''Suchoolithus'' 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 ...

(fossil egg genus) of

crocodylomorph Crocodylomorpha is a group of pseudosuchian archosaurs that includes the crocodilians and their extinct relatives. They were the only members of Pseudosuchia to survive the end-Triassic extinction. During Mesozoic and early Cenozoic times, cro ...

eggs from the late

Jurassic The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately Mya. The J ...

Portugal Portugal, officially the Portuguese Republic, In recognized minority languages of Portugal: :* mwl, República Pertuesa is a country located on the Iberian Peninsula, in Southwestern Europe, and whose territory also includes the Macaronesian ...

. They are notable for their small size, and for being among the oldest known crocodylomorph eggs.

Description

''Suchoolithus'' is known from a single, well-preserved egg clutch of 13 eggs. The eggs have a blunt, ellipsoid shape, and are quite small (measuring only long by across). All but two of the eggs are arranged horizontally in the clutch. The eggshell is only 163 μm thick, and is sculpted with tiny, irregular bumps on its outer surface. Like other crocodylian eggs, its shell is composed of thousands of tiny calcium carbonate crystal units; in ''S. portucalensis'', these eggshell units are trapezoidal, tightly packed, and wider than they are tall. Russo ''et al.'' 2017 did not observe any pores openings on the eggshell's surface, though a possible pore canal was observed in one section of the shell.

History

Fossil crocodylian eggs are generally rare, though they have been discovered worldwide (excepting Antarctia and Australia). In 2008, the Portuguese paleontologist

Octávio Mateus Octávio Mateus (born 1975) is a Portuguese dinosaur paleontologist and biologist Professor of Paleontology at the Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa. He graduated in Universidade de Évora and received his PhD at ...

discovered a fossilized egg clutch at the

Lourinhã Formation The Lourinhã Formation () is a fossil rich geological formation in western Portugal, named for the municipality of Lourinhã. The formation is mostly Late Jurassic in age (Kimmeridgian/Tithonian), with the top of the formation extending into the ...

of Portugal that would later become

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 ...

of ''Suchoolithus''. These eggs were first described in 2014 by Russo, Mateus, Balbino, and Marzola, who at the time tentatively referred them to ''Krokolithes'', but noted their similarities to the Krokolithid ''

Bauruoolithus ''Bauruoolithus'' is an oogenus of fossilized eggs belonging to an extinct crocodyliform from the Late Cretaceous (late Campanian-early Maastrichtian) of Brazil. ''Bauruoolithus'' eggs were most likely laid by the notosuchian crocodyliform ''Baur ...

''. In 2016, João Russo, working with

as his supervisor and Balbino as co-supervisor, completed his Master's Thesis at

Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa The NOVA School of Science and Technology (FCT NOVA or NOVA SST) is a Portuguese faculty of the NOVA University Lisbon located at the ''Caparica Campus'', near Lisbon. The School operates with great autonomy and awards degrees in several engin ...

, in which he named the oogenus and oospecies ''Suchoolithus portucalensis'' (meaning "crocodile egg stone from Portugal"). The next year, Russo, Mateus, Marzola, and Balbino published the description of ''Suchoolithus'' in '' PLOS One''.

Paleobiology and paleoecology

''Suchoolithus'' is known exclusively from the upper

Tithonian In the geological timescale, the Tithonian is the latest age of the Late Jurassic Epoch and the uppermost stage of the Upper Jurassic Series. It spans the time between 152.1 ± 4 Ma and 145.0 ± 4 Ma (million years ago). It is preceded by t ...

of the Late Jurassic

of Portugal, making it (alongside ''

Krokolithes ''Krokolithes'' is an oogenus of Crocodiloid eggs. These eggs were laid by an extinct species of Crocodylian. It contains three oospecies: ''K. dinophilus'', ''K. wilsoni'' and ''K. helleri''. 1 Fossils of the oogenus have been found in the Olig ...

dinophilus'') the oldest known crocodylomorph egg. This formation, representing the deposits of

river delta A river delta is a landform shaped like a triangle, created by deposition of sediment that is carried by a river and enters slower-moving or stagnant water. This occurs where a river enters an ocean, sea, estuary, lake, reservoir, or (more ra ...

s and

alluvial fan An alluvial fan is an accumulation of sediments that fans outwards from a concentrated source of sediments, such as a narrow canyon emerging from an escarpment. They are characteristic of mountainous terrain in arid to semiarid climates, but a ...

s, has similar fauna and flora to the contemporaneous

Morrison Formation The Morrison Formation is a distinctive sequence of Upper Jurassic sedimentary rock found in the western United States which has been the most fertile source of dinosaur fossils in North America. It is composed of mudstone, sandstone, siltstone, ...

in the United States and the

Tendaguru Formation The Tendaguru Formation, or Tendaguru Beds are a highly fossiliferous formation and Lagerstätte located in the Lindi Region of southeastern Tanzania. The formation represents the oldest sedimentary unit of the Mandawa Basin, overlying Neoprote ...

in Tanzania. Several types of crocodylomorphs are known from the late Jurassic of Portugal, but given the small size of the eggs, it is most likely that ''Suchoolithus'' were laid by one of the smaller species (perhaps less than long), such as ''

Bernissartia ''Bernissartia'' ('of Bernissart') is an extinct genus of neosuchian crocodyliform that lived in the Early Cretaceous, around 130 million years ago. At only in length, ''Bernissartia'' is one of the smallest crocodyliforms that ever lived. It ...

'',

cf. The abbreviation ''cf.'' (short for the la, confer/conferatur, both meaning "compare") is used in writing to refer the reader to other material to make a comparison with the topic being discussed. Style guides recommend that ''cf.'' be used onl ...

Alligatorium ''Alligatorium'' is an extinct genus of atoposaurid crocodylomorph from Late Jurassic marine deposits in France. Systematics The type species In zoological nomenclature, a type species (''species typica'') is the species name with which the ...

'', ''

Lisboasaurus ''Lisboasaurus'' is a small (400 mm length) genus of Mesozoic crocodylomorph that lived in fresh water. It is known from fossilized tooth and jaw fragments of Late Jurassic and Early Cretaceous age. Two species have been described. In the pa ...

'', ''

Lusitanisuchus ''Lusitanisuchus'' is an extinct genus of mesoeucrocodylian crocodylomorph. Mostly fragmentary fossils have been found from several localities in Portugal and are Late Jurassic and Early Cretaceous in age. The only species, ''Lusitanisuchus mit ...

'', or ''

Theriosuchus ''Theriosuchus'' is an extinct genus of atoposaurid neosuchian from Late Jurassic to Early Cretaceous of Europe (Hungary & southern England), Southeast Asia (Thailand) and western North America (Wyoming), with fragmentary records from Middle J ...

''.

References

{{Taxonbar, from=Q30692638 Egg fossils Reptile trace fossils Tithonian life Late Jurassic crocodylomorphs of Europe Jurassic Portugal Fossils of Portugal Lourinhã Formation Fossil parataxa described in 2017