{"id":"https://openalex.org/W2010786941","doi":"https://doi.org/10.1073/pnas.86.13.4992","title":"Modern mammal origins: evolutionary grades in the Early Cretaceous of North America.","display_name":"Modern mammal origins: evolutionary grades in the Early Cretaceous of North America.","publication_year":1989,"publication_date":"1989-07-01","ids":{"openalex":"https://openalex.org/W2010786941","doi":"https://doi.org/10.1073/pnas.86.13.4992","mag":"2010786941","pmid":"https://pubmed.ncbi.nlm.nih.gov/2740336","pmcid":"https://www.ncbi.nlm.nih.gov/pmc/articles/297542"},"language":"en","primary_location":{"id":"doi:10.1073/pnas.86.13.4992","doi":"https://doi.org/10.1073/pnas.86.13.4992","is_oa":false,"landing_page_url":"https://doi.org/10.1073/pnas.86.13.4992","pdf_url":null,"source":{"id":"https://openalex.org/S125754415","display_name":"Proceedings of the National Academy of Sciences","issn_l":"0027-8424","issn":["0027-8424","1091-6490"],"is_oa":false,"is_in_doaj":false,"is_core":true,"listed_in":["anvur-class-a","anvur-scientific","cwts-core","dongbi-a","doyens","erih-plus","jufo-3","ki-jl-3","medline","norway-2","poland-200","russia-white-list-1","vabb-shw"],"host_organization":"https://openalex.org/P4310320052","host_organization_name":"National Academy of Sciences","host_organization_lineage":["https://openalex.org/P4310320052"],"host_organization_lineage_names":["National Academy of Sciences"],"type":"journal"},"license":null,"license_id":null,"version":"publishedVersion","is_accepted":true,"is_published":true,"raw_source_name":"Proceedings of the National Academy of Sciences","raw_type":"journal-article"},"volume":null,"type":"article","is_traditional":true,"indexed_in":["crossref","pubmed"],"open_access":{"is_oa":true,"oa_status":"green","oa_url":"https://www.ncbi.nlm.nih.gov/pmc/articles/297542","any_repository_has_fulltext":true},"authorships":[{"author_position":"first","author":{"id":"https://openalex.org/A5083049438","display_name":"Louis L. Jacobs","orcid":"https://orcid.org/0000-0002-7735-3678","observed_orcids":["https://orcid.org/0000-0002-7735-3678"]},"institutions":[{"id":"https://openalex.org/I178169726","display_name":"Southern Methodist University","ror":"https://ror.org/042tdr378","country_code":"US","type":"education","lineage":["https://openalex.org/I178169726"]}],"countries":["US"],"is_corresponding":false,"raw_author_name":"L L Jacobs","raw_affiliation_strings":["Shuler Museum of Paleontology, Southern Methodist University, Dallas, TX 75275"],"raw_orcid":null,"affiliations":[{"raw_affiliation_string":"Shuler Museum of Paleontology, Southern Methodist University, Dallas, TX 75275","institution_ids":["https://openalex.org/I178169726"]}]},{"author_position":"middle","author":{"id":"https://openalex.org/A5076173216","display_name":"David Alan Winkler","orcid":"https://orcid.org/0000-0002-7301-6076","observed_orcids":["https://orcid.org/0000-0002-7301-6076","https://orcid.org/0000-0003-2423-674X"]},"institutions":[{"id":"https://openalex.org/I178169726","display_name":"Southern Methodist University","ror":"https://ror.org/042tdr378","country_code":"US","type":"education","lineage":["https://openalex.org/I178169726"]},{"id":"https://openalex.org/I75063564","display_name":"Tarleton State University","ror":"https://ror.org/0263v9e25","country_code":"US","type":"education","lineage":["https://openalex.org/I75063564"]}],"countries":["US"],"is_corresponding":false,"raw_author_name":"D A Winkler","raw_affiliation_strings":["Shuler Museum of Paleontology, Southern Methodist University, Dallas, TX 75275","Shuler Museum of Paleontology, Southern Methodist University, Dallas, TX 75275; and tDepartment of Physical Sciences,","Tarleton State University, Stephenville, TX 76402"],"raw_orcid":null,"affiliations":[{"raw_affiliation_string":"Shuler Museum of Paleontology, Southern Methodist University, Dallas, TX 75275","institution_ids":["https://openalex.org/I178169726"]},{"raw_affiliation_string":"Shuler