The evolution of mammalian olfaction is manifested in a remarkable diversity of gene repertoires, neuroanatomy, and skull morphology across living species. Olfactory receptor genes (ORG), which initiate the conversion of odorant molecules into odor perceptions and help an animal resolve the olfactory world, range in number from a mere handful to several thousand genes across species. Within the snout, each of these ORGs is exclusively expressed by a discrete population of olfactory sensory neurons (OSN), suggesting that newly evolved ORGs may be coupled with new OSN populations in the nasal epithelium. Because OSNs axon bundles leave high-fidelity perforations (foramina) in the bone as they traverse the cribriform plate (CP) to reach the brain, we predicted that taxa with larger ORG repertoires would have proportionately expanded footprints in the CP foramina. Previous work found a correlation between ORG number and absolute CP size that disappeared when body size effects were accounted for. Using updated, digital measurement data from high-resolution CT scans and reexamining the relationship between CP and body size, we report a striking linear correlation between relative CP area and number of functional ORGs across species from all mammalian superorders. This correlation suggests strong developmental links in the olfactory pathway between genes, neurons, and skull morphology. Furthermore, because ORG number is linked to olfactory discriminatory function, this correlation supports relative CP size as a viable metric for inferring olfactory capacity across modern and extinct species. By quantifying CP area from a fossil sabertooth cat (Smilodon fatalis) we predicted a likely ORG repertoire for this extinct felid.
Key resource table, Excel format
Key resource table for sample specimens, CT scanning machines and facilities, and digital imaging software.
S3_Supp Table_DJBird_PRSb_Excel.xlsx
Key resource table, .csv format
Key resource table for sample specimens, CT scanning machines and facilities, and digital imaging software.
S3_Supp Table_DJBird_PRSb_CSV.csv
Cribriform plate surface area data for individual specimens, Excel format
Identification, source, sex and morphological data for sample species. Abbreviations, AMNH: American Museum of Natural History. CMNH: Cleveland Museum of Natural History. DLC: Duke Lemur Center. DUPC: Duke University Primate Center. IZCAS: Institute of Zoology of the Chinese Academy of Sciences. LACM: Natural History Museum of Los Angeles County. LACMRLP: Rancho La Brea Tar Pits. MVZ: Museum of Vertebrate Zoology. SDSNH: San Diego Society of Natural History. UCLA: Dickey Collection at the University of California Los Angeles. UCLAEEB: UCLA Department of Ecology and Evolutionary Biology. USNM: National Museum of Natural History. UTO: University of Texas Austin. TMM: Texas Memorial Museum. *The presence of a cribriform plate in the ethmoid bone of the bottlenose dolphin (Tursiops truncatus) could not be established in this study.
S4_Supp Table_DJBird_PRSb_Excel.xlsx
Cribriform plate surface area data for individual specimens, .csv format
Identification, source, sex and morphological data for sample species. Abbreviations, AMNH: American Museum of Natural History. CMNH: Cleveland Museum of Natural History. DLC: Duke Lemur Center. DUPC: Duke University Primate Center. IZCAS: Institute of Zoology of the Chinese Academy of Sciences. LACM: Natural History Museum of Los Angeles County. LACMRLP: Rancho La Brea Tar Pits. MVZ: Museum of Vertebrate Zoology. SDSNH: San Diego Society of Natural History. UCLA: Dickey Collection at the University of California Los Angeles. UCLAEEB: UCLA Department of Ecology and Evolutionary Biology. USNM: National Museum of Natural History. UTO: University of Texas Austin. TMM: Texas Memorial Museum. *The presence of a cribriform plate in the ethmoid bone of the bottlenose dolphin (Tursiops truncatus) could not be established in this study.
S4_Supp Table_DJBird_PRSb_CSV.csv
Morphological and genomic data for sample species, Excel format
Abbreviations: CP, cribriform plate; ORG, olfactory receptor gene. Body mass estimates are species means. Where sexual dimorphism was present, we considered the sex of individuals when deriving the species body mass. Individual dog breed body size estimates were averaged to calculate the mean body mass of the dog (Canis familiaris). References for body mass and ORG data listed below the table. For cribriform plate surface area data of individual specimens, see table S5.
S8_Supp_Table_DJBird_PRSb_Excel.xlsx
Morphological and genomic data for sample species, .csv format
Abbreviations: CP, cribriform plate; ORG, olfactory receptor gene. Body mass estimates are species means. Where sexual dimorphism was present, we considered the sex of individuals when deriving the species body mass. Individual dog breed body size estimates were averaged to calculate the mean body mass of the dog (Canis familiaris). References for body mass and ORG data listed below the table. For cribriform plate surface area data of individual specimens, see table S5.
S8_Supp_Table_DJBird_PRSb_CSV.csv
Assembly statistics for genome assemblies from which olfactory receptor gene counts were extracted, Excel format
Abbreviations, BGI: Beijing Genomics Institute; BCM: Baylor College of Medicine; Broad: Broad Institute; ICGSC: International Cat Genome Sequencing Consortium; WU: Washington University. Sources of data: NCBI Assembly, University of California Santa Cruz Genome Browser, Genome Reference Consortium.
S9_Supp Table_DJBird_PRSb_Excel.xlsx
Assembly statistics for genome assemblies from which olfactory receptor gene counts were extracted; .csv format
Abbreviations, BGI: Beijing Genomics Institute; BCM: Baylor College of Medicine; Broad: Broad Institute; ICGSC: International Cat Genome Sequencing Consortium; WU: Washington University. Sources of data: NCBI Assembly, University of California Santa Cruz Genome Browser, Genome Reference Consortium.
S9_Supp Table_DJBird_PRSb_CSV.csv
Summary statistics, Excel format
Abbreviations: CP, Cribriform plate; RelCP, Relative cribriform plate size; ORG, Olfactory receptor genes; PGLS, Phylogenetic generalized least squares.
S10_Supp Table_DJBird_PRSb_Excel.xlsx
Summary statistics; .csv format
Abbreviations: CP, Cribriform plate; RelCP, Relative cribriform plate size; ORG, Olfactory receptor genes; PGLS, Phylogenetic generalized least squares.
S10_Supp Table_DJBird_PRSb_CSV.csv
Sources and morphological data for felid species; Excel format
Museums and collections are as follows: FMNH: Field Museum of Natural History; LACM: Museum of Natural History of Los Angeles County; LACMRLP: Rancho La Brea Tar Pits; MMNH: James Ford Bell Museum University of Minnesota, Minneapolis; UCLAEEB: University of California Los Angeles Department of Ecology and Evolutionary Biology. aEstimated body masses (in kg) are from [1] except for two species, Felis catus [9] and Smilodon fatalis [19] (see table S8 references).
S13_Supp Table_DJBird_PRSb_Excel.xlsx
Sources and morphological data for felid species; .csv format
Museums and collections are as follows: FMNH: Field Museum of Natural History; LACM: Museum of Natural History of Los Angeles County; LACMRLP: Rancho La Brea Tar Pits; MMNH: James Ford Bell Museum University of Minnesota, Minneapolis; UCLAEEB: University of California Los Angeles Department of Ecology and Evolutionary Biology. aEstimated body masses (in kg) are from [1] except for two species, Felis catus [9] and Smilodon fatalis [19] (see table S8 references).
S13_Supp Table_DJBird_PRSb_CSV.csv