[dinosaur] Echinerpeton (Carboniferous synapsid) redescribed as sail-backed ophiacodontid

Ben Creisler
[email protected]

A new paper:

Arjan Mann & Ryan S. Paterson (2019)
Cranial osteology and systematics of the enigmatic early 'sail-backed'
synapsid Echinerpeton intermedium Reisz, 1972, and a review of the earliest
'pelycosaurs'.
Journal of Systematic Palaeontology (advance online publication)
doi: https://urldefense.proofpoint.com/v2/url?u=https-3A__doi.org_10.1080_14772019.2019.1648323&d=DwIBaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=kE4HMJE84y2yjN8xpnwYDef15IAwDxnJr1C1vSLnnU0&s=hqB5EbvTUHBdZWUX9N2dHSt2LBXxMZmqD_gy4Tf1lnQ&e= 
https://urldefense.proofpoint.com/v2/url?u=https-3A__www.tandfonline.com_doi_full_10.1080_14772019.2019.1648323&d=DwIBaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=kE4HMJE84y2yjN8xpnwYDef15IAwDxnJr1C1vSLnnU0&s=v0XeGu3hbCWfTfW2FAduFxRbKxBsO8XRoqWA0f9K3-c&e= 


The early synapsid Echinerpeton intermedium from Florence, Nova Scotia, was
first described as a basal ophiacodontid 'pelycosaur,' displaying the
oldest record of hyper-elongated neural spines in an amniote. Since its
initial discovery, the systematic placement of Echinerpeton intermedium has
been less clear than that of its contemporary Archaeothyris florensis. The
difficulty in assigning the remains of Echinerpeton firmly to any broader
clade is largely the result of the incomplete nature of specimens,
particularly the lack of diagnostic cranial material. The most recent
large-scale phylogenies of basal synapsid interrelationships do not
consistently recover Echinerpeton in a stable position. Despite being one
of the earliest known synapsids, the volatility of the phylogenetic
position of Echinerpeton has resulted in its exclusion from many
large-scale phylogenetic analyses. Here, we describe the first new remains
of Echinerpeton since its initial discovery. RM 206866 includes substantial
new cranial material, and we provide the first comprehensive description of
its skull. Informative remains include a relatively complete
parabasisphenoid complex. Additionally, we revisit the phylogenetic
position of Echinerpeton using Bayesian inference and parsimony-based
methods, confirming the taxon as a member of Ophiacodontidae.

<https://urldefense.proofpoint.com/v2/url?u=http-3A__www.avg.com_email-2Dsignature-3Futm-5Fmedium-3Demail-26utm-5Fsource-3Dlink-26utm-5Fcampaign-3Dsig-2Demail-26utm-5Fcontent-3Dwebmail&d=DwIBaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=kE4HMJE84y2yjN8xpnwYDef15IAwDxnJr1C1vSLnnU0&s=IafDJoCJTP3HisRuxLO-ejmGuhujxp7WU9acOdYrLrQ&e= >
Virus-free.
www.avg.com
<https://urldefense.proofpoint.com/v2/url?u=http-3A__www.avg.com_email-2Dsignature-3Futm-5Fmedium-3Demail-26utm-5Fsource-3Dlink-26utm-5Fcampaign-3Dsig-2Demail-26utm-5Fcontent-3Dwebmail&d=DwIBaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=kE4HMJE84y2yjN8xpnwYDef15IAwDxnJr1C1vSLnnU0&s=IafDJoCJTP3HisRuxLO-ejmGuhujxp7WU9acOdYrLrQ&e= >
<#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2>