''Bauruoolithus'' 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 fossilized eggs belonging to an extinct

crocodyliform Crocodyliformes is a clade of crurotarsan archosaurs, the group often traditionally referred to as "crocodilians". They are the first members of Crocodylomorpha to possess many of the features that define later relatives. They are the only ps ...

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'', ...

(

late Campanian The Campanian is the fifth of six ages of the Late Cretaceous Epoch on the geologic timescale of the International Commission on Stratigraphy (ICS). In chronostratigraphy, it is the fifth of six stages in the Upper Cretaceous Series. Campanian ...

early 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 interval from ...

) of

Brazil Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...

. ''Bauruoolithus'' eggs were most likely laid by the

notosuchia Notosuchia is a suborder of primarily Gondwanan mesoeucrocodylian crocodylomorphs that lived during the Jurassic and Cretaceous. Some phylogenies recover Sebecosuchia as a clade within Notosuchia, others as a sister group (see below); if Sebec ...

n crocodyliform ''

Baurusuchus ''Baurusuchus'' is an extinct member of the ancestral crocodilian lineage, which lived in Brazil from 90 to 83.5 million years ago, in the Late Cretaceous period. Technically, it is a genus of baurusuchid mesoeucrocodylian. It was a terres ...

''. Eggs of ''Bauruoolithus'' were described in 2011 from the

Adamantina Formation The Adamantina Formation is a geological formation in the Bauru Basin of western São Paulo state, in southeastern Brazil. Its strata date back to the Late Cretaceous epoch of the Cretaceous Period, during the Mesozoic Era. The formation is par ...

. The

type Type may refer to: Science and technology Computing * Typing, producing text via a keyboard, typewriter, etc. * Data type, collection of values used for computations. * File type * TYPE (DOS command), a command to display contents of a file. * Ty ...

oospecies 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 ...

is ''B. fragilis''.

Description

''Bauroolithus'' eggs are elongated, with a width measuring about half that of its height. The ends of the egg are blunt. At 0.15 to 0.25 millimeters in thickness, the shell is thin and somewhat wavy. The eggshell is divided into wedge-shaped shell units, which are pieces of

calcareous Calcareous () is an adjective meaning "mostly or partly composed of calcium carbonate", in other words, containing lime or being chalky. The term is used in a wide variety of scientific disciplines. In zoology ''Calcareous'' is used as an a ...

aggregate. The surface of the shell is covered in small tear-shaped pores.

Paleobiology

''Bauroolithus'' eggs belong to the crocodyloid basic egg type. Overall, their morphology is similar to that of the eggs of living

crocodylia 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 ...

ns. The eggs of living crocodylians undergo degradation over their incubation period so that hatchlings can easily break through the shells. Some fossils of ''Bauroolithus'' in Brazil are most likely from eggs that already hatched, but none show any signs of extensive degradation. This suggests that hatchlings broke through egg shells that were so thin that degradation was not necessary.

References

Egg fossils Reptile trace fossils Campanian life Maastrichtian life Late Cretaceous crocodylomorphs of South America Cretaceous Brazil Fossils of Brazil Adamantina Formation Fossil parataxa described in 2011 {{eggshell-stub