Museum of Paleontology, Southern Methodist University, Dallas, TX 75275; and tDepartment of Physical Sciences,","institution_ids":["https://openalex.org/I178169726"]},{"raw_affiliation_string":"Tarleton State University, Stephenville, TX 76402","institution_ids":["https://openalex.org/I75063564"]}]},{"author_position":"last","author":{"id":"https://openalex.org/A5013188668","display_name":"Phillip A. Murry","orcid":null,"observed_orcids":[]},"institutions":[{"id":"https://openalex.org/I178169726","display_name":"Southern Methodist University","ror":"https://ror.org/042tdr378","country_code":"US","type":"education","lineage":["https://openalex.org/I178169726"]}],"countries":["US"],"is_corresponding":false,"raw_author_name":"P A Murry","raw_affiliation_strings":["Shuler Museum of Paleontology, Southern Methodist University, Dallas, TX 75275"],"raw_orcid":null,"affiliations":[{"raw_affiliation_string":"Shuler Museum of Paleontology, Southern Methodist University, Dallas, TX 75275","institution_ids":["https://openalex.org/I178169726"]}]}],"institutions":[],"countries_distinct_count":1,"institutions_distinct_count":2,"corresponding_author_ids":[],"corresponding_institution_ids":[],"apc_list":null,"apc_paid":null,"fwci":0.4883,"has_fulltext":false,"cited_by_count":33,"citation_normalized_percentile":{"value":0.60217697,"is_in_top_1_percent":false,"is_in_top_10_percent":false},"cited_by_percentile_year":{"min":88,"max":97},"biblio":{"volume":"86","issue":"13","first_page":"4992","last_page":"4995"},"is_retracted":false,"is_paratext":false,"is_xpac":false,"primary_topic":{"id":"https://openalex.org/T11354","display_name":"Evolution and Paleontology Studies","score":0.9951000213623047,"subfield":{"id":"https://openalex.org/subfields/1911","display_name":"Paleontology"},"field":{"id":"https://openalex.org/fields/19","display_name":"Earth and Planetary Sciences"},"domain":{"id":"https://openalex.org/domains/3","display_name":"Physical Sciences"}},"topics":[{"id":"https://openalex.org/T11354","display_name":"Evolution and Paleontology Studies","score":0.9951000213623047,"subfield":{"id":"https://openalex.org/subfields/1911","display_name":"Paleontology"},"field":{"id":"https://openalex.org/fields/19","display_name":"Earth and Planetary Sciences"},"domain":{"id":"https://openalex.org/domains/3","display_name":"Physical Sciences"}},{"id":"https://openalex.org/T10955","display_name":"Paleontology and Evolutionary Biology","score":0.004399999976158142,"subfield":{"id":"https://openalex.org/subfields/1911","display_name":"Paleontology"},"field":{"id":"https://openalex.org/fields/19","display_name":"Earth and Planetary Sciences"},"domain":{"id":"https://openalex.org/domains/3","display_name":"Physical Sciences"}},{"id":"https://openalex.org/T10421","display_name":"Pleistocene-Era Hominins and Archaeology","score":9.999999747378752e-05,"subfield":{"id":"https://openalex.org/subfields/3314","display_name":"Anthropology"},"field":{"id":"https://openalex.org/fields/33","display_name":"Social Sciences"},"domain":{"id":"https://openalex.org/domains/2","display_name":"Social Sciences"}}],"keywords":[{"id":"https://openalex.org/keywords/mammalian-origins","display_name":"mammalian origins","score":0.8500000238418579},{"id":"https://openalex.org/keywords/early-cretaceous","display_name":"Lower Cretaceous","score":0.8569999933242798},{"id":"https://openalex.org/keywords/tribosphenic-molar","display_name":"tribosphenic molar","score":0.8939999938011169},{"id":"https://openalex.org/keywords/tooth-wear-facets","display_name":"tooth wear facets","score":0.7049999833106995},{"id":"https://openalex.org/keywords/protocone","display_name":"protocone","score":0.6589999794960022},{"id":"https://openalex.org/keywords/marsupials","display_name":"marsupials","score":0.7129999995231628},{"id":"https://openalex.org/keywords/placentals","display_name":"placentals","score":0.9330000281333923},{"id":"https://openalex.org/keywords/molar-morphology","display_name":"molar