The AKC standard also emphasizes a square dog: «Length, measured from the point of shoulder to point of ischium (tuberosity), practically the same as height.» (oldenglishsheepdogclubofamerica.org)
The 4.4 - million - year - old hominin known as Ardi (Ardipithecus ramidus) had pelvic bones oriented in such a way that its hip flexors could extend almost as much those of modern humans, despite having a long, apelike ischium. (sciencemag.org)
In this position the ischiocrurale muscle (the muscle group stretching from the backside of the thighs by the ischium to right under the knee joint), are stretched. (babywearingschool.com)