This work presents
a detailed structural and morphological analysis
of different dinosaur eggshells such as
Spheroolithus
(sample 1, 2), lambeosaurinae,
Prismatoolithus
,
and one unidentified ootaxon performed by high-resolution scanning
electron microscopy (HRSEM). These ancient eggshells of Late Cretaceous
dinosaurs were collected in the coastal area of El Rosario, Baja California
in Mexico. Additionally, a thorough study was performed on the elements
present in the samples by different techniques such as energy-dispersive
spectroscopy (EDS), X-ray fluorescence (XRF), and X-ray photoelectron
spectroscopy (XPS). The XPS technique was performed to make an accurate
identification of the compounds of two different types of eggshells
(
Spheroolithus
sample 1 and
Prismatoolithus
). This contribution compares the surface of five different dinosaur
eggshells of 74 Ma and their inner section to determine the morphology,
distribution of the chemical elements present, as well as their relationship.
The observed morphology of the ornithopod eggshells of the herbivorous
species shows that the mammillary cones are in the form of columns
with microaggregates and irregular pores. In contrast, in the theropod
eggshells, the mammillary cones are observed in different forms with
wider pores. Finally, the chemical components present in the structures
of each of the samples were estimated using the information obtained
from SEM-EDS, evidencing the presence of calcite, quartz, and albite
in each of the samples. The composition reveals that eggshells contain
Si, P, S, K, Ca, Mn, Fe, and Sr and trace elements such as Cr, Cu,
and Zn. The presence of heavy metals may be an indication that the
eggshells presented diagenetic alterations.