morphology","score":0.6200000047683716},{"id":"https://openalex.org/keywords/mesozoic-mammals","display_name":"Mesozoic mammals","score":0.6690000295639038},{"id":"https://openalex.org/keywords/dental-evolution","display_name":"dental evolution","score":0.4830000102519989}],"concepts":[{"id":"https://openalex.org/C2780247652","wikidata":"https://www.wikidata.org/wiki/Q18534251","display_name":"Cheek teeth","level":2,"score":0.7604855298995972},{"id":"https://openalex.org/C139690037","wikidata":"https://www.wikidata.org/wiki/Q785301","display_name":"Evolution of mammals","level":3,"score":0.7459337115287781},{"id":"https://openalex.org/C2778234026","wikidata":"https://www.wikidata.org/wiki/Q7377","display_name":"Mammal","level":2,"score":0.7002928853034973},{"id":"https://openalex.org/C12294951","wikidata":"https://www.wikidata.org/wiki/Q44626","display_name":"Cretaceous","level":2,"score":0.6845085024833679},{"id":"https://openalex.org/C202271784","wikidata":"https://www.wikidata.org/wiki/Q189218","display_name":"Molar","level":2,"score":0.6724293828010559},{"id":"https://openalex.org/C86803240","wikidata":"https://www.wikidata.org/wiki/Q420","display_name":"Biology","level":0,"score":0.6500748991966248},{"id":"https://openalex.org/C188126409","wikidata":"https://www.wikidata.org/wiki/Q641973","display_name":"Dentition","level":2,"score":0.6189658045768738},{"id":"https://openalex.org/C178300618","wikidata":"https://www.wikidata.org/wiki/Q1898509","display_name":"Extant taxon","level":2,"score":0.6121771931648254},{"id":"https://openalex.org/C499950583","wikidata":"https://www.wikidata.org/wiki/Q183252","display_name":"Morphology (biology)","level":2,"score":0.5351539254188538},{"id":"https://openalex.org/C2776110070","wikidata":"https://www.wikidata.org/wiki/Q2455930","display_name":"Fossil Record","level":2,"score":0.5098954439163208},{"id":"https://openalex.org/C202783661","wikidata":"https://www.wikidata.org/wiki/Q83222","display_name":"Mesozoic","level":3,"score":0.48869040608406067},{"id":"https://openalex.org/C78458016","wikidata":"https://www.wikidata.org/wiki/Q840400","display_name":"Evolutionary biology","level":1,"score":0.4858393371105194},{"id":"https://openalex.org/C151730666","wikidata":"https://www.wikidata.org/wiki/Q7205","display_name":"Paleontology","level":1,"score":0.4744097888469696},{"id":"https://openalex.org/C62142553","wikidata":"https://www.wikidata.org/wiki/Q200312","display_name":"Convergent evolution","level":4,"score":0.46753618121147156},{"id":"https://openalex.org/C2778400075","wikidata":"https://www.wikidata.org/wiki/Q655275","display_name":"Cusp (singularity)","level":2,"score":0.4663139283657074},{"id":"https://openalex.org/C2988562018","wikidata":"https://www.wikidata.org/wiki/Q1063","display_name":"Biological evolution","level":2,"score":0.4294969141483307},{"id":"https://openalex.org/C90132467","wikidata":"https://www.wikidata.org/wiki/Q171184","display_name":"Phylogenetics","level":3,"score":0.30600467324256897},{"id":"https://openalex.org/C55493867","wikidata":"https://www.wikidata.org/wiki/Q7094","display_name":"Biochemistry","level":1,"score":0.0},{"id":"https://openalex.org/C104317684","wikidata":"https://www.wikidata.org/wiki/Q7187","display_name":"Gene","level":2,"score":0.0},{"id":"https://openalex.org/C109007969","wikidata":"https://www.wikidata.org/wiki/Q749565","display_name":"Structural basin","level":2,"score":0.0},{"id":"https://openalex.org/C33923547","wikidata":"https://www.wikidata.org/wiki/Q395","display_name":"Mathematics","level":0,"score":0.0},{"id":"https://openalex.org/C2524010","wikidata":"https://www.wikidata.org/wiki/Q8087","display_name":"Geometry","level":1,"score":0.0},{"id":"https://openalex.org/C54355233","wikidata":"https://www.wikidata.org/wiki/Q7162","display_name":"Genetics","level":1,"score":0.0}],"mesh":[{"descriptor_ui":"D000818","descriptor_name":"Animals","qualifier_ui":null,"qualifier_name":null,"is_major_topic":false},{"descriptor_ui":"D005075","descriptor_name":"Biological