidae. This type of egg is generally
smaller in size with diameters ranging from 3 to 5 inches. The
most notable feature is that the shell is often thin.
Parataxonomic family - Spheroolithidae
Genus sp. - Spheroolithus sp.
Formation - Kaoguo and Majiachun
Age: Late Cretaceous
Location: Xixia County, Henan Province, China
The shell structural morphotype is Prolatospherulitic with
a pore system named prolatocanaliculate. Recent discoveries of
embryos in one type of egg from China having this shell morphotype
prove that the smaller eggs of this group are from a Therizinosaur
called Segnosaur. These small round eggs formally called Oolithus
by Chinese scientists are unique because of the calcite replacement
of the egg contents. This created conditions ideal for the preservation
of embryonic bones.
Therizinosaurs ("Scythe reptile") were named for
their large bony claws. An aberrant group of theropod dinosaurs
which, based on tooth structure, appear to be vegetarian yet
sport a most formidable hand claw. One of the claws from the
hand found in Asia measures 28 inches and this does not include
the horny part of the claw which would have made it even longer!
Just what these claws were used for is a mystery.
The photo here at right (click the image for a zoom) of a
Segnosaur embryo exposed by a careful acid etching technique
developed by Terry Manning of the Dinosaur Embryo Project, Leicester,
Great Britain. Click here to learn
more about Manning's work. See the May 1996 National Geographic
Magazine for a color photo of this specimen.
The fourth major type of eggs from China are elongated eggs
from Henan Province. They are classified in the parataxonomic
family Elongatoolithidae. The name describes the shape of the
egg and not the shell structure as in previously named groups.
The largest dinosaur eggs found to date in the world, Macroolithus
sp., are members of this family. Photo in May 1996 National Geographic,
Nests of Elongatus eggs found in various locations in China
indicate the eggs were laid in radial nests buried in sand or
mud in layers as many as three deep. The eggs were evidently
laid two at a time. The pairs of eggs were generally oriented
at 40 degree angles from the next nearest pair forming a radial
spiraling nest with each successive layer buried with a layer
of sand or mud. Macroolithus, named for its relative size are
found only in the upper strata or most recent deposit in Xixia
Basin. The following information relates to this type:
Parataxonomic family - Elongatoolithidae
Genus sp. - Macroolithus sp.
Formation - Shiguo
Age: Late Cretaceous
Location: Xixia Basin, Henan Province, China
The basic type of eggshell grouping is Ornithoid with a ratite
morphotype. The pore system is Angusticanaliculate. The Ornithoid
or ratite grouping includes fossil eggshell linked to Theropods.
Our "Dinosaur Baby Louie" is associated with a nest
of this type of eggs. Living ornithoids including ostrich eggs
and other large present day flightless bird eggs also have a
ratite egg shell structure.
One additional type of dinosaur egg found in China comes
from the Southern part in a area known as the Nanxiong Basin,
a full days ride (100 km) on back roads north of Guangzhou. These
elongated eggs also have a ratite shell structure but are much
smaller than the Macroolithus eggs discussed previously.
Parataxonomic Family: Elongatoolithidae
Genus species: Elongatoolithus sp.
Age: Late Cretaceous
Location: Guangdong Province, China
Identification by association: Raptor Type
Mark Norrell and others at the American Museum of Natural
History have found similar eggs during expeditions to Mongolia.
The photo shown here on the right from the cover of Science Magazine
Vol. 266 November 4, 1994 shows an embryo preserved inside of
one of these elongated eggs. The embryo found in this egg has
been identified as an oviraptor.
The oviraptor (Egg Thief) was first described by Henry Fairfield
Osborn during his 1920 expedition to Mongolia. The skull of one
of these dinosaurs was found crushed and on the top of a nest
of what was long believed to be a nest of Protoceratops eggs.
Osborn speculated that the skull was crushed by an enraged Ceratopsian
parent who caught the the unfortunate "raptor" in the
act of stealing eggs.
The photo here on the left, from the cover of Nature Magazine,
December 21-28, 1995 Volume 378, shows the mother Oviraptor shielding
her nest from the unfortunate disaster which recorded this moment
in time. It's discovery in 1993, again by a team of researchers
from the American Museum of Natural History, is proof that this
was, in fact, a caring parent defending her nest !
One final point of interest relating to dinosaur eggs in
general .....Chinese scientists have conducted studies of changes
in egg shell thickness over time. Comparison of shell thickness
of eggs found in deepest egg deposits with those of the same
species found nearer to the surface show a gradual thinning of
the shells over time (Zhao Zikui, October 1978). Samples of pollen
found in these deposits show a concurrent change in vegetation.
This evidence shows a gradual change in climate from humid subtropical
to an arid temperate one (Zhao Zikui, 1979). Thinning of egg
shells due to environmental stresses in modern birds like the
brown pelican has been shown to significantly reduce bird egg
viability and could lead to eventual extinction of the species.
Changes in climate and vegetation could have weakened the dinosaurs
ability to produce viable eggs and hence could have led to their
eventual extinction. A paper presented at the 1993 meeting of
the Geological Society of America introduced a new theory that
the percentage of oxygen in the atmosphere some 120 million years
ago (Early Cretaceous) diminished significantly over a period
of .5 million years. The percentage of oxygen measured in air
trapped in amber went from a high of 35 percent to a low of 28
percent. Extrapolating these findings over time, one could speculate
on a cause and effect relationship with the gradual changes in
shell thickness observed by the Chinese scientists.
In August of 1995, we were very fortunate to be able to escort
Dr. Philip Currie, Louie Psihoyos and John Knoebber to a recently
discovered dinosaur egg site in Central China While Louie shot
photos, Dr. Currie and Florence mapped 183 specimens of Dendroolithus
eggs in and around a village situated at the base of Green Dragon
Mountain. One of the photos taken by Louie during this visit
is included in the Dinosaur Egg story in the May 1996 issue of
National Geographic. The site is protected by the Chinese government.
were allowed two hours to observe and measure....the culmination
of a 10 day journey over the backroads of China. Charlie, here
on the left, found one of the few complete eggs in the field.
Most were cavities where eggs had been. Chinese officials watched
carefully to see that nothing was removed from the site. We hope
to return someday to have another look.