The Cedar Mountain Formation in Utah is abode to the Mussentuchit Member , a web site where the first fossil shell from the Cenomanian years ( ~100 million yr ago ) was described 50 years ago . The diversity offossil testis – cognize by the fun Book " oodiversity " – had been limited to just one mentally ill taxonomic group , Macroelongatoolithus carlylei . Now , a team of scientist has shake up the fossil bollock disc as it discovered a remarkable multifariousness of eggshells while prospecting in Utah .
After half a century of not much to shout about in the way of dodo eggs from the part , an international team of scientist go down out to find the lawful diversity of ballock to be found here . Shell fragments might not be so electrifying as a jumbo skull , but they are a expectant fashion of searching for indicators of biodiversity when the body fogy record is limited .
arm with over 4,000 fossil eggshell fragment from 20 placement within the Mussentuchit Member , the squad categorized the shard free-base on their external aerofoil features . They also conduct detailed microscopical analyses to assess shell thickness , internal microstructure , and pore systems . They used scan electron microscopy to blemish the fine details , but telling one species ' shell from another is n’t easy .
A graphical abstract of the study.Image credit: Ryan Tucker and Josh Hedge,CC-BY 4.0
" It is sly based on eggshells alone , " saidDr Josh Hedge , Visiting Assistant Professor of Biology at Lake Forest College , to IFLScience . " We are reliant on happen associated bones , plate , whole testis , nests , and embryos together to make the best estimate . Where we do n’t have all of these , we can have-to doe with firearm of shell to like type see elsewhere . At this point , we have a pretty good thought of which types of shell were used by declamatory dinosaur grouping , but it is certainly very difficult to arrogate them to individual coinage . "
Their efforts were rewarded with the discovery of newly identified eggshell types , confirming that at least six different fossil testis species ( fuck as ootaxa ) lived here around 100 million age ago . Ootaxa sort out nut base on their morphological characteristics rather than directly linking them to specific species .
Three of the identified ootaxa belong to Elongatoolithidae oogenera ( Macroelongatoolithus , Undulatoolithus , Continuoolithus ) , a grouping associated with oviraptorosaurs . Two others belonged toSpheroolithus , which are eggs laid by ornithopod , and the final eggshell eccentric was identified asMycomorphoolithus kohringi , a crocodylomorph reptile .
Features ofUndulatoolithusfragment NCSM 33729. A) Surface view of NCSM 33729. The red line indicates where a thin section was made (dashed where not seen in the radial thin sections). B) NCSM 33729 in radial thin section. Tailed scale bar marks very high, undulating ornamentation. The gradational ML/CL boundary is marked with solid black lines; accretion lines in CL are shown with dashed black lines; arrows and black fill show infilled pores. C) Radial thin section under crossed polars. Scale bars equal 10 mm.Image credit: Hedge et al., 2025, PLOS One,CC-BY 4.0
The bailiwick marks the first time several of these ootaxa have been identify in North America , includingMycomorphoolithus , which was antecedently only known from Europe . It ’s also the early evidence of multiple oviraptorosaurs live on in close range in North America , paint a picture that these dinosaur were more diverse and widespread than antecedently believed .
" The most interesting thing about this for me is the multiple types of elongatoolithid eggshell , which correspond to multiple types of oviraptorosaur dinosaur , " tally Hedge . " I think historically we have been guilty of thinking there is one kind of each dinosaur in a give ecosystem , but we are finding more and more that multiple species of each group are in all likelihood co - existing . Our analysis suggests that we have at least two or three oviraptorosaurs of different sizes lay eggs in this ecosystem at around the same prison term . "
The subject brook the estimate that Cretaceous North American ecosystems were more complex than previously realized , with a peachy variety of cuddle behaviors and coinage interactions . This could have implications for understanding dinosaur migration , evolutionary family relationship , and ecosystem stability during the Cenomanian eld .
Seems prospecting for fossil eggs really is all it ’s crack up to be .
The bailiwick is published in the journalPLOS ONE .
