We find some "monsters" being studied by teratology, in the technical sense of congenital malformations, in the work by Thomas Bartholin (1616-1680) Acta medica & philosophica, held in Library of Pharmaceutical and Pharmacological Sciences of the University of Padova, the first edition of 1671 (digital copy).
Descriptions and illustrations of some foetal anomalies and one case of public scorn, of a monstrous child, conceived outside of marriage – the author points out – and displayed near the castle of Copenhagen to crowds of spectators of both sexes in exchange for alms for the mother (p. 53). There is also a child with elephant ears. The comparison to an elephant can also be seen in a "monstrum porcinum", which describes a mouth with two trunks. In addition to these cases from notoriety or from colleagues, Bartholin added some quirks of nature from his own garden including some resembling human organs, such as hunchback, in order to cure hunchback, according to the doctrine of signatures, of similia similibus curantur, a long-standing botanical tradition. The cases are reported as curiosities, without any attempt to explain, as simply jokes or errors of nature "Sicut... lusit Natura, vel aberravit" (thus Nature has had fun and created some aberrations) (p. 55).