APPENDIX 2. — Linear regression equations used to estimate skull length for crocodylian specimens;total body length for vertebral regressions from Iijima & Kubo (2020). * measurement for final two rows, vertebral centrum length, is in mm. Abbreviations: KNM, National Museums of Kenya; N, number of specimens; NHML, Natural History Museum (London); SL, skull length; TBI, Turkana Basin Insitute; TL, total body length.

Taxon	Measurement, x (cm*)	Regression to SL (in cm) Regression and TL (in mm) trained on N =		Sources for regression data
Euthecodon	Mandible length	SL = 0.8754*x + 1.2113	4	KNM-ER 757, KNM-KP 18330, KNM-ER 8260, KNM-LT 26306
	Mandible length to posterior of dentary articulation	SL = 0.8754*x + 1.2113	5	NMK-ER 757, KNM-KP 18330, KNM-ER 8260, KNM-LT 26306, KNM-KP 66227
	Average tooth spacing (excluding two anteriormost tooth sockets)	SL = 19.966*x + 30.446	4	KNM-ER 757, KNM-LT 26306, KNM-ER 8260, KNM-ER 18330
cf. Mecistops	Narrowest width of premaxilla Length of mandibular symphysis	SL = 9.97*x SL = 3.8706*x	1 1	NME L 398 2508A NME L 398 2508A
Crocodylus	Mandible length Mandible length to posterior of dentary articulation	SL = 0.6829*x +6.4381 SL = 0.8206*x + 4.5791	23 19	NHML collections NHML collections
	Length of mandibular symphysis Height of dentary at posterior end of mandibular symphysis	SL = 3.1846*x + 17.789 SL = 13.158*x	20 2	NHML collections NME AL 126-11, L.449-4 (Hadar, Shungura Crocodylus)
	Length between centers of d9-d12 alveoli	SL = 5.1384*x + 8.318	18	NHML collections
	Femur circumference D3-D10 vertebral centrum length C8-D2 vertebral centrum length	SL = 4.8793*x + 1.2857 log(TL) = 1.906 + 0.993*log(x) log(TL) = 2.015 + 0.956*log(x)	4 5 2	NHML collections Iijima & Kubo 2020 Iijima & Kubo 2020