(A) Top, UMAP plot showing clustering of murine cell types encompassing early mesodermal progenitors, FHF/second heart field (SHF) progenitors, LV/RV/OFT cardiomyocytes, and epicardial cells. Bottom-left, labeling of cell types by timepoint analyzed. Bottom-right, annotation by reference from which data was obtained. (B) UMAP embeddings of heart field development split by FHF and SHF lineages. (C) FHF and aSHF trajectory analysis and plotting of expression FHF (TBX5 and HCN4) and anterior SHF (TBX1 and FGF8) markers. (D) Analysis of FHF and aSHF marker expression during hiPSC cardiac differentiation. (E) Gene expression analysis of ventricular markers Iroquois transcription factor (IRX4) and myosin light chain-2 (MYL2) during hiPSC cardiac differentiation.