Live birth in a 47‑million‑year‑old snake

CHULIVER, MARIANA; AGUSTÍN SCANFERLA; SMITH, KRISTER T.

NATURWISSENSCHAFTEN

SPRINGER

Lugar: Berlin; Año: 2022

0028-1042

Viviparity is a widespreadreproductive trait in snakes, although fossil evidence bearing on its evolutionis extremely sparse. Here, we report an exceptional specimen of the minutebooid snake Messelophis variatus recovered in the paleolake of the Messel Formation (early-middle Eocene,Germany). This gravid female contains at least two embryos located in theposterior third of the trunk region. The morphology, size, and degree ofossification of the cranial and postcranial remains indicate they correspondwith late embryos. This specimen documents the first occurrence of viviparityin a fossil snake and extends the temporal distribution of this reproductivestrategy in booid snakes by over 47 Ma. The evolution of viviparity insquamates has traditionally been associated with cold climates, but itspresence at the dawn of the evolution of booids during early Palaeogene thermalpeaks indicates that viviparity may have evolved under different selectivepressures in this clade.@font-face{font-family:"ＭＳ 明朝";mso-font-charset:78;mso-generic-font-family:auto;mso-font-pitch:variable;mso-font-signature:1 134676480 16 0 131072 0;}@font-face{font-family:"Cambria Math";panose-1:2 4 5 3 5 4 6 3 2 4;mso-font-charset:0;mso-generic-font-family:auto;mso-font-pitch:variable;mso-font-signature:3 0 0 0 1 0;}@font-face{font-family:Cambria;panose-1:2 4 5 3 5 4 6 3 2 4;mso-font-charset:0;mso-generic-font-family:auto;mso-font-pitch:variable;mso-font-signature:-536870145 1073743103 0 0 415 0;}p.MsoNormal, li.MsoNormal, div.MsoNormal{mso-style-unhide:no;mso-style-qformat:yes;mso-style-parent:"";margin:0cm;margin-bottom:.0001pt;mso-pagination:widow-orphan;font-size:11.0pt;font-family:Cambria;mso-ascii-font-family:Cambria;mso-ascii-theme-font:minor-latin;mso-fareast-font-family:Cambria;mso-fareast-theme-font:minor-latin;mso-hansi-font-family:Cambria;mso-hansi-theme-font:minor-latin;mso-bidi-font-family:"Times New Roman";mso-bidi-theme-font:minor-bidi;mso-ansi-language:ES-AR;mso-fareast-language:EN-US;}.MsoChpDefault{mso-style-type:export-only;mso-default-props:yes;font-family:Cambria;mso-ascii-font-family:Cambria;mso-ascii-theme-font:minor-latin;mso-fareast-font-family:"ＭＳ 明朝";mso-fareast-theme-font:minor-fareast;mso-hansi-font-family:Cambria;mso-hansi-theme-font:minor-latin;mso-bidi-font-family:"Times New Roman";mso-bidi-theme-font:minor-bidi;mso-fareast-language:JA;}div.WordSection1{page:WordSection1;}@font-face{font-family:"ＭＳ 明朝";mso-font-charset:78;mso-generic-font-family:auto;mso-font-pitch:variable;mso-font-signature:1 134676480 16 0 131072 0;}@font-face{font-family:"ＭＳ 明朝";mso-font-charset:78;mso-generic-font-family:auto;mso-font-pitch:variable;mso-font-signature:1 134676480 16 0 131072 0;}@font-face{font-family:Cambria;panose-1:2 4 5 3 5 4 6 3 2 4;mso-font-charset:0;mso-generic-font-family:auto;mso-font-pitch:variable;mso-font-signature:-536870145 1073743103 0 0 415 0;}p.MsoNormal, li.MsoNormal, div.MsoNormal{mso-style-unhide:no;mso-style-qformat:yes;mso-style-parent:"";margin:0cm;margin-bottom:.0001pt;mso-pagination:widow-orphan;font-size:11.0pt;font-family:Cambria;mso-ascii-font-family:Cambria;mso-ascii-theme-font:minor-latin;mso-fareast-font-family:Cambria;mso-fareast-theme-font:minor-latin;mso-hansi-font-family:Cambria;mso-hansi-theme-font:minor-latin;mso-bidi-font-family:"Times New Roman";mso-bidi-theme-font:minor-bidi;mso-ansi-language:ES-AR;mso-fareast-language:EN-US;}.MsoChpDefault{mso-style-type:export-only;mso-default-props:yes;font-family:Cambria;mso-ascii-font-family:Cambria;mso-ascii-theme-font:minor-latin;mso-fareast-font-family:"ＭＳ 明朝";mso-fareast-theme-font:minor-fareast;mso-hansi-font-family:Cambria;mso-hansi-theme-font:minor-latin;mso-bidi-font-family:"Times New Roman";mso-bidi-theme-font:minor-bidi;mso-fareast-language:JA;}div.WordSection1{page:WordSection1;}