Evolution","qualifier_ui":null,"qualifier_name":null,"is_major_topic":true},{"descriptor_ui":"D005580","descriptor_name":"Fossils","qualifier_ui":null,"qualifier_name":null,"is_major_topic":true},{"descriptor_ui":"D008322","descriptor_name":"Mammals","qualifier_ui":"Q000033","qualifier_name":"anatomy & histology","is_major_topic":true},{"descriptor_ui":"D008394","descriptor_name":"Marsupialia","qualifier_ui":"Q000033","qualifier_name":"anatomy & histology","is_major_topic":false},{"descriptor_ui":"D010161","descriptor_name":"Paleodontology","qualifier_ui":null,"qualifier_name":null,"is_major_topic":false},{"descriptor_ui":"D010163","descriptor_name":"Paleontology","qualifier_ui":null,"qualifier_name":null,"is_major_topic":true},{"descriptor_ui":"D013781","descriptor_name":"Texas","qualifier_ui":null,"qualifier_name":null,"is_major_topic":false},{"descriptor_ui":"D014070","descriptor_name":"Tooth","qualifier_ui":"Q000033","qualifier_name":"anatomy & histology","is_major_topic":true}],"locations_count":3,"locations":[{"id":"doi:10.1073/pnas.86.13.4992","doi":"https://doi.org/10.1073/pnas.86.13.4992","is_oa":false,"landing_page_url":"https://doi.org/10.1073/pnas.86.13.4992","pdf_url":null,"source":{"id":"https://openalex.org/S125754415","display_name":"Proceedings of the National Academy of Sciences","issn_l":"0027-8424","issn":["0027-8424","1091-6490"],"is_oa":false,"is_in_doaj":false,"is_core":true,"listed_in":["anvur-class-a","anvur-scientific","cwts-core","dongbi-a","doyens","erih-plus","jufo-3","ki-jl-3","medline","norway-2","poland-200","russia-white-list-1","vabb-shw"],"host_organization":"https://openalex.org/P4310320052","host_organization_name":"National Academy of Sciences","host_organization_lineage":["https://openalex.org/P4310320052"],"host_organization_lineage_names":["National Academy of Sciences"],"type":"journal"},"license":null,"license_id":null,"version":"publishedVersion","is_accepted":true,"is_published":true,"raw_source_name":"Proceedings of the National Academy of Sciences","raw_type":"journal-article"},{"id":"pmh:oai:pubmedcentral.nih.gov:297542","doi":null,"is_oa":true,"landing_page_url":"https://www.ncbi.nlm.nih.gov/pmc/articles/297542","pdf_url":null,"source":{"id":"https://openalex.org/S2764455111","display_name":"PubMed Central","issn_l":null,"issn":null,"is_oa":true,"is_in_doaj":false,"is_core":false,"listed_in":[],"host_organization":"https://openalex.org/I1299303238","host_organization_name":"National Institutes of Health","host_organization_lineage":["https://openalex.org/I1299303238"],"host_organization_lineage_names":[],"type":"repository"},"license":null,"license_id":null,"version":"publishedVersion","is_accepted":true,"is_published":true,"raw_source_name":"Proc Natl Acad Sci U S A","raw_type":"Text"},{"id":"pmid:2740336","doi":null,"is_oa":false,"landing_page_url":"https://pubmed.ncbi.nlm.nih.gov/2740336","pdf_url":null,"source":{"id":"https://openalex.org/S4306525036","display_name":"PubMed","issn_l":null,"issn":null,"is_oa":false,"is_in_doaj":false,"is_core":false,"listed_in":[],"host_organization":"https://openalex.org/I1299303238","host_organization_name":"National Institutes of Health","host_organization_lineage":["https://openalex.org/I1299303238"],"host_organization_lineage_names":[],"type":"repository"},"license":null,"license_id":null,"version":"publishedVersion","is_accepted":true,"is_published":true,"raw_source_name":"Proceedings of the National Academy of Sciences of the United States of America","raw_type":"Journal Article"}],"best_oa_location":{"id":"pmh:oai:pubmedcentral.nih.gov:297542","doi":null,"is_oa":true,"landing_page_url":"https://www.ncbi.nlm.nih.gov/pmc/articles/297542","pdf_url":null,"source":{"id":"https://openalex.org/S2764455111","display_name":"PubMed Central","issn_l":null,"issn":null,"is_oa":true,"is_in_doaj":false,"is_core":false,"listed_in":[],"host_organization":"https://openalex.org/I1299303238","host_organization_name":"National Institutes of Health","host_organization_lineage":["https://openalex.org/I1299303238"],"host_organization_lineage_names":[],"type":"repository"},"license":null,"license_id":null,"version":"publishedVersion","is_accepted":true,"is_published":true,"raw_source_name":"Proc Natl Acad Sci U S A","raw_type":"Text"},"sustainable_development_goals":[],"study_designs":[],"awards":[],"funders":[{"id":"https://openalex.org/F4320306076","display_name":"National Science Foundation","ror":"https://ror.org/021nxhr62"},{"id":"https://openalex.org/F4320309024","display_name":"National Geographic Society","ror":"https://ror.org/04bqh5m06"},{"id":"https://openalex.org/F4320318036","display_name":"Southern Methodist University","ror":"https://ror.org/042tdr378"}],"has_content":{"grobid_xml":false,"pdf":false},"content_urls":null,"referenced_works_count":5,"referenced_works":["https://openalex.org/W598556749","https://openalex.org/W1539913220","https://openalex.org/W1947910026","https://openalex.org/W2021455095","https://openalex.org/W2025120504"],"related_works":["https://openalex.org/W2015390002","https://openalex.org/W1993086068","https://openalex.org/W2055531170","https://openalex.org/W2034000671","https://openalex.org/W1599379062","https://openalex.org/W2063365464","https://openalex.org/W7163186487","https://openalex.org/W1983805328","https://openalex.org/W2293803889","https://openalex.org/W6949583300"],"abstract_inverted_index":{"Major":[0],"groups":[1,90],"of":[2,38,49,52,75,91,104,113,116,138,160,171,178,182],"modern":[3,30],"mammals":[4,31],"have":[5],"their":[6],"origins":[7],"in":[8,64,68,119,144],"the":[9,13,50,69,73,83,96,114,135,139,149,161,179],"Mesozoic":[10],"Era,":[11],"yet":[12],"mammalian":[14,65,172],"fossil":[15],"record":[16],"is":[17,127,141],"generally":[18],"poor":[19],"for":[20],"that":[21,27,55],"time":[22],"interval.":[23],"Fundamental":[24],"morphological":[25,165],"changes":[26],"led":[28],"to":[29,156],"are":[32],"often":[33],"represented":[34],"by":[35,59],"small":[36],"samples":[37],"isolated":[39],"teeth.":[40],"Fortunately,":[41],"functional":[42],"wear":[43],"facets":[44],"on":[45,110],"teeth":[46,54],"allow":[47],"prediction":[48],"morphology":[51,115],"occluding":[53],"may":[56],"be":[57],"unrepresented":[58],"fossils.":[60],"A":[61,93],"major":[62],"step":[63],"evolution":[66,74,173],"occurred":[67],"Early":[70,97],"Cretaceous":[71,98],"with":[72],"tribosphenic":[76,121],"molars,":[77],"which":[78],"characterize":[79],"marsupials":[80],"and":[81,87,174],"placentals,":[82],"two":[84],"most":[85],"abundant":[86],"diverse":[88],"extant":[89],"mammals.":[92],"tooth":[94,140],"from":[95],"(110":[99],"million":[100],"years":[101],"before":[102],"present)":[103],"Texas":[105],"tests":[106],"previous":[107,176],"predictions":[108],"(based":[109],"lower":[111],"molars)":[112],"upper":[117],"molars":[118],"early":[120],"dentitions.":[122],"The":[123,151],"lingual":[124],"cusp":[125],"(protocone)":[126],"primitively":[128],"without":[129],"shear":[130],"facets,":[131],"as":[132],"expected,":[133],"but":[134],"cheek":[136],"side":[137],"derived":[142],"(advanced)":[143],"having":[145],"distinctive":[146],"cusps":[147],"along":[148],"margin.":[150],"tooth,":[152],"although":[153],"distressingly":[154],"inadequate":[155],"define":[157],"many":[158],"features":[159],"organism,":[162],"demonstrates":[163],"unexpected":[164],"diversity":[166],"at":[167],"a":[168],"strategic":[169],"stage":[170],"falsifies":[175],"claims":[177],"earliest":[180],"occurrence":[181],"true":[183],"marsupials.":[184]},"counts_by_year":[{"year":2026,"cited_by_count":2},{"year":2022,"cited_by_count":1},{"year":2015,"cited_by_count":3},{"year":2012,"cited_by_count":1}],"updated_date":"2026-11-04T10:54:05.112534","created_date":"2016-06-24T00:00:00"}